/* * Copyright (c) 2010 by Cristian Maglie * Copyright (c) 2014 by Paul Stoffregen (Transaction API) * Copyright (c) 2014 by Matthijs Kooijman (SPISettings) * SPI Master library for arduino. * * This file is free software; you can redistribute it and/or modify * it under the terms of either the GNU General Public License version 2 * or the GNU Lesser General Public License version 2.1, both as * published by the Free Software Foundation. */ #ifndef _SPI_H_INCLUDED #define _SPI_H_INCLUDED #include // SPI_HAS_TRANSACTION means SPI has beginTransaction(), endTransaction(), // usingInterrupt(), and SPISetting(clock, bitOrder, dataMode) #define SPI_HAS_TRANSACTION 1 #ifndef LSBFIRST #define LSBFIRST 0 #endif #ifndef MSBFIRST #define MSBFIRST 1 #endif #define SPI_MODE0 0x00 #define SPI_MODE1 0x04 #define SPI_MODE2 0x08 #define SPI_MODE3 0x0C #define SPI_CLOCK_DIV4 0x00 #define SPI_CLOCK_DIV16 0x01 #define SPI_CLOCK_DIV64 0x02 #define SPI_CLOCK_DIV128 0x03 #define SPI_CLOCK_DIV2 0x04 #define SPI_CLOCK_DIV8 0x05 #define SPI_CLOCK_DIV32 0x06 #define SPI_MODE_MASK 0x0C // CPOL = bit 3, CPHA = bit 2 on SPCR #define SPI_CLOCK_MASK 0x03 // SPR1 = bit 1, SPR0 = bit 0 on SPCR #define SPI_2XCLOCK_MASK 0x01 // SPI2X = bit 0 on SPSR /**********************************************************/ /* 8 bit AVR-based boards */ /**********************************************************/ #if defined(__AVR__) // 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: // Initialize the SPI library static void begin(); // 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); // 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(); } } SPCR = settings.spcr; SPSR = settings.spsr; } // 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 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) { 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(); // 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 }; // mapping of interrupt numbers to bits within SPI_AVR_EIMSK #if defined(__AVR_ATmega32U4__) #define SPI_INT0_MASK (1<= F_BUS / 2) { t = SPI_CTAR_PBR(0) | SPI_CTAR_BR(0) | SPI_CTAR_DBR | SPI_CTAR_CSSCK(0); } else if (clock >= F_BUS / 3) { t = SPI_CTAR_PBR(1) | SPI_CTAR_BR(0) | SPI_CTAR_DBR | SPI_CTAR_CSSCK(0); } else if (clock >= F_BUS / 4) { t = SPI_CTAR_PBR(0) | SPI_CTAR_BR(0) | SPI_CTAR_CSSCK(0); } else if (clock >= F_BUS / 5) { t = SPI_CTAR_PBR(2) | SPI_CTAR_BR(0) | SPI_CTAR_DBR | SPI_CTAR_CSSCK(0); } else if (clock >= F_BUS / 6) { t = SPI_CTAR_PBR(1) | SPI_CTAR_BR(0) | SPI_CTAR_CSSCK(0); } else if (clock >= F_BUS / 8) { t = SPI_CTAR_PBR(0) | SPI_CTAR_BR(1) | SPI_CTAR_CSSCK(1); } else if (clock >= F_BUS / 10) { t = SPI_CTAR_PBR(2) | SPI_CTAR_BR(0) | SPI_CTAR_CSSCK(0); } else if (clock >= F_BUS / 12) { t = SPI_CTAR_PBR(1) | SPI_CTAR_BR(1) | SPI_CTAR_CSSCK(1); } else if (clock >= F_BUS / 16) { t = SPI_CTAR_PBR(0) | SPI_CTAR_BR(3) | SPI_CTAR_CSSCK(2); } else if (clock >= F_BUS / 20) { t = SPI_CTAR_PBR(2) | SPI_CTAR_BR(1) | SPI_CTAR_CSSCK(0); } else if (clock >= F_BUS / 24) { t = SPI_CTAR_PBR(1) | SPI_CTAR_BR(3) | SPI_CTAR_CSSCK(2); } else if (clock >= F_BUS / 32) { t = SPI_CTAR_PBR(0) | SPI_CTAR_BR(4) | SPI_CTAR_CSSCK(3); } else if (clock >= F_BUS / 40) { t = SPI_CTAR_PBR(2) | SPI_CTAR_BR(3) | SPI_CTAR_CSSCK(2); } else if (clock >= F_BUS / 56) { t = SPI_CTAR_PBR(3) | SPI_CTAR_BR(3) | SPI_CTAR_CSSCK(2); } else if (clock >= F_BUS / 64) { t = SPI_CTAR_PBR(0) | SPI_CTAR_BR(5) | SPI_CTAR_CSSCK(4); } else if (clock >= F_BUS / 96) { t = SPI_CTAR_PBR(1) | SPI_CTAR_BR(5) | SPI_CTAR_CSSCK(4); } else if (clock >= F_BUS / 128) { t = SPI_CTAR_PBR(0) | SPI_CTAR_BR(6) | SPI_CTAR_CSSCK(5); } else if (clock >= F_BUS / 192) { t = SPI_CTAR_PBR(1) | SPI_CTAR_BR(6) | SPI_CTAR_CSSCK(5); } else if (clock >= F_BUS / 256) { t = SPI_CTAR_PBR(0) | SPI_CTAR_BR(7) | SPI_CTAR_CSSCK(6); } else if (clock >= F_BUS / 384) { t = SPI_CTAR_PBR(1) | SPI_CTAR_BR(7) | SPI_CTAR_CSSCK(6); } else if (clock >= F_BUS / 512) { t = SPI_CTAR_PBR(0) | SPI_CTAR_BR(8) | SPI_CTAR_CSSCK(7); } else if (clock >= F_BUS / 640) { t = SPI_CTAR_PBR(2) | SPI_CTAR_BR(7) | SPI_CTAR_CSSCK(6); } else { /* F_BUS / 768 */ t = SPI_CTAR_PBR(1) | SPI_CTAR_BR(8) | SPI_CTAR_CSSCK(7); } } else { for (uint32_t i=0; i<23; i++) { t = ctar_clock_table[i]; if (clock >= F_BUS / ctar_div_table[i]) break; } } if (dataMode & 0x08) { c |= SPI_CTAR_CPOL; } if (dataMode & 0x04) { c |= SPI_CTAR_CPHA; t = (t & 0xFFFF0FFF) | ((t & 0xF000) >> 4); } ctar = c | t; } static const uint16_t ctar_div_table[23]; static const uint32_t ctar_clock_table[23]; uint32_t ctar; friend class SPIClass; }; class SPIClass { public: // Initialize the SPI library static void begin(); // 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); static void usingInterrupt(IRQ_NUMBER_t interruptName); // 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(); } } if (SPI0_CTAR0 != settings.ctar) { SPI0_MCR = SPI_MCR_MDIS | SPI_MCR_HALT | SPI_MCR_PCSIS(0x1F); SPI0_CTAR0 = settings.ctar; SPI0_CTAR1 = settings.ctar| SPI_CTAR_FMSZ(8); SPI0_MCR = SPI_MCR_MSTR | SPI_MCR_PCSIS(0x1F); } } // 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 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) { 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(); // This function is deprecated. New applications should use // beginTransaction() to configure SPI settings. static void setBitOrder(uint8_t bitOrder); // This function is deprecated. New applications should use // beginTransaction() to configure SPI settings. static void setDataMode(uint8_t dataMode); // This function is deprecated. New applications should use // beginTransaction() to configure SPI settings. inline static void setClockDivider(uint8_t clockDiv) { if (clockDiv == SPI_CLOCK_DIV2) { setClockDivider_noInline(SPISettings(8000000, MSBFIRST, SPI_MODE0).ctar); } else if (clockDiv == SPI_CLOCK_DIV4) { setClockDivider_noInline(SPISettings(4000000, MSBFIRST, SPI_MODE0).ctar); } else if (clockDiv == SPI_CLOCK_DIV8) { setClockDivider_noInline(SPISettings(2000000, MSBFIRST, SPI_MODE0).ctar); } else if (clockDiv == SPI_CLOCK_DIV16) { setClockDivider_noInline(SPISettings(1000000, MSBFIRST, SPI_MODE0).ctar); } else if (clockDiv == SPI_CLOCK_DIV32) { setClockDivider_noInline(SPISettings(500000, MSBFIRST, SPI_MODE0).ctar); } else if (clockDiv == SPI_CLOCK_DIV64) { setClockDivider_noInline(SPISettings(250000, MSBFIRST, SPI_MODE0).ctar); } else { /* clockDiv == SPI_CLOCK_DIV128 */ setClockDivider_noInline(SPISettings(125000, MSBFIRST, SPI_MODE0).ctar); } } static void setClockDivider_noInline(uint32_t clk); // 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() { } inline static void detachInterrupt() { } // Teensy 3.x can use alternate pins for these 3 SPI signals. inline static void setMOSI(uint8_t pin) __attribute__((always_inline)) { SPCR.setMOSI(pin); } inline static void setMISO(uint8_t pin) __attribute__((always_inline)) { SPCR.setMISO(pin); } inline static void setSCK(uint8_t pin) __attribute__((always_inline)) { SPCR.setSCK(pin); } 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 }; #endif extern SPIClass SPI; #endif