Added Wire_slave.h (no actual i2c slave implementation yet)

STM32F1/libraries/Wire/Wire_slave.h

@@ -0,0 +1 @@
+#error "Something is trying to include Wire.h when Wire_Slave.h is already included, they are mutually exclusive"

STM32F1/libraries/Wire/library.properties

@@ -0,0 +1,10 @@
+name=Wire
+version=1.0
+author=Arduino
+maintainer=Arduino <info@arduino.cc>
+sentence=Allows the communication between devices or sensors connected via Two Wire Interface Bus.
+paragraph=
+category=Communication
+url=http://www.arduino.cc/en/Reference/Wire
+architectures=STM32F1
+include=Wire.h

STM32F1/libraries/WireSlave/examples/SFRRanger_reader/SFRRanger_reader.ino

@@ -0,0 +1,87 @@
+// I2C SRF10 or SRF08 Devantech Ultrasonic Ranger Finder
+// by Nicholas Zambetti <http://www.zambetti.com>
+// and James Tichenor <http://www.jamestichenor.net>
+
+// Demonstrates use of the Wire library reading data from the
+// Devantech Utrasonic Rangers SFR08 and SFR10
+
+// Created 29 April 2006
+
+// This example code is in the public domain.
+
+
+#include <Wire_slave.h>
+
+void setup()
+{
+  Wire.begin();                // join i2c bus (address optional for master)
+  Serial.begin(9600);          // start serial communication at 9600bps
+}
+
+int reading = 0;
+
+void loop()
+{
+  // step 1: instruct sensor to read echoes
+  Wire.beginTransmission(112); // transmit to device #112 (0x70)
+                               // the address specified in the datasheet is 224 (0xE0)
+                               // but i2c adressing uses the high 7 bits so it's 112
+  Wire.write(byte(0x00));      // sets register pointer to the command register (0x00)
+  Wire.write(byte(0x50));      // command sensor to measure in "inches" (0x50)
+                               // use 0x51 for centimeters
+                               // use 0x52 for ping microseconds
+  Wire.endTransmission();      // stop transmitting
+
+  // step 2: wait for readings to happen
+  delay(70);                   // datasheet suggests at least 65 milliseconds
+
+  // step 3: instruct sensor to return a particular echo reading
+  Wire.beginTransmission(112); // transmit to device #112
+  Wire.write(byte(0x02));      // sets register pointer to echo #1 register (0x02)
+  Wire.endTransmission();      // stop transmitting
+
+  // step 4: request reading from sensor
+  Wire.requestFrom(112, 2);    // request 2 bytes from slave device #112
+
+  // step 5: receive reading from sensor
+  if(2 <= Wire.available())    // if two bytes were received
+  {
+    reading = Wire.read();  // receive high byte (overwrites previous reading)
+    reading = reading << 8;    // shift high byte to be high 8 bits
+    reading |= Wire.read(); // receive low byte as lower 8 bits
+    Serial.println(reading);   // print the reading
+  }
+
+  delay(250);                  // wait a bit since people have to read the output :)
+}
+
+
+/*
+
+// The following code changes the address of a Devantech Ultrasonic Range Finder (SRF10 or SRF08)
+// usage: changeAddress(0x70, 0xE6);
+
+void changeAddress(byte oldAddress, byte newAddress)
+{
+  Wire.beginTransmission(oldAddress);
+  Wire.write(byte(0x00));
+  Wire.write(byte(0xA0));
+  Wire.endTransmission();
+
+  Wire.beginTransmission(oldAddress);
+  Wire.write(byte(0x00));
+  Wire.write(byte(0xAA));
+  Wire.endTransmission();
+
+  Wire.beginTransmission(oldAddress);
+  Wire.write(byte(0x00));
+  Wire.write(byte(0xA5));
+  Wire.endTransmission();
+
+  Wire.beginTransmission(oldAddress);
+  Wire.write(byte(0x00));
+  Wire.write(newAddress);
+  Wire.endTransmission();
+}
+
+*/

STM32F1/libraries/WireSlave/examples/digital_potentiometer/digital_potentiometer.ino

@@ -0,0 +1,38 @@
+// I2C Digital Potentiometer
+// by Nicholas Zambetti <http://www.zambetti.com>
+// and Shawn Bonkowski <http://people.interaction-ivrea.it/s.bonkowski/>
+
+// Demonstrates use of the Wire library
+// Controls AD5171 digital potentiometer via I2C/TWI
+
+// Created 31 March 2006
+
+// This example code is in the public domain.
+
+// This example code is in the public domain.
+
+
+#include <Wire_slave.h>
+
+void setup()
+{
+  Wire.begin(); // join i2c bus (address optional for master)
+}
+
+byte val = 0;
+
+void loop()
+{
+  Wire.beginTransmission(44); // transmit to device #44 (0x2c)
+                              // device address is specified in datasheet
+  Wire.write(byte(0x00));            // sends instruction byte
+  Wire.write(val);             // sends potentiometer value byte
+  Wire.endTransmission();     // stop transmitting
+
+  val++;        // increment value
+  if(val == 64) // if reached 64th position (max)
+  {
+    val = 0;    // start over from lowest value
+  }
+  delay(500);
+}

STM32F1/libraries/WireSlave/examples/i2c_libmaple_slave/i2c_libmaple_slave.ino

@@ -0,0 +1,122 @@
+/*
+* i2c_slave example.cpp
+*
+*  You can use this sketch in combination with master_writer.pde
+*
+*  Created on: 4 Sep 2012
+*      Author: Barry Carter <barry.carter@gmail.com>
+*/
+#include <Arduino.h>
+#include <libmaple/i2c.h>
+
+#define USE_BUFFERED_EXAMPLE 1
+
+i2c_msg msg;
+uint8 buffer[255];
+char* const bufferAsChar = (char*)buffer; // ready type casted alias
+
+volatile bool newMessage = false;
+
+void funcrx(i2c_msg *msg __attribute__((unused))){
+  // Received length will be in msg->length
+  newMessage = true;
+}
+
+#if USE_BUFFERED_EXAMPLE == 1
+/* We ARE using a buffer to transmit the data out.
+* Make sure you fill the buffer with the data AND you set the length correctly
+*/
+void functx(i2c_msg *msg){
+  // Cheeky. We are using the received byte of the data which is currently in
+  // byte 0 to echo it back to the master device
+  //msg->data[0] = 0x01;    // We are re-using the rx buffer here to echo the request back
+  msg->data[1] = 0x02;
+  msg->data[2] = 0x03;
+  msg->data[3] = 0x04;
+  msg->data[4] = 0x05;
+  msg->length = 5;
+}
+
+#else
+
+/* We are NOT using the buffered data transmission
+* We will get this callback for each outgoing packet. Make sure to call i2c_write
+* Strickly speaking, we should be sending a NACk on the last byte we want to send
+* but for this test example I am going to assume the master will NACK it when it
+* wants to stop.
+*/
+void functx(i2c_msg *msg){
+  i2c_write(I2C1, msg->data[0]);
+}
+
+#endif
+
+// #define Serial Serial1
+
+void setup() {
+  Serial.begin(115200);
+  while(!Serial)
+    ;
+  Serial.println("I2C Slave example");
+
+  // attach the buffer
+  msg.data = buffer;
+
+  /* Init slave mode. Enables master too
+  * We are going to configure the slave device to
+  *  - enable fast I2C (400khz)
+  *  - dual addresses (can have 2 addresses per module)
+  * general call (accepts data writes to 0x00 on a broadcast basis)
+  *
+  * If the buffered example is enabled, then we also enable the
+  * buffer for rx and tx.
+  * Note you can independently enable/disable RX and TX buffers to
+  * allow a buffered read and direct writes. Useful if you don't know how
+  * much the master will read.
+  */
+  #if USE_BUFFERED_EXAMPLE == 1
+  i2c_slave_enable(I2C1, I2C_FAST_MODE | I2C_SLAVE_DUAL_ADDRESS | I2C_SLAVE_GENERAL_CALL | I2C_SLAVE_USE_RX_BUFFER | I2C_SLAVE_USE_TX_BUFFER);
+  #else
+  i2c_slave_enable(I2C1, I2C_FAST_MODE | I2C_SLAVE_DUAL_ADDRESS | I2C_SLAVE_GENERAL_CALL);
+  #endif
+
+  // attach  receive handler
+  i2c_slave_attach_recv_handler(I2C1, &msg, funcrx);
+  // attach transmit handler
+  i2c_slave_attach_transmit_handler(I2C1, &msg, functx);
+
+  // set addresss to 4
+  i2c_slave_set_own_address(I2C1, 4);
+}
+
+void loop() {
+  static uint32_t lastMessage = millis();
+
+  // This is potentially dangerous.
+  // We're reading from the live buffer, the content can change
+  // in the middle of Serial.println
+
+  if (newMessage && strlen(bufferAsChar)==6) {
+    for (int i=0; i<5; i++) {
+      // Print as char
+      Serial.print(bufferAsChar[i]);
+    }
+    // Print as byte
+    Serial.println(buffer[5]);
+    lastMessage = millis();
+    newMessage = false;
+  } else {
+    if(newMessage && strlen(bufferAsChar)!=6) {
+      // this also happends on the line "x is 0"
+      Serial.print("Bad data received:");
+      Serial.println(bufferAsChar);
+      Serial.print("strlen:");
+      Serial.println(strlen(bufferAsChar));
+      newMessage = false;
+    } else
+    if(millis() - lastMessage > 3000){
+      Serial.println("Nothing received in 3 seconds.");
+      lastMessage = millis();
+    }
+  }
+}

