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SPI Transactions for AVR

This commit is contained in:
PaulStoffregen 2014-08-01 05:38:27 -07:00
parent e057236dd6
commit 48f5256789
2 changed files with 325 additions and 45 deletions
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104
libraries/SPI/SPI.cpp
View File

@ -1,5 +1,6 @@
/*
* Copyright (c) 2010 by Cristian Maglie <c.maglie@bug.st>
* Copyright (c) 2014 by Paul Stoffregen <paul@pjrc.com> (Transaction API)
* SPI Master library for arduino.
*
* This file is free software; you can redistribute it and/or modify
@ -8,13 +9,20 @@
* published by the Free Software Foundation.
*/
#include "pins_arduino.h"
#include "SPI.h"
#include "pins_arduino.h"
SPIClass SPI;
void SPIClass::begin() {
uint8_t SPIClass::interruptMode = 0;
uint8_t SPIClass::interruptMask = 0;
uint8_t SPIClass::interruptSave = 0;
#ifdef SPI_TRANSACTION_MISMATCH_LED
uint8_t SPIClass::inTransactionFlag = 0;
#endif
void SPIClass::begin()
{
// Set SS to high so a connected chip will be "deselected" by default
digitalWrite(SS, HIGH);
@ -39,28 +47,86 @@ void SPIClass::begin() {
pinMode(MOSI, OUTPUT);
}
void SPIClass::end() {
SPCR &= ~_BV(SPE);
}
void SPIClass::setBitOrder(uint8_t bitOrder)
// mapping of interrupt numbers to bits within SPI_AVR_EIMSK
#if defined(__AVR_ATmega32U4__)
#define SPI_INT0_MASK (1<<INT0)
#define SPI_INT1_MASK (1<<INT1)
#define SPI_INT2_MASK (1<<INT2)
#define SPI_INT3_MASK (1<<INT3)
#define SPI_INT4_MASK (1<<INT6)
#elif defined(__AVR_AT90USB646__) || defined(__AVR_AT90USB1286__)
#define SPI_INT0_MASK (1<<INT0)
#define SPI_INT1_MASK (1<<INT1)
#define SPI_INT2_MASK (1<<INT2)
#define SPI_INT3_MASK (1<<INT3)
#define SPI_INT4_MASK (1<<INT4)
#define SPI_INT5_MASK (1<<INT5)
#define SPI_INT6_MASK (1<<INT6)
#define SPI_INT7_MASK (1<<INT7)
#elif defined(EICRA) && defined(EICRB) && defined(EIMSK)
#define SPI_INT0_MASK (1<<INT4)
#define SPI_INT1_MASK (1<<INT5)
#define SPI_INT2_MASK (1<<INT0)
#define SPI_INT3_MASK (1<<INT1)
#define SPI_INT4_MASK (1<<INT2)
#define SPI_INT5_MASK (1<<INT3)
#define SPI_INT6_MASK (1<<INT6)
#define SPI_INT7_MASK (1<<INT7)
#else
#ifdef INT0
#define SPI_INT0_MASK (1<<INT0)
#endif
#ifdef INT1
#define SPI_INT1_MASK (1<<INT1)
#endif
#ifdef INT2
#define SPI_INT2_MASK (1<<INT2)
#endif
#endif
void SPIClass::usingInterrupt(uint8_t interruptNumber)
{
if(bitOrder == LSBFIRST) {
SPCR |= _BV(DORD);
} else {
SPCR &= ~(_BV(DORD));
uint8_t mask;
if (interruptMode > 1) return;
noInterrupts();
switch (interruptNumber) {
#ifdef SPI_INT0_MASK
case 0: mask = SPI_INT0_MASK; break;
#endif
#ifdef SPI_INT1_MASK
case 1: mask = SPI_INT1_MASK; break;
#endif
#ifdef SPI_INT2_MASK
case 2: mask = SPI_INT2_MASK; break;
#endif
#ifdef SPI_INT3_MASK
case 3: mask = SPI_INT3_MASK; break;
#endif
#ifdef SPI_INT4_MASK
case 4: mask = SPI_INT4_MASK; break;
#endif
#ifdef SPI_INT5_MASK
case 5: mask = SPI_INT5_MASK; break;
#endif
#ifdef SPI_INT6_MASK
case 6: mask = SPI_INT6_MASK; break;
#endif
#ifdef SPI_INT7_MASK
case 7: mask = SPI_INT7_MASK; break;
#endif
default:
interruptMode = 2;
interrupts();
return;
}
}
