From 48f5256789369bd5a4d8d9b9a663982aea717c7d Mon Sep 17 00:00:00 2001 From: PaulStoffregen Date: Fri, 1 Aug 2014 05:38:27 -0700 Subject: [PATCH] SPI Transactions for AVR --- libraries/SPI/SPI.cpp | 104 ++++++++++++++--- libraries/SPI/SPI.h | 266 +++++++++++++++++++++++++++++++++++++----- 2 files changed, 325 insertions(+), 45 deletions(-) diff --git a/libraries/SPI/SPI.cpp b/libraries/SPI/SPI.cpp index 5e48073..9a7a400 100644 --- a/libraries/SPI/SPI.cpp +++ b/libraries/SPI/SPI.cpp @@ -1,5 +1,6 @@ /* * Copyright (c) 2010 by Cristian Maglie + * Copyright (c) 2014 by Paul Stoffregen (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< 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(); } diff --git a/libraries/SPI/SPI.h b/libraries/SPI/SPI.h index f647d5c..962100b 100644 --- a/libraries/SPI/SPI.h +++ b/libraries/SPI/SPI.h @@ -1,5 +1,7 @@ /* * Copyright (c) 2010 by Cristian Maglie + * Copyright (c) 2014 by Paul Stoffregen (Transaction API) + * Copyright (c) 2014 by Matthijs Kooijman (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 #include -#include + +// 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