STM32F1/libraries/WireSlave/examples/master_reader/master_reader.ino

@@ -0,0 +1,32 @@
+// Wire Master Reader
+// by Nicholas Zambetti <http://www.zambetti.com>
+
+// Demonstrates use of the Wire library
+// Reads data from an I2C/TWI slave device
+// Refer to the "Wire Slave Sender" example for use with this
+
+// Created 29 March 2006
+
+// This example code is in the public domain.
+
+
+#include <Wire_slave.h>
+
+void setup()
+{
+  Wire.begin();        // join i2c bus (address optional for master)
+  Serial.begin(9600);  // start serial for output
+}
+
+void loop()
+{
+  Wire.requestFrom(2, 6);    // request 6 bytes from slave device #2
+
+  while(Wire.available())    // slave may send less than requested
+  {
+    char c = Wire.read(); // receive a byte as character
+    Serial.print(c);         // print the character
+  }
+
+  delay(500);
+}

STM32F1/libraries/WireSlave/examples/master_writer/master_writer.ino

@@ -0,0 +1,31 @@
+// Wire Master Writer
+// by Nicholas Zambetti <http://www.zambetti.com>
+
+// Demonstrates use of the Wire library
+// Writes data to an I2C/TWI slave device
+// Refer to the "Wire Slave Receiver" example for use with this
+
+// Created 29 March 2006
+
+// This example code is in the public domain.
+
+
+#include <Wire_slave.h>
+
+void setup()
+{
+  Wire.begin(); // join i2c bus (address optional for master)
+}
+
+byte x = 0;
+
+void loop()
+{
+  Wire.beginTransmission(4); // transmit to device #4
+  Wire.write("x is ");        // sends five bytes
+  Wire.write(x);              // sends one byte
+  Wire.endTransmission();    // stop transmitting
+
+  x++;
+  delay(500);
+}

STM32F1/libraries/WireSlave/examples/slave_receiver/slave_receiver.ino

@@ -0,0 +1,38 @@
+// Wire Slave Receiver
+// by Nicholas Zambetti <http://www.zambetti.com>
+
+// Demonstrates use of the Wire library
+// Receives data as an I2C/TWI slave device
+// Refer to the "Wire Master Writer" example for use with this
+
+// Created 29 March 2006
+
+// This example code is in the public domain.
+
+
+#include <Wire_slave.h>
+
+void setup()
+{
+  Wire.begin(4);                // join i2c bus with address #4
+  Wire.onReceive(receiveEvent); // register event
+  Serial.begin(9600);           // start serial for output
+}
+
+void loop()
+{
+  delay(100);
+}
+
+// function that executes whenever data is received from master
+// this function is registered as an event, see setup()
+void receiveEvent(int howMany)
+{
+  while(1 < Wire.available()) // loop through all but the last
+  {
+    char c = Wire.read(); // receive byte as a character
+    Serial.print(c);         // print the character
+  }
+  int x = Wire.read();    // receive byte as an integer
+  Serial.println(x);         // print the integer
+}

STM32F1/libraries/WireSlave/examples/slave_sender/slave_sender.ino

@@ -0,0 +1,32 @@
+// Wire Slave Sender
+// by Nicholas Zambetti <http://www.zambetti.com>
+
+// Demonstrates use of the Wire library
+// Sends data as an I2C/TWI slave device
+// Refer to the "Wire Master Reader" example for use with this
+
+// Created 29 March 2006
+
+// This example code is in the public domain.
+
+
+#include <Wire_slave.h>
+
+void setup()
+{
+  Wire.begin(2);                // join i2c bus with address #2
+  Wire.onRequest(requestEvent); // register event
+}
+
+void loop()
+{
+  delay(100);
+}
+
+// function that executes whenever data is requested by master
+// this function is registered as an event, see setup()
+void requestEvent()
+{
+  Wire.write("hello "); // respond with message of 6 bytes
+                       // as expected by master
+}

STM32F1/libraries/WireSlave/library.properties

@@ -0,0 +1,11 @@
+name=Wire_Slave
+version=1.0
+author=
+email=
+sentence=Wire with slave support
+paragraph=Experimental Wire with slave support
+url=
+architectures=STM32F1
+maintainer=
+category=Communication
+include=src/Wire_Slave.h

STM32F1/libraries/WireSlave/src/Wire.h

@@ -0,0 +1 @@
+#error "Something is trying to include Wire_slave.h when Wire.h is already included, they are mutually exclusive"

STM32F1/libraries/WireSlave/src/Wire_slave.cpp

@@ -0,0 +1,106 @@
+/******************************************************************************
+ * The MIT License
+ *
+ * Copyright (c) 2010 LeafLabs LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *****************************************************************************/
+
+/**
+ * @file TwoWire.cpp
+ * @author Trystan Jones <crenn6977@gmail.com>
+ * @brief Wire library, uses the hardware I2C available in the Maple to
+ *        interact with I2C slave devices.
+ */
+
+/*
+ * Library created by crenn to use the new WireBase system and allow Arduino
+ * users easy interaction with the I2C Hardware in a familiar method.
+ */
+
+#include "Wire_slave.h"
+
+uint8 TwoWire::process(uint8 stop) {
+    int8 res = i2c_master_xfer(sel_hard, &itc_msg, 1, 0);
+    if (res == I2C_ERROR_PROTOCOL) {
+        if (sel_hard->error_flags & I2C_SR1_AF) { /* NACK */
+            res = (sel_hard->error_flags & I2C_SR1_ADDR ? ENACKADDR :
+                                                          ENACKTRNS);
+        } else if (sel_hard->error_flags & I2C_SR1_OVR) { /* Over/Underrun */
+            res = EDATA;
+        } else { /* Bus or Arbitration error */
+            res = EOTHER;
+        }
+        i2c_disable(sel_hard);
+        i2c_master_enable(sel_hard, (I2C_BUS_RESET | dev_flags));
+    }
+    return res;
+}
+
+uint8 TwoWire::process(){
+	return process(true);
+}
+
+// TODO: Add in Error Handling if devsel is out of range for other Maples
+TwoWire::TwoWire(uint8 dev_sel, uint8 flags) {
+    if (dev_sel == 1) {
+        sel_hard = I2C1;
+    } else if (dev_sel == 2) {
+        sel_hard = I2C2;
+    } else {
+        ASSERT(1);
+    }
+    dev_flags = flags;
+}
+
+TwoWire::~TwoWire() {
+    i2c_disable(sel_hard);
+    sel_hard = 0;
+}
+
+void TwoWire::begin(uint8 self_addr) {
+    i2c_master_enable(sel_hard, dev_flags);
+}
+
+void TwoWire::end() {
+    i2c_disable(sel_hard);
+    sel_hard = 0;
+}
+
+void TwoWire::setClock(uint32_t frequencyHz)
+{
+	switch(frequencyHz)
+	{
+		case 400000:
+			dev_flags |= I2C_FAST_MODE;// set FAST_MODE bit
+			break;
+		case 100000:
+		default:
+			dev_flags &= ~I2C_FAST_MODE;// clear FAST_MODE bit
+			break;
+	}
+	if (sel_hard->regs->CR1 & I2C_CR1_PE){
+	    i2c_disable(sel_hard);
+	    i2c_master_enable(sel_hard, dev_flags);
+	}
+}
+
+TwoWire Wire(1);

STM32F1/libraries/WireSlave/src/Wire_slave.h

@@ -0,0 +1,78 @@
+/******************************************************************************
+ * The MIT License
+ *
+ * Copyright (c) 2010 LeafLabs LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *****************************************************************************/
+
+/**
+ * @file Wire.h
+ * @author Trystan Jones <crenn6977@gmail.com>
+ * @brief Wire library, uses the hardware I2C available in the Maple to
+ *        interact with I2C slave devices.
+ */
+
+/*
+ * Library created by crenn to use the new WireBase system and allow Arduino
+ * users easy interaction with the I2C Hardware in a familiar method.
+ */
+
+#ifndef _TWOWIRE_H_
+#define _TWOWIRE_H_
+
+#include "utility/WireBase_slave.h"
+#include "wirish.h"
+#include <libmaple/i2c_slave.h>
+
+class TwoWire : public WireBase {
+private:
+    i2c_dev* sel_hard;
+    uint8    dev_flags;
+protected:
+    /*
+     * Processes the incoming I2C message defined by WireBase to the
+     * hardware. If an error occured, restart the I2C device.
+     */
+    uint8 process(uint8);
+    uint8 process();
+public:
+    /*
+     * Check if devsel is within range and enable selected I2C interface with
+     * passed flags
+     */
+    TwoWire(uint8, uint8 = 0);
+
+	/*
+	 * Shuts down (disables) the hardware I2C
+	 */
+	void end();
+
+	void setClock(uint32_t frequencyHz);
+    /*
+     * Disables the I2C device and remove the device address.
+     */
+    ~TwoWire();
+
+    void begin(uint8 = 0x00);
+};
+extern TwoWire Wire;
+#endif // _TWOWIRE_H_