void SPIClass::setDataMode(uint8_t mode)
{
SPCR = (SPCR & ~SPI_MODE_MASK) | mode;
}
void SPIClass::setClockDivider(uint8_t rate)
{
SPCR = (SPCR & ~SPI_CLOCK_MASK) | (rate & SPI_CLOCK_MASK);
SPSR = (SPSR & ~SPI_2XCLOCK_MASK) | ((rate >> 2) & SPI_2XCLOCK_MASK);
interruptMode = 1;
interruptMask |= mask;
interrupts();
}

266
libraries/SPI/SPI.h
View File

@ -1,5 +1,7 @@
/*
* Copyright (c) 2010 by Cristian Maglie <c.maglie@bug.st>
* Copyright (c) 2014 by Paul Stoffregen <paul@pjrc.com> (Transaction API)
* Copyright (c) 2014 by Matthijs Kooijman <matthijs@stdin.nl> (SPISettings AVR)
* SPI Master library for arduino.
*
* This file is free software; you can redistribute it and/or modify
@ -11,9 +13,24 @@
#ifndef _SPI_H_INCLUDED
#define _SPI_H_INCLUDED
#include <stdio.h>
#include <Arduino.h>
#include <avr/pgmspace.h>
// SPI_HAS_TRANSACTION means SPI has beginTransaction(), endTransaction(),
// usingInterrupt(), and SPISetting(clock, bitOrder, dataMode)
#define SPI_HAS_TRANSACTION 1
// Uncomment this line to add detection of mismatched begin/end transactions.
// A mismatch occurs if other libraries fail to use SPI.endTransaction() for
// each SPI.beginTransaction(). Connect a LED to this pin. The LED will turn
// on if any mismatch is ever detected.
//#define SPI_TRANSACTION_MISMATCH_LED 5
#ifndef LSBFIRST
#define LSBFIRST 0
#endif
#ifndef MSBFIRST
#define MSBFIRST 1
#endif
#define SPI_CLOCK_DIV4 0x00
#define SPI_CLOCK_DIV16 0x01
@ -22,7 +39,6 @@
#define SPI_CLOCK_DIV2 0x04
#define SPI_CLOCK_DIV8 0x05
#define SPI_CLOCK_DIV32 0x06
//#define SPI_CLOCK_DIV64 0x07
#define SPI_MODE0 0x00
#define SPI_MODE1 0x04
@ -33,38 +49,236 @@
#define SPI_CLOCK_MASK 0x03 // SPR1 = bit 1, SPR0 = bit 0 on SPCR
#define SPI_2XCLOCK_MASK 0x01 // SPI2X = bit 0 on SPSR
// define SPI_AVR_EIMSK for AVR boards with external interrupt pins
#if defined(EIMSK)
#define SPI_AVR_EIMSK EIMSK
#elif defined(GICR)
#define SPI_AVR_EIMSK GICR
#elif defined(GIMSK)
#define SPI_AVR_EIMSK GIMSK
#endif
class SPISettings {
public:
SPISettings(uint32_t clock, uint8_t bitOrder, uint8_t dataMode) {
if (__builtin_constant_p(clock)) {
init_AlwaysInline(clock, bitOrder, dataMode);
} else {
init_MightInline(clock, bitOrder, dataMode);
}
}
SPISettings() {
init_AlwaysInline(4000000, MSBFIRST, SPI_MODE0);
}
private:
void init_MightInline(uint32_t clock, uint8_t bitOrder, uint8_t dataMode) {
init_AlwaysInline(clock, bitOrder, dataMode);
}
void init_AlwaysInline(uint32_t clock, uint8_t bitOrder, uint8_t dataMode)
__attribute__((__always_inline__)) {
// Clock settings are defined as follows. Note that this shows SPI2X
// inverted, so the bits form increasing numbers. Also note that
// fosc/64 appears twice
// SPR1 SPR0 ~SPI2X Freq
// 0 0 0 fosc/2
// 0 0 1 fosc/4
// 0 1 0 fosc/8
// 0 1 1 fosc/16
// 1 0 0 fosc/32
// 1 0 1 fosc/64
// 1 1 0 fosc/64
// 1 1 1 fosc/128
// We find the fastest clock that is less than or equal to the
// given clock rate. The clock divider that results in clock_setting
// is 2 ^^ (clock_div + 1). If nothing is slow enough, we'll use the
// slowest (128 == 2 ^^ 7, so clock_div = 6).
