mirror of
https://github.com/arduino/Arduino.git
synced 2024-12-10 21:24:12 +01:00
325 lines
10 KiB
C++
325 lines
10 KiB
C++
/*
|
|
* Copyright (c) 2010 by Cristian Maglie <c.maglie@arduino.cc>
|
|
* Copyright (c) 2014 by Paul Stoffregen <paul@pjrc.com> (Transaction API)
|
|
* Copyright (c) 2014 by Matthijs Kooijman <matthijs@stdin.nl> (SPISettings AVR)
|
|
* Copyright (c) 2014 by Andrew J. Kroll <xxxajk@gmail.com> (atomicity fixes)
|
|
* 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 <Arduino.h>
|
|
|
|
// SPI_HAS_TRANSACTION means SPI has beginTransaction(), endTransaction(),
|
|
// usingInterrupt(), and SPISetting(clock, bitOrder, dataMode)
|
|
#define SPI_HAS_TRANSACTION 1
|
|
|
|
// SPI_HAS_NOTUSINGINTERRUPT means that SPI has notUsingInterrupt() method
|
|
#define SPI_HAS_NOTUSINGINTERRUPT 1
|
|
|
|
// SPI_ATOMIC_VERSION means that SPI has atomicity fixes and what version.
|
|
// This way when there is a bug fix you can check this define to alert users
|
|
// of your code if it uses better version of this library.
|
|
// This also implies everything that SPI_HAS_TRANSACTION as documented above is
|
|
// available too.
|
|
#define SPI_ATOMIC_VERSION 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 an 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
|
|
#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_MODE0 0x00
|
|
#define SPI_MODE1 0x04
|
|
#define SPI_MODE2 0x08
|
|
#define SPI_MODE3 0x0C
|
|
|
|
#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
|
|
|
|
// 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 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);
|
|
// And this does the opposite.
|
|
static void notUsingInterrupt(uint8_t interruptNumber);
|
|
// Note: the usingInterrupt and notUsingInterrupt functions should
|
|
// not to be called from ISR context or inside a transaction.
|
|
// For details see:
|
|
// https://github.com/arduino/Arduino/pull/2381
|
|
// https://github.com/arduino/Arduino/pull/2449
|
|
|
|
// 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) {
|
|
uint8_t sreg = SREG;
|
|
noInterrupts();
|
|
|
|
#ifdef SPI_AVR_EIMSK
|
|
if (interruptMode == 1) {
|
|
interruptSave = SPI_AVR_EIMSK;
|
|
SPI_AVR_EIMSK &= ~interruptMask;
|
|
SREG = sreg;
|
|
} else
|
|
#endif
|
|
{
|
|
interruptSave = sreg;
|
|
}
|
|
}
|
|
|
|
#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;
|
|
}
|
|
|
|
// Write to the SPI bus (MOSI pin) and also receive (MISO pin)
|
|
inline static uint8_t transfer(uint8_t data) {
|
|
SPDR = data;
|
|
/*
|
|
* The following NOP introduces a small delay that can prevent the wait
|
|
* loop form iterating when running at the maximum speed. This gives
|
|
* about 10% more speed, even if it seems counter-intuitive. At lower
|
|
* speeds it is unnoticed.
|
|
*/
|
|
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;
|
|
asm volatile("nop"); // See transfer(uint8_t) function
|
|
while (!(SPSR & _BV(SPIF))) ;
|
|
out.msb = SPDR;
|
|
SPDR = in.lsb;
|
|
asm volatile("nop");
|
|
while (!(SPSR & _BV(SPIF))) ;
|
|
out.lsb = SPDR;
|
|
} else {
|
|
SPDR = in.lsb;
|
|
asm volatile("nop");
|
|
while (!(SPSR & _BV(SPIF))) ;
|
|
out.lsb = SPDR;
|
|
SPDR = in.msb;
|
|
asm volatile("nop");
|
|
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
|
|
uint8_t sreg = SREG;
|
|
#endif
|
|
noInterrupts();
|
|
#ifdef SPI_AVR_EIMSK
|
|
if (interruptMode == 1) {
|
|
SPI_AVR_EIMSK = interruptSave;
|
|
SREG = sreg;
|
|
} 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 initialized;
|
|
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;
|
|
|
|
#endif
|