STM32F1/libraries/WireSlave/src/i2c_slave.c

@@ -0,0 +1,789 @@
+/******************************************************************************
+ * The MIT License
+ *
+ * Copyright (c) 2010 Perry Hung.
+ * Copyright (c) 2012 LeafLabs, LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *****************************************************************************/
+
+/**
+ * @file libmaple/i2c.c
+ * @author Perry Hung <perry@leaflabs.com>
+ * @author Barry Carter <barry.carter@gmail.com>
+ * @brief Inter-Integrated Circuit (I2C) support.
+ *
+ * Master and Slave supported
+ * I2C slave support added 2012 by Barry Carter. barry.carter@gmail.com, headfuzz.co.uk
+ */
+
+#include "libmaple/i2c_common_slave.h"
+
+#include "i2c_private.h"
+
+
+#include "libmaple/i2c_slave.h"
+#include <libmaple/libmaple.h>
+#include <libmaple/rcc.h>
+#include <libmaple/gpio.h>
+#include <libmaple/nvic.h>
+#include <libmaple/systick.h>
+
+#include <string.h>
+
+static inline int32 wait_for_state_change(i2c_dev *dev,
+                                          i2c_state state,
+                                          uint32 timeout);
+static void set_ccr_trise(i2c_dev *dev, uint32 flags);
+
+/**
+ * @brief Fill data register with slave address
+ * @param dev I2C device
+ * @param addr Slave address
+ * @param rw Read/write bit
+ */
+static inline void i2c_send_slave_addr(i2c_dev *dev, uint32 addr, uint32 rw) {
+    dev->regs->DR = (addr << 1) | rw;
+}
+
+/*
+ * Simple debugging trail. Define I2C_DEBUG to turn on.
+ */
+#ifdef I2C_DEBUG
+
+#define NR_CRUMBS       128
+static struct crumb crumbs[NR_CRUMBS];
+static uint32 cur_crumb = 0;
+
+static inline void i2c_drop_crumb(uint32 event, uint32 arg0, uint32 arg1) {
+    if (cur_crumb < NR_CRUMBS) {
+        struct crumb *crumb = &crumbs[cur_crumb++];
+        crumb->event = event;
+        crumb->arg0 = arg0;
+        crumb->arg1 = arg1;
+    }
+}
+#define I2C_CRUMB(event, arg0, arg1) i2c_drop_crumb(event, arg0, arg1)
+
+#else
+#define I2C_CRUMB(event, arg0, arg1)
+#endif
+
+struct crumb {
+    uint32 event;
+    uint32 arg0;
+    uint32 arg1;
+};
+
+enum {
+    IRQ_ENTRY           = 1,
+    TXE_ONLY            = 2,
+    TXE_BTF             = 3,
+    STOP_SENT           = 4,
+    TEST                = 5,
+    RX_ADDR_START       = 6,
+    RX_ADDR_STOP        = 7,
+    RXNE_ONLY           = 8,
+    RXNE_SENDING        = 9,
+    RXNE_START_SENT     = 10,
+    RXNE_STOP_SENT      = 11,
+    RXNE_DONE           = 12,
+    ERROR_ENTRY         = 13,
+};
+
+/**
+ * @brief Reset an I2C bus.
+ *
+ * Reset is accomplished by clocking out pulses until any hung slaves
+ * release SDA and SCL, then generating a START condition, then a STOP
+ * condition.
+ *
+ * @param dev I2C device
+ */
+void i2c_bus_reset(const i2c_dev *dev) {
+    /* Release both lines */
+    i2c_master_release_bus(dev);
+
+    /*
+     * Make sure the bus is free by clocking it until any slaves release the
+     * bus.
+     */
+    while (!gpio_read_bit(sda_port(dev), dev->sda_pin)) {
+        /* Wait for any clock stretching to finish */
+        while (!gpio_read_bit(scl_port(dev), dev->scl_pin))
+            ;
+        delay_us(10);
+
+        /* Pull low */
+        gpio_write_bit(scl_port(dev), dev->scl_pin, 0);
+        delay_us(10);
+
+        /* Release high again */
+        gpio_write_bit(scl_port(dev), dev->scl_pin, 1);
+        delay_us(10);
+    }
+
+    /* Generate start then stop condition */
+    gpio_write_bit(sda_port(dev), dev->sda_pin, 0);
+    delay_us(10);
+    gpio_write_bit(scl_port(dev), dev->scl_pin, 0);
+    delay_us(10);
+    gpio_write_bit(scl_port(dev), dev->scl_pin, 1);
+    delay_us(10);
+    gpio_write_bit(sda_port(dev), dev->sda_pin, 1);
+}
+
+/**
+ * @brief Initialize an I2C device and reset its registers to their
+ *        default values.
+ * @param dev Device to initialize.
+ */
+void i2c_init(i2c_dev *dev) {
+    rcc_reset_dev(dev->clk_id);
+    rcc_clk_enable(dev->clk_id);
+    _i2c_irq_priority_fixup(dev);
+}
+
+/* Hack for deprecated bit of STM32F1 functionality */
+#ifndef _I2C_HAVE_DEPRECATED_I2C_REMAP
+#define _i2c_handle_remap(dev, flags) ((void)0)
+#endif
+
+/**
+ * @brief Initialize an I2C device as bus master
+ * @param dev Device to enable
+ * @param flags Bitwise or of the following I2C options:
+ *              I2C_FAST_MODE: 400 khz operation,
+ *              I2C_DUTY_16_9: 16/9 Tlow/Thigh duty cycle (only applicable for
+ *                             fast mode),
+ *              I2C_BUS_RESET: Reset the bus and clock out any hung slaves on
+ *                             initialization,
+ *              I2C_10BIT_ADDRESSING: Enable 10-bit addressing,
+ *              I2C_REMAP: (deprecated, STM32F1 only) Remap I2C1 to SCL/PB8
+ *                         SDA/PB9.
+ */
+void i2c_master_enable(i2c_dev *dev, uint32 flags) {
+    /* PE must be disabled to configure the device */
+    ASSERT(!(dev->regs->CR1 & I2C_CR1_PE));
+
+    /* Ugh */
+    _i2c_handle_remap(dev, flags);
+
+    /* Reset the bus. Clock out any hung slaves. */
+    if (flags & I2C_BUS_RESET) {
+        i2c_bus_reset(dev);
+    }
+
+    /* Turn on clock and set GPIO modes */
+    i2c_init(dev);
+    i2c_config_gpios(dev);
+
+    /* Configure clock and rise time */
+    set_ccr_trise(dev, flags);
+
+    /* Enable event and buffer interrupts */
+    nvic_irq_enable(dev->ev_nvic_line);
+    nvic_irq_enable(dev->er_nvic_line);
+    i2c_enable_irq(dev, I2C_IRQ_EVENT | I2C_IRQ_BUFFER | I2C_IRQ_ERROR);
+
+    /* Configure the slave unit */
+    if (flags & I2C_SLAVE_DUAL_ADDRESS) {
+        i2c_slave_dual_address_enable(dev);
+    }
+
+    if (flags & I2C_SLAVE_GENERAL_CALL) {
+        i2c_slave_general_call_enable(dev);
+    }
+
+    /* store all of the flags */
+    dev->config_flags = flags;
+
+    /* Make it go! */
+    i2c_peripheral_enable(dev);
+    i2c_enable_ack(dev);
+
+    dev->state = I2C_STATE_IDLE;
+}
+
+/**
+ * @brief Initialize an I2C device as slave (and master)
+ * @param dev Device to enable
+ * @param flags Bitwise or of the following I2C options:
+ *              I2C_FAST_MODE: 400 khz operation,
+ *              I2C_DUTY_16_9: 16/9 Tlow/Thigh duty cycle (only applicable for
+ *                             fast mode),
+ *              I2C_BUS_RESET: Reset the bus and clock out any hung slaves on
+ *                             initialization,
+ *              I2C_10BIT_ADDRESSING: Enable 10-bit addressing,
+ *              I2C_REMAP: (deprecated, STM32F1 only) Remap I2C1 to SCL/PB8
+ *                         SDA/PB9.
+ *              I2C_SLAVE_DUAL_ADDRESS: Slave can respond on 2 i2C addresses
+ *              I2C_SLAVE_GENERAL_CALL: SLA+W broadcast to all general call
+ *                                      listeners on bus. Addr 0x00
+ *              I2C_SLAVE_USE_RX_BUFFER: Use a buffer to receive the incoming
+ *                                       data. Callback at end of recv
+ *              I2C_SLAVE_USE_TX_BUFFER: Use a buffer to transmit data.
+ *                                       Callback will be called before tx
+ */
+void i2c_slave_enable(i2c_dev *dev, uint32 flags) {
+    i2c_disable(dev);
+    i2c_master_enable(dev, dev->config_flags | flags);
+}
+
+/**
+ * @brief Process an i2c transaction.
+ *
+ * Transactions are composed of one or more i2c_msg's, and may be read
+ * or write tranfers.  Multiple i2c_msg's will generate a repeated
+ * start in between messages.
+ *
+ * @param dev I2C device
+ * @param msgs Messages to send/receive
+ * @param num Number of messages to send/receive
+ * @param timeout Bus idle timeout in milliseconds before aborting the
+ *                transfer.  0 denotes no timeout.
+ * @return 0 on success,
+ *         I2C_ERROR_PROTOCOL if there was a protocol error,
+ *         I2C_ERROR_TIMEOUT if the transfer timed out.
+ */
+int32 i2c_master_xfer(i2c_dev *dev,
+                      i2c_msg *msgs,
+                      uint16 num,
+                      uint32 timeout) {
+    int32 rc;
+
+    ASSERT(dev->state == I2C_STATE_IDLE);
+
+    dev->msg = msgs;
+    dev->msgs_left = num;
+    dev->timestamp = systick_uptime();
+    dev->state = I2C_STATE_BUSY;
+
+    i2c_enable_irq(dev, I2C_IRQ_EVENT);
+    i2c_start_condition(dev);
+
+    rc = wait_for_state_change(dev, I2C_STATE_XFER_DONE, timeout);
+    if (rc < 0) {
+        goto out;
+    }
+
+    dev->state = I2C_STATE_IDLE;
+out:
+    return rc;
+}
+
+/**
+ * @brief Wait for an I2C event, or time out in case of error.
+ * @param dev I2C device
+ * @param state I2C_state state to wait for
+ * @param timeout Timeout, in milliseconds
+ * @return 0 if target state is reached, a negative value on error.
+ */