uint8_t clockDiv;
// When the clock is known at compiletime, use this if-then-else
// cascade, which the compiler knows how to completely optimize
// away. When clock is not known, use a loop instead, which generates
// shorter code.
if (__builtin_constant_p(clock)) {
if (clock >= F_CPU / 2) {
clockDiv = 0;
} else if (clock >= F_CPU / 4) {
clockDiv = 1;
} else if (clock >= F_CPU / 8) {
clockDiv = 2;
} else if (clock >= F_CPU / 16) {
clockDiv = 3;
} else if (clock >= F_CPU / 32) {
clockDiv = 4;
} else if (clock >= F_CPU / 64) {
clockDiv = 5;
} else {
clockDiv = 6;
}
} else {
uint32_t clockSetting = F_CPU / 2;
clockDiv = 0;
while (clockDiv < 6 && clock < clockSetting) {
clockSetting /= 2;
clockDiv++;
}
}
// Compensate for the duplicate fosc/64
if (clockDiv == 6)
clockDiv = 7;
// Invert the SPI2X bit
clockDiv ^= 0x1;
// Pack into the SPISettings class
spcr = _BV(SPE) | _BV(MSTR) | ((bitOrder == LSBFIRST) ? _BV(DORD) : 0) |
(dataMode & SPI_MODE_MASK) | ((clockDiv >> 1) & SPI_CLOCK_MASK);
spsr = clockDiv & SPI_2XCLOCK_MASK;
}
uint8_t spcr;
uint8_t spsr;
friend class SPIClass;
};
class SPIClass {
public:
inline static byte transfer(byte _data);
// Initialize the SPI library
static void begin();
// SPI Configuration methods
// If SPI is to used from within an interrupt, this function registers
// that interrupt with the SPI library, so beginTransaction() can
// prevent conflicts. The input interruptNumber is the number used
// with attachInterrupt. If SPI is used from a different interrupt
// (eg, a timer), interruptNumber should be 255.
static void usingInterrupt(uint8_t interruptNumber);
inline static void attachInterrupt();
inline static void detachInterrupt(); // Default
// Before using SPI.transfer() or asserting chip select pins,
// this function is used to gain exclusive access to the SPI bus
// and configure the correct settings.
inline static void beginTransaction(SPISettings settings) {
if (interruptMode > 0) {
#ifdef SPI_AVR_EIMSK
if (interruptMode == 1) {
interruptSave = SPI_AVR_EIMSK;
SPI_AVR_EIMSK &= ~interruptMask;
} else
#endif
{
interruptSave = SREG;
cli();
}
}
#ifdef SPI_TRANSACTION_MISMATCH_LED
if (inTransactionFlag) {
pinMode(SPI_TRANSACTION_MISMATCH_LED, OUTPUT);
digitalWrite(SPI_TRANSACTION_MISMATCH_LED, HIGH);
}
inTransactionFlag = 1;
#endif
SPCR = settings.spcr;
SPSR = settings.spsr;
}
static void begin(); // Default
// Write to the SPI bus (MOSI pin) and also receive (MISO pin)
inline static uint8_t transfer(uint8_t data) {
SPDR = data;
asm volatile("nop");
while (!(SPSR & _BV(SPIF))) ; // wait
return SPDR;
}
inline static uint16_t transfer16(uint16_t data) {
union { uint16_t val; struct { uint8_t lsb; uint8_t msb; }; } in, out;
in.val = data;
if (!(SPCR & _BV(DORD))) {
SPDR = in.msb;
while (!(SPSR & _BV(SPIF))) ;
out.msb = SPDR;
SPDR = in.lsb;
while (!(SPSR & _BV(SPIF))) ;
out.lsb = SPDR;
} else {
SPDR = in.lsb;
while (!(SPSR & _BV(SPIF))) ;
out.lsb = SPDR;
SPDR = in.msb;
while (!(SPSR & _BV(SPIF))) ;
out.msb = SPDR;
}
return out.val;
}
inline static void transfer(void *buf, size_t count) {
if (count == 0) return;
uint8_t *p = (uint8_t *)buf;
SPDR = *p;
while (--count > 0) {
uint8_t out = *(p + 1);
while (!(SPSR & _BV(SPIF))) ;
uint8_t in = SPDR;
SPDR = out;
*p++ = in;
}
while (!(SPSR & _BV(SPIF))) ;
*p = SPDR;
}
// After performing a group of transfers and releasing the chip select
// signal, this function allows others to access the SPI bus
inline static void endTransaction(void) {
#ifdef SPI_TRANSACTION_MISMATCH_LED
if (!inTransactionFlag) {
pinMode(SPI_TRANSACTION_MISMATCH_LED, OUTPUT);
digitalWrite(SPI_TRANSACTION_MISMATCH_LED, HIGH);
}
inTransactionFlag = 0;
#endif
if (interruptMode > 0) {
#ifdef SPI_AVR_EIMSK
if (interruptMode == 1) {
SPI_AVR_EIMSK = interruptSave;
} else
#endif
{
SREG = interruptSave;
}
}
}
// Disable the SPI bus
static void end();
static void setBitOrder(uint8_t);
static void setDataMode(uint8_t);
static void setClockDivider(uint8_t);
// This function is deprecated. New applications should use
// beginTransaction() to configure SPI settings.
inline static void setBitOrder(uint8_t bitOrder) {
if (bitOrder == LSBFIRST) SPCR |= _BV(DORD);
else SPCR &= ~(_BV(DORD));
}
// This function is deprecated. New applications should use
// beginTransaction() to configure SPI settings.
inline static void setDataMode(uint8_t dataMode) {
SPCR = (SPCR & ~SPI_MODE_MASK) | dataMode;
}
// This function is deprecated. New applications should use
// beginTransaction() to configure SPI settings.
inline static void setClockDivider(uint8_t clockDiv) {
SPCR = (SPCR & ~SPI_CLOCK_MASK) | (clockDiv & SPI_CLOCK_MASK);
SPSR = (SPSR & ~SPI_2XCLOCK_MASK) | ((clockDiv >> 2) & SPI_2XCLOCK_MASK);
}
// These undocumented functions should not be used. SPI.transfer()
// polls the hardware flag which is automatically cleared as the
// AVR responds to SPI's interrupt
inline static void attachInterrupt() { SPCR |= _BV(SPIE); }
inline static void detachInterrupt() { SPCR &= ~_BV(SPIE); }
private:
static uint8_t interruptMode; // 0=none, 1=mask, 2=global
static uint8_t interruptMask; // which interrupts to mask
static uint8_t interruptSave; // temp storage, to restore state
#ifdef SPI_TRANSACTION_MISMATCH_LED
static uint8_t inTransactionFlag;
#endif
};
extern SPIClass SPI;
byte SPIClass::transfer(byte _data) {
SPDR = _data;
while (!(SPSR & _BV(SPIF)))
;
return SPDR;
}
void SPIClass::attachInterrupt() {
SPCR |= _BV(SPIE);
}
void SPIClass::detachInterrupt() {
SPCR &= ~_BV(SPIE);
}
#endif