+static inline int32 wait_for_state_change(i2c_dev *dev,
+                                          i2c_state state,
+                                          uint32 timeout) {
+    i2c_state tmp;
+
+    while (1) {
+        tmp = dev->state;
+
+        if (tmp == I2C_STATE_ERROR) {
+            return I2C_STATE_ERROR;
+        }
+
+        if (tmp == state) {
+            return 0;
+        }
+
+        if (timeout) {
+            if (systick_uptime() > (dev->timestamp + timeout)) {
+                /* TODO: overflow? */
+                /* TODO: racy? */
+                return I2C_ERROR_TIMEOUT;
+            }
+        }
+    }
+}
+
+/*
+ * Private API
+ */
+
+/*
+ * IRQ handler for I2C master. Handles transmission/reception.
+ */
+void _i2c_irq_handler(i2c_dev *dev) {
+    /* WTFs:
+     * - Where is I2C_MSG_10BIT_ADDR handled?
+     */
+    i2c_msg *msg = dev->msg;
+
+    uint8 read = msg->flags & I2C_MSG_READ;
+
+    uint32 sr1 = dev->regs->SR1;
+    uint32 sr2 = dev->regs->SR2;
+    I2C_CRUMB(IRQ_ENTRY, sr1, sr2);
+
+    /*
+     * Reset timeout counter
+     */
+    dev->timestamp = systick_uptime();
+
+    /*
+     * Add Slave support
+     */
+
+    /* Check to see if MSL master slave bit is set */
+    if ((sr2 & I2C_SR2_MSL) != I2C_SR2_MSL) { /* 0 = slave mode 1 = master */
+
+        /* Check for address match */
+        if (sr1 & I2C_SR1_ADDR) {
+            /* Find out which address was matched */
+            /* Check the general call address first */
+            if (sr2 & I2C_SR2_GENCALL) {
+                dev->i2c_slave_msg->addr = 0;
+            }
+            /* We matched the secondary address */
+            else if (sr2 & I2C_SR2_DUALF) {
+                dev->i2c_slave_msg->addr = dev->regs->OAR2 & 0xFE;
+            }
+            /* We matched the primary address */
+            else if ((sr2 & I2C_SR2_DUALF) != I2C_SR2_DUALF) {
+                dev->i2c_slave_msg->addr = dev->regs->OAR1 & 0xFE;
+            }
+            /* Shouldn't get here */
+            else {
+                dev->i2c_slave_msg->addr = -1; /* uh oh */
+            }
+
+            /* if we have buffered io */
+            if ((dev->config_flags & I2C_SLAVE_USE_RX_BUFFER) ||
+                (dev->config_flags & I2C_SLAVE_USE_TX_BUFFER)) {
+
+                /* if receiving then this would be a repeated start
+                 *
+                 *if we have some bytes already
+                 */
+                if ((dev->state == I2C_STATE_SL_RX) &&
+                    (dev->i2c_slave_msg->xferred > 0)  &&
+                    (dev->config_flags & I2C_SLAVE_USE_RX_BUFFER)) {
+                    /* Call the callback with the contents of the data */
+                    if (dev->i2c_slave_recv_callback != NULL) {
+                        (*(dev->i2c_slave_recv_callback))(dev->i2c_slave_msg);
+                    }
+                }
+
+                /* Reset the message back to defaults.
+                 * We are starting a new message
+                 */
+                dev->i2c_slave_msg->flags = 0;
+                dev->i2c_slave_msg->length = 0;
+                dev->i2c_slave_msg->xferred = 0;
+                dev->msgs_left = 0;
+                dev->timestamp = systick_uptime();
+
+                /* We have been addressed with SLA+R so
+                 * the master wants us to transmit
+                 */
+                if ((sr1 & I2C_SR1_TXE) &&
+                    (dev->config_flags & I2C_SLAVE_USE_TX_BUFFER)) {
+                    /* Call the transmit callback so it can populate the msg
+                     * data with the bytes to go
+                     */
+                    if (dev->i2c_slave_transmit_callback != NULL) {
+                        (*(dev->i2c_slave_transmit_callback))(dev->i2c_slave_msg);
+                    }
+                }
+                dev->state = I2C_STATE_BUSY;
+            }
+
+            sr1 = sr2 = 0;
+        }
+
+         /* EV3: Master requesting data from slave. Transmit a byte*/
+        if (sr1 & I2C_SR1_TXE) {
+            if (dev->config_flags & I2C_SLAVE_USE_TX_BUFFER) {
+                if (dev->i2c_slave_msg->xferred >= dev->i2c_slave_msg->length) {
+                    /* End of the transmit buffer? If so we NACK */
+                    i2c_disable_ack(dev);
+                    /* We have to either issue a STOP or write something here.
+                     * STOP here seems to screw up some masters,
+                     * For now padding with 0
+                     */
+                    i2c_write(dev, 0);
+                    /*i2c_stop_condition(dev); // This is causing bus lockups way more than it should !? Seems some I2C master devices freak out here*/
+                }
+                else
+                {
+                    /* NACk the last byte */
+                    if (dev->i2c_slave_msg->xferred == dev->i2c_slave_msg->length-1) {
+                        i2c_disable_ack(dev);
+                    }
+                    else {
+                        i2c_enable_ack(dev);
+                    }
+                    i2c_write(dev, dev->i2c_slave_msg->data[dev->i2c_slave_msg->xferred++]);
+                }
+            }
+            else
+            {
+                /* Call the callback to get the data we need.
+                 * The callback is expected to write using i2c_write(...)
+                 * If the slave is going to terminate the transfer, this function should
+                 * also do a NACK on the last byte!
+                 */
+                if (dev->i2c_slave_transmit_callback != NULL) (*(dev->i2c_slave_transmit_callback))(dev->i2c_slave_msg);
+            }
+
+            dev->state = I2C_STATE_BUSY;
+            sr1 = sr2 = 0;
+        }
+
+        /* EV2: Slave received data from a master. Get from DR */
+        if (sr1 & I2C_SR1_RXNE) {
+            if (dev->config_flags & I2C_SLAVE_USE_RX_BUFFER) {
+                /* Fill the buffer with the contents of the data register */
+                /* These is potential for buffer overflow here, so we should
+                 * really store the size of the array. This is expensive in
+                 * the ISR so left out for now. We must trust the implementor!
+                 */
+                dev->i2c_slave_msg->data[dev->i2c_slave_msg->xferred++] = dev->regs->DR;
+                dev->i2c_slave_msg->length++;
+            }
+            else  {
+                /* Call the callback with the contents of the data */
+                dev->i2c_slave_msg->data[0] = dev->regs->DR;
+                if (dev->i2c_slave_recv_callback != NULL) (*(dev->i2c_slave_recv_callback))(dev->i2c_slave_msg);
+            }
+            dev->state = I2C_STATE_SL_RX;
+            sr1 = sr2 = 0;
+        }
+
+        /* EV4: Slave has detected a STOP condition on the bus */
+        if (sr1 & I2C_SR1_STOPF) {
+            dev->regs->CR1 |= I2C_CR1_PE;
+
+            if ((dev->config_flags & I2C_SLAVE_USE_RX_BUFFER) ||
+                (dev->config_flags & I2C_SLAVE_USE_TX_BUFFER)) {
+
+                /* The callback with the data will happen on a NACK of the last data byte.
+                 * This is handled in the error IRQ (AF bit)
+                 */
+                /* Handle the case where the master misbehaves by sending no NACK */
+                if (dev->state != I2C_STATE_IDLE) {
+                    if (dev->state == I2C_STATE_SL_RX) {
+                        if (dev->i2c_slave_recv_callback != NULL) (*(dev->i2c_slave_recv_callback))(dev->i2c_slave_msg);
+                    }
+                    else {
+                        if (dev->i2c_slave_transmit_callback != NULL) (*(dev->i2c_slave_transmit_callback))(dev->i2c_slave_msg);
+                    }
+                }
+            }
+
+            sr1 = sr2 = 0;
+            dev->state = I2C_STATE_IDLE;
+        }
+
+        return;
+    }
+
+    /*
+     * EV5: Start condition sent
+     */
+    if (sr1 & I2C_SR1_SB) {
+        msg->xferred = 0;
+        i2c_enable_irq(dev, I2C_IRQ_BUFFER);
+
+        /*
+         * Master receiver
+         */
+        if (read) {
+            i2c_enable_ack(dev);
+        }
+
+        i2c_send_slave_addr(dev, msg->addr, read);
+        sr1 = sr2 = 0;
+    }
+
+    /*
+     * EV6: Slave address sent
+     */
+    if (sr1 & I2C_SR1_ADDR) {
+        /*
+         * Special case event EV6_1 for master receiver.
+         * Generate NACK and restart/stop condition after ADDR
+         * is cleared.
+         */
+        if (read) {
+            if (msg->length == 1) {
+                i2c_disable_ack(dev);
+                if (dev->msgs_left > 1) {
+                    i2c_start_condition(dev);
+                    I2C_CRUMB(RX_ADDR_START, 0, 0);
+                } else {
+                    i2c_stop_condition(dev);
+                    I2C_CRUMB(RX_ADDR_STOP, 0, 0);
+                }
+            }
+        } else {
+            /*
+             * Master transmitter: write first byte to fill shift
+             * register.  We should get another TXE interrupt
+             * immediately to fill DR again.
+             */
+            if (msg->length > 1) {
+                i2c_write(dev, msg->data[msg->xferred++]);
+            } else if (msg->length == 0) { /* We're just sending an address */
+                i2c_stop_condition(dev);
+              /*
+               * Turn off event interrupts to keep BTF from firing until
+               * the end of the stop condition. Why on earth they didn't
+               * have a start/stop condition request clear BTF is beyond
+               * me.
+               */
+              i2c_disable_irq(dev, I2C_IRQ_EVENT);
+              I2C_CRUMB(STOP_SENT, 0, 0);
+              dev->state = I2C_STATE_XFER_DONE;
+            } /* else we're just sending one byte */
+        }
+        sr1 = sr2 = 0;
+    }
+
+    /*
+     * EV8: Master transmitter
+     * Transmit buffer empty, but we haven't finished transmitting the last
+     * byte written.
+     */
+    if ((sr1 & I2C_SR1_TXE) && !(sr1 & I2C_SR1_BTF)) {
+        I2C_CRUMB(TXE_ONLY, 0, 0);
+        if (dev->msgs_left) {
+            i2c_write(dev, msg->data[msg->xferred++]);
+            if (msg->xferred == msg->length) {
+                /*
+                 * End of this message. Turn off TXE/RXNE and wait for
+                 * BTF to send repeated start or stop condition.
+                 */
+                i2c_disable_irq(dev, I2C_IRQ_BUFFER);
+                dev->msgs_left--;
+            }
+        } else {
+            /*
+             * This should be impossible...
+             */
+            ASSERT(0);
+        }
+        sr1 = sr2 = 0;
+    }
+
+    /*
+     * EV8_2: Master transmitter
+     * Last byte sent, program repeated start/stop
+     */
+    if ((sr1 & I2C_SR1_TXE) && (sr1 & I2C_SR1_BTF)) {
+        I2C_CRUMB(TXE_BTF, 0, 0);
+        if (dev->msgs_left) {
+            I2C_CRUMB(TEST, 0, 0);
+            /*
+             * Repeated start insanity: We can't disable ITEVTEN or else SB
+             * won't interrupt, but if we don't disable ITEVTEN, BTF will
+             * continually interrupt us. What the fuck ST?
+             */
+            i2c_start_condition(dev);
+            while (!(dev->regs->SR1 & I2C_SR1_SB))
+                ;
+            dev->msg++;
+        } else {
+            i2c_stop_condition(dev);
+
+            /*
+             * Turn off event interrupts to keep BTF from firing until
+             * the end of the stop condition. Why on earth they didn't
+             * have a start/stop condition request clear BTF is beyond
+             * me.
+             */
+            i2c_disable_irq(dev, I2C_IRQ_EVENT);
+            I2C_CRUMB(STOP_SENT, 0, 0);
+            dev->state = I2C_STATE_XFER_DONE;
+        }
+        sr1 = sr2 = 0;
+    }
+
+    /*
+     * EV7: Master Receiver
+     */
+    if (sr1 & I2C_SR1_RXNE) {
+        I2C_CRUMB(RXNE_ONLY, 0, 0);
+        msg->data[msg->xferred++] = dev->regs->DR;
+
+        /*
+         * EV7_1: Second to last byte in the reception? Set NACK and generate
+         * stop/restart condition in time for the last byte. We'll get one more
+         * RXNE interrupt before shutting things down.
+         */
+        if (msg->xferred == (msg->length - 1)) {
+            i2c_disable_ack(dev);
+            if (dev->msgs_left > 2) {
+                i2c_start_condition(dev);
+                I2C_CRUMB(RXNE_START_SENT, 0, 0);
+            } else {
+                i2c_stop_condition(dev);
+                I2C_CRUMB(RXNE_STOP_SENT, 0, 0);
+            }
+        } else if (msg->xferred == msg->length) {
+            dev->msgs_left--;
+            if (dev->msgs_left == 0) {
+                /*
+                 * We're done.
+                 */
+                I2C_CRUMB(RXNE_DONE, 0, 0);
+                dev->state = I2C_STATE_XFER_DONE;
+            } else {
+                dev->msg++;
+            }
+        }
+    }
+}
+
+/*
+ * Interrupt handler for I2C error conditions. Aborts any pending I2C
+ * transactions.
+ */
+void _i2c_irq_error_handler(i2c_dev *dev) {
+    I2C_CRUMB(ERROR_ENTRY, dev->regs->SR1, dev->regs->SR2);
+
+    dev->error_flags = dev->regs->SR1 & (I2C_SR1_BERR |
+                                         I2C_SR1_ARLO |
+                                         I2C_SR1_AF |
+                                         I2C_SR1_OVR);
+
+    /* Are we in slave mode? */
+    if ((dev->regs->SR2 & I2C_SR2_MSL) != I2C_SR2_MSL) {
+        /* Check to see if the master device did a NAK on the last bit
+         * This is perfectly valid for a master to do this on the bus.
+         * We ignore this. Any further error processing takes us into dead
+         * loop waiting for the stop condition that will never arrive
+         */
+        if (dev->regs->SR1 & I2C_SR1_AF) {
+            /* Clear flags */
+            dev->regs->SR1 = 0;
+            dev->regs->SR2 = 0;
+            /* We need to write something to CR1 to clear the flag.
+             * This isn't really mentioned but seems important */
+            i2c_enable_ack(dev);
+
+            if (dev->state == I2C_STATE_SL_RX &&
+                dev->config_flags & I2C_SLAVE_USE_RX_BUFFER &&
+                dev->i2c_slave_msg->xferred > 0) {
+                /* Call the callback with the contents of the data */
+                if (dev->i2c_slave_recv_callback != NULL) (*(dev->i2c_slave_recv_callback))(dev->i2c_slave_msg);
+            }
+
+            dev->state = I2C_STATE_IDLE;
+            return;
+        }
+        /* Catch any other strange errors while in slave mode.
+         * I have seen BERR caused by an over fast master device
+         * as well as several overflows and arbitration failures.
+         * We are going to reset SR flags and carry on at this point which
+         * is not the best thing to do, but stops the bus locking up completely
+         * If we carry on below and send the stop bit, the code spins forever */
+        /* Clear flags */
+        dev->regs->SR1 = 0;
+        dev->regs->SR2 = 0;
+        dev->state = I2C_STATE_IDLE;
+        return;
+    }
+
+    /* Clear flags */
+    dev->regs->SR1 = 0;
+    dev->regs->SR2 = 0;
+
+    i2c_stop_condition(dev);
+    i2c_disable_irq(dev, I2C_IRQ_BUFFER | I2C_IRQ_EVENT | I2C_IRQ_ERROR);
+    dev->state = I2C_STATE_ERROR;
+}
+
+/*
+ * CCR/TRISE configuration helper
+ */
+static void set_ccr_trise(i2c_dev *dev, uint32 flags) {
+    uint32 ccr     = 0;
+    uint32 trise   = 0;
+    uint32 clk_mhz = _i2c_bus_clk(dev);
+    uint32 clk_hz  = clk_mhz * (1000 * 1000);
+
+    i2c_set_input_clk(dev, clk_mhz);
+
+    if (flags & I2C_FAST_MODE) {
+        ccr |= I2C_CCR_FS;
+
+        if (flags & I2C_DUTY_16_9) {
+            /* Tlow/Thigh = 16/9 */
+            ccr |= I2C_CCR_DUTY_16_9;
+            ccr |= clk_hz / (400000 * 25);
+        } else {
+            /* Tlow/Thigh = 2 */
+            ccr |= clk_hz / (400000 * 3);
+        }
+
+        trise = (300 * clk_mhz / 1000) + 1;
+    } else {
+        /* Tlow/Thigh = 1 */
+        ccr = clk_hz / (100000 * 2);
+        trise = clk_mhz + 1;
+    }
+
+    /* Set minimum required value if CCR < 1*/
+    if ((ccr & I2C_CCR_CCR) == 0) {
+        ccr |= 0x1;
+    }
+
+    i2c_set_clk_control(dev, ccr);
+    i2c_set_trise(dev, trise);
+}
+
+
+/**
+ * @brief callback for when the device acts as a slave. If using an rx buffer, this is triggered
+ * after the last byte, otherwise it is called for every incoming packet.
+ * @param dev I2C device
+ * @param msg The dev_msg to pass to the slave init code
+ * @param func The function pointer to call
+ */
+void i2c_slave_attach_recv_handler(i2c_dev *dev, i2c_msg *msg, i2c_slave_recv_callback_func func) {
+    dev->i2c_slave_recv_callback = func;
+    dev->i2c_slave_msg = msg;
+    msg->xferred = 0;
+}
+
+
+/**
+ * @brief callback for when the device acts as a slave. If using a tx buffer, this is triggered
+ * after the device is successsfully addressed with SLA+R.
+ * @param dev I2C device
+ * @param msg The dev_msg to pass to the slave init code
+ * @param func The function pointer to call
+ */
+void i2c_slave_attach_transmit_handler(i2c_dev *dev, i2c_msg *msg, i2c_slave_transmit_callback_func func) {
+    dev->i2c_slave_transmit_callback = func;
+    dev->i2c_slave_msg = msg;
+    msg->xferred = 0;
+}

STM32F1/libraries/WireSlave/src/libmaple/i2c_common_slave.h

@@ -0,0 +1,110 @@
+/******************************************************************************
+ * The MIT License
+ *
+ * Copyright (c) 2010 Perry Hung (from <libmaple/i2c.h>).
+ * Copyright (c) 2012 LeafLabs, LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *****************************************************************************/
+
+/**
+ * @file libmaple/include/libmaple/i2c_common.h
+ * @author Marti Bolivar <mbolivar@leaflabs.com>
+ * @brief This file is an implementation detail
+ *
+ * CONTENTS UNSTABLE. The existence of this file is an implementation
+ * detail.  Never include it directly.  If you need something from
+ * here, include <libmaple/i2c.h> instead.
+ *
+ * I2C slave support added 2012 by Barry Carter. barry.carter@gmail.com, headfuzz.co.uk
+ *
+ */
+
+#ifndef _LIBMAPLE_I2C_COMMON_H_
+#define _LIBMAPLE_I2C_COMMON_H_
+
+#include <libmaple/libmaple_types.h>
+#include <libmaple/nvic.h>
+#include <libmaple/rcc.h>
+
+struct gpio_dev;
+struct i2c_reg_map;
+struct i2c_msg;
+
+/** I2C device states */
+typedef enum i2c_state {
+    I2C_STATE_DISABLED          = 0, /**< Disabled */
+    I2C_STATE_IDLE              = 1, /**< Idle */
+    I2C_STATE_XFER_DONE         = 2, /**< Done with transfer */
+    I2C_STATE_BUSY              = 3, /**< Busy */
+    I2C_STATE_SL_RX             = 4, /**< Slave receiving */
+    I2C_STATE_ERROR             = -1 /**< Error occurred */
+} i2c_state;
+
+typedef void (*i2c_slave_recv_callback_func)(struct i2c_msg *);
+typedef void (*i2c_slave_transmit_callback_func)(struct i2c_msg *);
+/**
+ * @brief I2C device type.
+ */
+typedef struct i2c_dev {
+    struct i2c_reg_map *regs;   /**< Register map */
+    struct i2c_msg *msg;        /**< Messages */
+    uint32 error_flags;         /**< Error flags, set on I2C error condition */
+    volatile uint32 timestamp;  /**< For internal use */
+
+    /**
+     * @brief Deprecated. Use .scl_port or .sda_port instead.
+     * If non-null, this will be used as SDA, SCL pins' GPIO port. If
+     * null, then .sda_port will be used for SDA, and .sda_port for
+     * SDA. */
+    struct gpio_dev *gpio_port;
+
+    /**
+     * @brief SDA GPIO device (but see .gpio_port).
+     */
+    struct gpio_dev *sda_port;
+
+    /**
+     * @brief SCL GPIO device (but see .gpio_port).
+     */
+    struct gpio_dev *scl_port;
+
+    uint16 msgs_left;           /**< Messages left */
+    uint8 sda_pin;              /**< SDA bit on gpio_port */
+    uint8 scl_pin;              /**< SCL bit on gpio_port */
+    rcc_clk_id clk_id;          /**< RCC clock information */
+    nvic_irq_num ev_nvic_line;  /**< Event IRQ number */
+    nvic_irq_num er_nvic_line;  /**< Error IRQ number */
+    volatile i2c_state state;   /**< Device state */
+    uint32 config_flags;        /**< Configuration flags */
+
+    /*
+     * Slave implementation. Callback functions in this struct allow
+     * for a separate callback function for each I2C unit available onboard
+     */
+    i2c_slave_transmit_callback_func i2c_slave_transmit_callback;
+    i2c_slave_recv_callback_func i2c_slave_recv_callback;
+
+    struct i2c_msg *i2c_slave_msg; /* the message that the i2c slave will use */
+
+} i2c_dev;
+
+#endif

STM32F1/libraries/WireSlave/src/libmaple/i2c_slave.h

@@ -0,0 +1,475 @@
+/******************************************************************************
+ * The MIT License
+ *
+ * Copyright (c) 2010 Perry Hung.
+ * Copyright (c) 2012 LeafLabs, LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *****************************************************************************/
+
+/**
+ * @file libmaple/include/libmaple/i2c.h
+ * @brief Inter-Integrated Circuit (I2C) peripheral support
+ *
+ * Supports Master and Slave.
+ *  Master Usage notes:
+ *
+ * - Enable an I2C device with i2c_master_enable().
+ * - Initialize an array of struct i2c_msg to suit the bus
+ *   transactions (reads/writes) you wish to perform.
+ * - Call i2c_master_xfer() to do the work.
+ *
+ * Slave Usage notes:
+ * - Enable I2C slave by calling i2c_slave_enable().
+ *   Check flags for usage. Enabling master also enabled slave.
+ * - initialise the i2c_msg struct and the data buffer
+ * - initialise the callback functions
+ *
+ * I2C slave support added 2012 by Barry Carter. barry.carter@gmail.com, headfuzz.co.uk
+ */
+
+#ifndef _LIBMAPLE_I2C_H_
+#define _LIBMAPLE_I2C_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * Series header must provide:
+ *
+ * - uint32 _i2c_bus_clk(i2c_dev*): Clock frequency of dev's bus, in
+ *   MHz. (This is for internal use only).
+ *
+ * - (optional) _I2C_HAVE_IRQ_FIXUP: Leave undefined, or define to 1.
+ *   This is for internal use only. It's a hack to work around a
+ *   silicon bug related to I2C IRQ pre-emption on some targets. If 1,
+ *   the series header must also declare and implement a routine with
+ *   this signature (it may also be provided as a macro):
+ *
+ *       void _i2c_irq_priority_fixup(i2c_dev*)
+ *
+ *   This will be called by i2c_enable_irq() before actually enabling
+ *   I2C interrupts.
+ *
+ * - Reg. map base pointers, device pointer declarations.
+ */
+
+ /* Roger clark. Replaced with line below #include <series/i2c.h>*/
+#include "libmaple/i2c_common_slave.h"
+#include "stm32f1/include/series/i2c.h"
+
+#include <libmaple/libmaple_types.h>
+#include <libmaple/rcc.h>
+#include <libmaple/nvic.h>
+#include <libmaple/gpio.h>
+
+/** I2C register map type */
+typedef struct i2c_reg_map {
+    __io uint32 CR1;            /**< Control register 1 */
+    __io uint32 CR2;            /**< Control register 2 */
+    __io uint32 OAR1;           /**< Own address register 1 */
+    __io uint32 OAR2;           /**< Own address register 2 */
+    __io uint32 DR;             /**< Data register */
+    __io uint32 SR1;            /**< Status register 1 */
+    __io uint32 SR2;            /**< Status register 2 */
+    __io uint32 CCR;            /**< Clock control register */
+    __io uint32 TRISE;          /**< TRISE (rise time) register */
+} i2c_reg_map;
+
+/**
+ * @brief I2C message type
+ */
+typedef struct i2c_msg {
+    uint16 addr;                /**< Address */
+
+#define I2C_MSG_READ            0x1
+#define I2C_MSG_10BIT_ADDR      0x2
+    /**
+     * Bitwise OR of:
+     * - I2C_MSG_READ (write is default)
+     * - I2C_MSG_10BIT_ADDR (7-bit is default) */
+    uint16 flags;
+
+    uint16 length;              /**< Message length */
+    uint16 xferred;             /**< Messages transferred */
+    uint8 *data;                /**< Data */
+} i2c_msg;
+
+/*
+ * Register bit definitions
+ */
+
+/* Control register 1 */
+
+#define I2C_CR1_SWRST           (1U << 15)    // Software reset
+#define I2C_CR1_ALERT           (1U << 13)    // SMBus alert
+#define I2C_CR1_PEC             (1U << 12)    // Packet error checking
+#define I2C_CR1_POS             (1U << 11)    // Acknowledge/PEC position
+#define I2C_CR1_ACK             (1U << 10)    // Acknowledge enable
+#define I2C_CR1_STOP            (1U << 9)     // Stop generation
+#define I2C_CR1_START           (1U << 8)     // Start generation
+#define I2C_CR1_NOSTRETCH       (1U << 7)     // Clock stretching disable
+#define I2C_CR1_ENGC            (1U << 6)     // General call enable
+#define I2C_CR1_ENPEC           (1U << 5)     // PEC enable
+#define I2C_CR1_ENARP           (1U << 4)     // ARP enable
+#define I2C_CR1_SMBTYPE         (1U << 3)     // SMBus type
+#define I2C_CR1_SMBTYPE_DEVICE  (0U << 3)     //     SMBus type: device
+#define I2C_CR1_SMBTYPE_HOST    (1U << 3)     //     SMBus type: host
+#define I2C_CR1_SMBUS           (1U << 1)     // SMBus mode
+#define I2C_CR1_SMBUS_I2C       (0U << 1)     //     SMBus mode: I2C
+#define I2C_CR1_SMBUS_SMBUS     (1U << 1)     //     SMBus mode: SMBus
+#define I2C_CR1_PE              (1U << 0)     // Peripheral Enable
+
+/* Control register 2 */
+
+#define I2C_CR2_LAST            (1U << 12)    // DMA last transfer
+#define I2C_CR2_DMAEN           (1U << 11)    // DMA requests enable
+#define I2C_CR2_ITBUFEN         (1U << 10)    // Buffer interrupt enable
+#define I2C_CR2_ITEVTEN         (1U << 9)     // Event interupt enable
+#define I2C_CR2_ITERREN         (1U << 8)     // Error interupt enable
+#define I2C_CR2_FREQ            0x3F          // Peripheral input frequency
+
+/* Own address register 1 */
+
+#define I2C_OAR1_ADDMODE        (1U << 15)    // Addressing mode
+#define I2C_OAR1_ADDMODE_7_BIT  (0U << 15)    //     Addressing mode: 7-bit
+#define I2C_OAR1_ADDMODE_10_BIT (1U << 15)    //     Addressing mode: 10-bit
+#define I2C_OAR1_ADD            0x3FF         // Interface address
+
+/* Own address register 2 */
+
+#define I2C_OAR2_ADD2           0xFE          // Interface address
+#define I2C_OAR2_ENDUAL         1U            // Dual addressing mode enable
+
+/* Status register 1 */
+
+#define I2C_SR1_SMBALERT        (1U << 15)    // SMBus alert
+#define I2C_SR1_TIMEOUT         (1U << 14)    // Timeout or Tlow error
+#define I2C_SR1_PECERR          (1U << 12)    // PEC Error in reception
+#define I2C_SR1_OVR             (1U << 11)    // Overrun/underrun
+#define I2C_SR1_AF              (1U << 10)    // Acknowledge failure
+#define I2C_SR1_ARLO            (1U << 9)     // Arbitration lost
+#define I2C_SR1_BERR            (1U << 8)     // Bus error
+#define I2C_SR1_TXE             (1U << 7)     // Data register empty
+#define I2C_SR1_RXNE            (1U << 6)     // Data register not empty
+#define I2C_SR1_STOPF           (1U << 4)     // Stop detection
+#define I2C_SR1_ADD10           (1U << 3)     // 10-bit header sent
+#define I2C_SR1_BTF             (1U << 2)     // Byte transfer finished
+#define I2C_SR1_ADDR            (1U << 1)     // Address sent/matched
+#define I2C_SR1_SB              (1U << 0)     // Start bit
+
+/* Status register 2 */
+
+#define I2C_SR2_PEC             0xFF00        // Packet error checking register
+#define I2C_SR2_DUALF           (1U << 7)     // Dual flag
+#define I2C_SR2_SMBHOST         (1U << 6)     // SMBus host header
+#define I2C_SR2_SMBDEFAULT      (1U << 5)     // SMBus device default address
+#define I2C_SR2_GENCALL         (1U << 4)     // General call address
+#define I2C_SR2_TRA             (1U << 2)     // Transmitter/receiver
+#define I2C_SR2_BUSY            (1U << 1)     // Bus busy
+#define I2C_SR2_MSL             (1U << 0)     // Master/slave
+
+/* Clock control register */
+
+#define I2C_CCR_FS              (1U << 15)    // Fast mode selection
+#define I2C_CCR_DUTY            (1U << 14)    // Fast mode duty cycle
+#define I2C_CCR_DUTY_2_1        (0U << 14)    //     Fast mode duty: 2/1
+#define I2C_CCR_DUTY_16_9       (1U << 14)    //     Fast mode duty: 16/9
+#define I2C_CCR_CCR             0xFFF         // Clock control bits
+
+/*
+ * Convenience routines
+ */
+
+/* Main I2C API */
+
+/* I2C enable options */
+#define I2C_FAST_MODE           0x1           // 400 khz
+#define I2C_DUTY_16_9           0x2           // 16/9 duty ratio
+/* Flag 0x4 is reserved; DO NOT USE. */
+#define I2C_BUS_RESET           0x8           // Perform a bus reset
+#define I2C_SLAVE_USE_RX_BUFFER 0x10          // Use a buffered message when doing a slave recv
+#define I2C_SLAVE_USE_TX_BUFFER 0x20          // Use a buffered message when doing a slave transmit
+#define I2C_SLAVE_DUAL_ADDRESS  0x40          // Enable the dual slave address scheme
+#define I2C_SLAVE_GENERAL_CALL  0x80          // Enable the general call on address 0x00
+void i2c_master_enable(i2c_dev *dev, uint32 flags);
+void i2c_slave_enable(i2c_dev *dev, uint32 flags);
+
+#define I2C_ERROR_PROTOCOL      (-1)
+#define I2C_ERROR_TIMEOUT       (-2)
+int32 i2c_master_xfer(i2c_dev *dev, i2c_msg *msgs, uint16 num, uint32 timeout);
+
+void i2c_bus_reset(const i2c_dev *dev);
+
+/**
+ * @brief Disable an I2C device
+ *
+ * This function disables the corresponding peripheral and marks dev's
+ * state as I2C_STATE_DISABLED.
+ *
+ * @param dev Device to disable.
+ */
+static inline void i2c_disable(i2c_dev *dev) {
+    dev->regs->CR1 &= ~I2C_CR1_PE;
+    dev->state = I2C_STATE_DISABLED;
+}
+
+/* Start/stop conditions */
+
+/**
+ * @brief Generate a start condition on the bus.
+ * @param dev I2C device
+ */
+static inline void i2c_start_condition(i2c_dev *dev) {
+    uint32 cr1;
+    while ((cr1 = dev->regs->CR1) & (I2C_CR1_START |
+                                     I2C_CR1_STOP  |
+                                     I2C_CR1_PEC)) {
+        ;
+    }
+    dev->regs->CR1 |= I2C_CR1_START;
+}
+
+/**
+ * @brief Generate a stop condition on the bus
+ * @param dev I2C device
+ */
+static inline void i2c_stop_condition(i2c_dev *dev) {
+    uint32 cr1;
+    while ((cr1 = dev->regs->CR1) & (I2C_CR1_START |
+                                     I2C_CR1_STOP  |
+                                     I2C_CR1_PEC)) {
+        ;
+    }
+    dev->regs->CR1 |= I2C_CR1_STOP;
+    while ((cr1 = dev->regs->CR1) & (I2C_CR1_START |
+                                     I2C_CR1_STOP  |
+                                     I2C_CR1_PEC)) {
+        ;
+    }
+
+}
+
+/* IRQ enable/disable */
+
+#ifndef _I2C_HAVE_IRQ_FIXUP
+/* The series header provides this if _I2C_HAVE_IRQ_FIXUP is defined,
+ * but we need it either way. */
+#define _i2c_irq_priority_fixup(dev) ((void)0)
+#endif
+
+#define I2C_IRQ_ERROR              I2C_CR2_ITERREN
+#define I2C_IRQ_EVENT              I2C_CR2_ITEVTEN
+#define I2C_IRQ_BUFFER             I2C_CR2_ITBUFEN
+/**
+ * @brief Enable one or more I2C interrupts
+ * @param dev I2C device
+ * @param irqs Bitwise or of:
+ *             I2C_IRQ_ERROR (error interrupt),
+ *             I2C_IRQ_EVENT (event interrupt), and
+ *             I2C_IRQ_BUFFER (buffer interrupt).
+ */
+static inline void i2c_enable_irq(i2c_dev *dev, uint32 irqs) {
+    _i2c_irq_priority_fixup(dev);
+    dev->regs->CR2 |= irqs;
+}
+
+/**
+ * @brief Disable one or more I2C interrupts
+ * @param dev I2C device
+ * @param irqs Bitwise or of:
+ *             I2C_IRQ_ERROR (error interrupt),
+ *             I2C_IRQ_EVENT (event interrupt), and
+ *             I2C_IRQ_BUFFER (buffer interrupt).
+ */
+static inline void i2c_disable_irq(i2c_dev *dev, uint32 irqs) {
+    dev->regs->CR2 &= ~irqs;
+}
+
+/* ACK/NACK */
+
+/**
+ * @brief Enable I2C acknowledgment
+ * @param dev I2C device
+ */
+static inline void i2c_enable_ack(i2c_dev *dev) {
+    dev->regs->CR1 |= I2C_CR1_ACK;
+}
+
+/**
+ * @brief Disable I2C acknowledgment
+ * @param dev I2C device
+ */
+static inline void i2c_disable_ack(i2c_dev *dev) {
+    dev->regs->CR1 &= ~I2C_CR1_ACK;
+}
+
+/* GPIO control */
+
+/**
+ * @brief Configure device GPIOs.
+ *
+ * Configure GPIO bits dev->sda_pin and dev->scl_pin on GPIO device
+ * dev->gpio_port for use with I2C device dev.
+ *
+ * @param dev I2C Device
+ * @see i2c_release_gpios()
+ */
+extern void i2c_config_gpios(const i2c_dev *dev);
+
+/**
+ * @brief Release GPIOs controlling an I2C bus
+ *
+ * Releases the I2C bus controlled by dev as master, and disconnects
+ * GPIO bits dev->sda_pin and dev->scl_pin on GPIO device
+ * dev->gpio_port from I2C device dev.
+ *
+ * @param dev I2C device
+ * @see i2c_config_gpios()
+ */
+extern void i2c_master_release_bus(const i2c_dev *dev);
+
+/* Miscellaneous low-level routines */
+
+void i2c_init(i2c_dev *dev);
+
+/**
+ * @brief Turn on an I2C peripheral
+ * @param dev Device to enable
+ */
+static inline void i2c_peripheral_enable(i2c_dev *dev) {
+    dev->regs->CR1 |= I2C_CR1_PE;
+}
+
+/**
+ * @brief Turn off an I2C peripheral
+ * @param dev Device to turn off
+ */
+static inline void i2c_peripheral_disable(i2c_dev *dev) {
+    dev->regs->CR1 &= ~I2C_CR1_PE;
+}
+
+/**
+ * @brief Fill transmit register
+ * @param dev I2C device
+ * @param byte Byte to write
+ */
+static inline void i2c_write(i2c_dev *dev, uint8 byte) {
+    dev->regs->DR = byte;
+}
+
+/**
+ * @brief Set input clock frequency, in MHz
+ * @param dev I2C device
+ * @param freq Frequency, in MHz. This must be at least 2, and at most
+ *             the APB frequency of dev's bus. (For example, if
+ *             rcc_dev_clk(dev) == RCC_APB1, freq must be at most
+ *             PCLK1, in MHz). There is an additional limit of 46 MHz.
+ */
+static inline void i2c_set_input_clk(i2c_dev *dev, uint32 freq) {
+#define I2C_MAX_FREQ_MHZ 46
+    ASSERT(2 <= freq && freq <= _i2c_bus_clk(dev) && freq <= I2C_MAX_FREQ_MHZ);
+    uint32 cr2 = dev->regs->CR2;
+    cr2 &= ~I2C_CR2_FREQ;
+    cr2 |= freq;
+    dev->regs->CR2 = freq;
+#undef I2C_MAX_FREQ_MHZ
+}
+
+/**
+ * @brief Set I2C clock control register.
+ *
+ * See the chip reference manual for the details.
+ *
+ * @param dev I2C device
+ * @param val Value to use for clock control register (in
+ *            Fast/Standard mode)
+ */
+static inline void i2c_set_clk_control(i2c_dev *dev, uint32 val) {
+    uint32 ccr = dev->regs->CCR;
+    ccr &= ~I2C_CCR_CCR;
+    ccr |= val;
+    dev->regs->CCR = ccr;
+}
+
+/**
+ * @brief Set SCL rise time
+ * @param dev I2C device
+ * @param trise Maximum rise time in fast/standard mode (see chip
+ *              reference manual for the relevant formulas).
+ */
+static inline void i2c_set_trise(i2c_dev *dev, uint32 trise) {
+    dev->regs->TRISE = trise;
+}
+
+/*
+ * Slave support
+ */
+
+/**
+ * @brief Enable Dual addressing mode to allow peripheral to have 2 addresses
+ * @param dev I2C device
+  */
+static inline void i2c_slave_dual_address_enable(i2c_dev *dev) {
+    dev->regs->OAR2 |= I2C_OAR2_ENDUAL;
+}
+
+/**
+ * @brief Enable General Call to allow the  unit to respond on addr 0x00
+ * @param dev I2C device
+  */
+static inline void i2c_slave_general_call_enable(i2c_dev *dev) {
+    dev->regs->CR1 |= I2C_CR1_ENGC;
+}
+
+/* callback functions */
+/* Callback handler for data received over the bus */
+void i2c_slave_attach_recv_handler(i2c_dev *dev, i2c_msg *msg, i2c_slave_recv_callback_func func);
+
+/* Callback handler for data being requested over the bus
+ * The callback function must call i2c_write to get the data over the bus
+ */
+void i2c_slave_attach_transmit_handler(i2c_dev *dev, i2c_msg *msg, i2c_slave_transmit_callback_func func);
+
+/**
+ * @brief Set the primary I2c slave address
+ * @param dev I2C device
+ * @param address the 8 or 10 bit i2c address
+  */
+static inline void i2c_slave_set_own_address(i2c_dev *dev, uint16 address) {
+    dev->regs->OAR1 = address <<1;
+}
+
+/**
+ * @brief Set the secondary I2c slave address
+ * @param dev I2C device
+ * @param address the 8 or 10 bit i2c address
+  */
+static inline void i2c_slave_set_own_address2(i2c_dev *dev, uint16 address) {
+dev->regs->OAR2 = (address <<1 ) | I2C_OAR2_ENDUAL;
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

STM32F1/libraries/WireSlave/src/utility/WireBase_slave.cpp

@@ -0,0 +1,145 @@
+/******************************************************************************
+ * The MIT License
+ *
+ * Copyright (c) 2010 LeafLabs LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *****************************************************************************/
+
+/**
+ * @file WireBase.cpp
+ * @author Trystan Jones <crenn6977@gmail.com>
+ * @brief Wire library, following the majority of the interface from Arduino.
+ *        Provides a 'standard' interface to I2C (two-wire) communication for
+ *        derived classes.
+ */
+
+/*
+ * Library created by crenn to allow a system which would provide users the
+ * 'standardised' Arduino method for interfacing with I2C devices regardless of
+ * whether it is I2C hardware or emulating software.
+ */
+
+#include "WireBase_slave.h"
+#include "wirish.h"
+
+void WireBase::begin(uint8 self_addr) {
+    tx_buf_idx = 0;
+    tx_buf_overflow = false;
+    rx_buf_idx = 0;
+    rx_buf_len = 0;
+}
+
+void WireBase::beginTransmission(uint8 slave_address) {
+    itc_msg.addr = slave_address;
+    itc_msg.data = &tx_buf[tx_buf_idx];
+    itc_msg.length = 0;
+    itc_msg.flags = 0;
+}
+
+void WireBase::beginTransmission(int slave_address) {
+    beginTransmission((uint8)slave_address);
+}
+
+uint8 WireBase::endTransmission(bool stop) {
+    uint8 retVal;
+    if (tx_buf_overflow) {
+        return EDATA;
+    }
+    retVal = process(stop);// Changed so that the return value from process is returned by this function see also the return line below
+    tx_buf_idx = 0;
+    tx_buf_overflow = false;
+    return retVal;//SUCCESS;
+}
+
+uint8 WireBase::endTransmission(){
+    endTransmission(true);
+}
+
+//TODO: Add the ability to queue messages (adding a boolean to end of function
+// call, allows for the Arduino style to stay while also giving the flexibility
+// to bulk send
+uint8 WireBase::requestFrom(uint8 address, int num_bytes) {
+    if (num_bytes > BUFFER_LENGTH) {
+        num_bytes = BUFFER_LENGTH;
+    }
+    itc_msg.addr = address;
+    itc_msg.flags = I2C_MSG_READ;
+    itc_msg.length = num_bytes;
+    itc_msg.data = &rx_buf[rx_buf_idx];
+    process();
+    rx_buf_len += itc_msg.xferred;
+    itc_msg.flags = 0;
+    return rx_buf_len;
+}
+
+uint8 WireBase::requestFrom(int address, int numBytes) {
+    return WireBase::requestFrom((uint8)address, numBytes);
+}
+
+void WireBase::write(uint8 value) {
+    if (tx_buf_idx == BUFFER_LENGTH) {
+        tx_buf_overflow = true;
+        return;
+    }
+    tx_buf[tx_buf_idx++] = value;
+    itc_msg.length++;
+}
+
+void WireBase::write(uint8* buf, int len) {
+    for (uint8 i = 0; i < len; i++) {
+        write(buf[i]);
+    }
+}
+
+void WireBase::write(int value) {
+    write((uint8)value);
+}
+
+void WireBase::write(int* buf, int len) {
+    write((uint8*)buf, (uint8)len);
+}
+
+void WireBase::write(char* buf) {
+    uint8 *ptr = (uint8*)buf;
+    while (*ptr) {
+        write(*ptr);
+        ptr++;
+    }
+}
+
+uint8 WireBase::available() {
+    return rx_buf_len - rx_buf_idx;
+}
+
+uint8 WireBase::read() {
+    if (rx_buf_idx == rx_buf_len) {
+        rx_buf_idx = 0;
+        rx_buf_len = 0;
+        return 0;
+    } else if (rx_buf_idx == (rx_buf_len-1)) {
+        uint8 temp = rx_buf[rx_buf_idx];
+        rx_buf_idx = 0;
+        rx_buf_len = 0;
+        return temp;
+    }
+    return rx_buf[rx_buf_idx++];
+}

STM32F1/libraries/WireSlave/src/utility/WireBase_slave.h

@@ -0,0 +1,145 @@
+/******************************************************************************
+ * The MIT License
+ *
+ * Copyright (c) 2010 LeafLabs LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *****************************************************************************/
+
+/**
+ * @file WireBase.h
+ * @author Trystan Jones <crenn6977@gmail.com>
+ * @brief Wire library, following the majority of the interface from Arduino.
+ *        Provides a 'standard' interface to I2C (two-wire) communication for
+ *        derived classes.
+ */
+
+/*
+ * Library created by crenn to allow a system which would provide users the
+ * 'standardised' Arduino method for interfacing with I2C devices regardless of
+ * whether it is I2C hardware or emulating software.
+ */
+
+#ifndef _WIREBASE_H_
+#define _WIREBASE_H_
+
+#include "wirish.h"
+#include <libmaple/i2c_slave.h>
+
+#define BUFFER_LENGTH 32
+
+/* return codes from endTransmission() */
+#define SUCCESS   0        /* transmission was successful */
+#define EDATA     1        /* too much data */
+#define ENACKADDR 2        /* received nack on transmit of address */
+#define ENACKTRNS 3        /* received nack on transmit of data */
+#define EOTHER    4        /* other error */
+
+class WireBase { // Abstraction is awesome!
+protected:
+    i2c_msg itc_msg;
+    uint8 rx_buf[BUFFER_LENGTH];      /* receive buffer */
+    uint8 rx_buf_idx;               /* first unread idx in rx_buf */
+    uint8 rx_buf_len;               /* number of bytes read */
+
+    uint8 tx_buf[BUFFER_LENGTH];      /* transmit buffer */
+    uint8 tx_buf_idx;  // next idx available in tx_buf, -1 overflow
+    boolean tx_buf_overflow;
+
+    // Force derived classes to define process function
+    virtual uint8 process(uint8) = 0;
+    virtual uint8 process() = 0;
+public:
+    WireBase() {}
+    ~WireBase() {}
+
+    /*
+     * Initialises the class interface
+     */
+    // Allow derived classes to overwrite begin function
+    virtual void begin(uint8 = 0x00);
+
+    /*
+     * Sets up the transmission message to be processed
+     */
+    void beginTransmission(uint8);
+
+    /*
+     * Allow only 8 bit addresses to be used
+     */
+    void beginTransmission(int);
+
+    /*
+     * Call the process function to process the message if the TX
+     * buffer has not overflowed.
+     */
+    uint8 endTransmission(bool);
+    uint8 endTransmission(void);
+
+    /*
+     * Request bytes from a slave device and process the request,
+     * storing into the receiving buffer.
+     */
+    uint8 requestFrom(uint8, int);
+
+    /*
+     * Allow only 8 bit addresses to be used when requesting bytes
+     */
+    uint8 requestFrom(int, int);
+
+    /*
+     * Stack up bytes to be sent when transmitting
+     */
+    void write(uint8);
+
+    /*
+     * Stack up bytes from the array to be sent when transmitting
+     */
+    void write(uint8*, int);
+
+    /*
+     * Ensure that a sending data will only be 8-bit bytes
+     */
+    void write(int);
+
+    /*
+     * Ensure that an array sending data will only be 8-bit bytes
+     */
+    void write(int*, int);
+
+    /*
+     * Stack up bytes from a string to be sent when transmitting
+     */
+    void write(char*);
+
+    /*
+     * Return the amount of bytes that is currently in the receiving buffer
+     */
+    uint8 available();
+
+    /*
+     * Return the value of byte in the receiving buffer that is currently being
+     * pointed to
+     */
+    uint8 read();
+};
+
+#endif // _WIREBASE_H_