Merge SoftI2C timer={0,1} code paths, adjust timing according to I2C spec (63cbb8fa) · Commits · derf / multipass

src/arch/msp430fr5969lp/arch.cc

+8 −2

Original line number	Diff line number	Diff line
		@@ -104,10 +104,16 @@ volatile char run_loop = 0;

		void Arch::delay_us(unsigned int const us)
		{
		if (us < 10) {
		for (unsigned int i = 0; i < us; i++) {
		__delay_cycles(F_CPU / 1000000UL);
		}
		} else {
		for (unsigned int i = 0; i < us/10; i++) {
		__delay_cycles(F_CPU / 100000UL);
		}
		}
		}
		void Arch::delay_ms(unsigned int const ms)
		{
		for (unsigned int i = 0; i < ms; i++) {

src/driver/soft_i2c.cc

+25 −159

Original line number	Diff line number	Diff line
		@@ -11,6 +11,7 @@
		#error "SOFTI2C_TIMER and TIMER_CYCLES are mutually exclusive"
		#endif
		#include "driver/timer.h"
		volatile unsigned char timer_done = 0;
		#endif

		#ifdef SOFTI2C_PULLUP_INTERNAL
		@@ -30,171 +31,33 @@
		#define SCL_LOW gpio.output(scl)
		#endif /* SOFTI2C_PULLUP */

		#ifndef SOFTI2C_TIMER

		#if F_I2C < 50000
		#define I2C_WAIT arch.delay_us((500000UL / F_I2C) - 10)
		#else
		#define I2C_WAIT
		#endif /* !SOFTI2C_TIMER */

		signed char SoftI2C::setup()
		{
		#ifdef SOFTI2C_PULLUP_EXTERNAL
		gpio.output(sda_pull);
		gpio.output(scl_pull);
		#endif
		#ifdef SOFTI2C_PULLUP_FIXED_GPIO
		#if MULTIPASS_ARCH_msp430fr5969lp
		gpio.output(GPIO::p1_4, 1);
		gpio.output(GPIO::p1_5, 1);
		#else
		#error "softi2c_pullup=gpio not supported on this architecture"
		#endif /* MULTIPASS_ARCH_* */
		#endif /* SOFTI2C_PULLUP_FIXED_GPIO */
		SDA_HIGH;
		SCL_HIGH;
		return 0;
		}

		void SoftI2C::start()
		{
		SDA_HIGH;
		SCL_HIGH;
		I2C_WAIT;
		SDA_LOW;
		I2C_WAIT;
		SCL_LOW;
		}

		void SoftI2C::stop()
		{
		SCL_LOW;
		I2C_WAIT;
		SDA_LOW;
		I2C_WAIT;
		SCL_HIGH;
		I2C_WAIT;
		SDA_HIGH;
		}

		bool SoftI2C::tx(unsigned char byte)
		{
		unsigned char got_ack = 0;
		for (unsigned char i = 0; i <= 8; i++) {
		if ((byte & 0x80) \|\| (i == 8)) {
		SDA_HIGH;
		} else {
		SDA_LOW;
		}
		byte <<= 1;
		I2C_WAIT;
		SCL_HIGH;
		while (!gpio.read(scl)) ;
		I2C_WAIT;
		if (i == 8) {
		if (!gpio.read(sda)) {
		got_ack = 1;
		}
		}
		SCL_LOW;
		I2C_WAIT;
		}
		return got_ack;
		}

		unsigned char SoftI2C::rx(bool send_ack)
		{
		unsigned char byte = 0;
		SDA_HIGH;
		for (unsigned char i = 0; i <= 8; i++) {
		I2C_WAIT;
		SCL_HIGH;
		while (!gpio.read(scl)) ;
		I2C_WAIT;
		if ((i < 8) && gpio.read(sda)) {
		byte \|= 1 << (7 - i);
		}
		I2C_WAIT;
		SCL_LOW;
		I2C_WAIT;
		if ((i == 7) && send_ack) {
		SDA_LOW;
		} else if ((i == 8) && send_ack) {
		SDA_HIGH;
		}
		}
		return byte;
		}

		void SoftI2C::scan(unsigned int *results)
		{
		unsigned char i2caddr;
		for (unsigned char address = 0; address < 128; address++) {

		i2caddr = (address << 1) \| 0;

		start();

		if (tx(i2caddr)) {
		results[address / (8 * sizeof(unsigned int))] \|= 1 << (address % (8 * sizeof(unsigned int)));
		stop();
		}
		}
		stop();
		}

		signed char SoftI2C::xmit(unsigned char address,
		unsigned char tx_len, unsigned char *tx_buf,
		unsigned char rx_len, unsigned char *rx_buf)
		inline void i2c_wait()
		{
		unsigned char i;

		if (tx_len) {
		start();
		tx((address << 1) \| 0);

		for (i = 0; i < tx_len; i++) {
		tx(tx_buf[i]);
		}
		}
		if (rx_len) {
		start();
		tx((address << 1) \| 1);

		for (i = 1; i <= rx_len; i++) {
		rx_buf[i-1] = rx((i < rx_len) * 1);
		}
		}

		stop();

		return 0;
		}

		#else

		volatile unsigned char timer_done = 0;

		#ifdef SOFTI2C_TIMER
		/*
		* Note: On MSP430, if F_CPU / F_I2C < 60 (approx.), await_timer() does not
		* Note: On MSP430, if F_CPU / F_I2C < 60 (approx.), i2c_wait() does not
		* work. Probably related to missed interrupts / not enough cycles between
		* start and idle? We work around this for now by simulating an immediate
		* return in these cases.
		*/
		#if MULTIPASS_ARCH_msp430fr5969lp && ((F_CPU / F_I2C) < 60)
		inline void await_timer() {}
		#else
		inline void await_timer()
		{
		timer_done = 0;
		timer.start(1);
		while (!timer_done) {
		arch.idle();
		}
		timer.stop();
		}
		#endif
		#else /* !SOFTI2C_TIMER */
		#if (500000UL / F_I2C) > 11
		arch.delay_us((500000UL / F_I2C) - 10);
		#else
		arch.delay_us(500000UL / F_I2C);
		#endif
		#endif /* SOFTI2C_TIMER */
		}

		signed char SoftI2C::setup()
		{
		@@ -212,6 +75,7 @@ signed char SoftI2C::setup()
		#endif /* SOFTI2C_PULLUP_FIXED_GPIO */
		SDA_HIGH;
		SCL_HIGH;
		#ifdef SOFTI2C_TIMER
		/*
		* I2C frequency is the time between two SCL low->high transitions
		* (or high->low, whatever you prefer). For the timer, we need to set the
		@@ -221,6 +85,7 @@ signed char SoftI2C::setup()
		* Timer Freq [kHz] = I2C Freq [Hz] * 2 / 1000
		*/
		timer.setup_khz(F_I2C / 500);
		#endif
		return 0;
		}

		@@ -228,21 +93,22 @@ void SoftI2C::start()
		{
		SDA_HIGH;
		SCL_HIGH;
		await_timer();
		i2c_wait(); // t_{SU,STA} >= 4.7 µs (für Sr)
		SDA_LOW;
		await_timer();
		i2c_wait(); // t_{HD,STA} >= 4 µs
		SCL_LOW;
		await_timer();
		i2c_wait();
		}

		void SoftI2C::stop()
		{
		SCL_LOW;
		SDA_LOW;
		await_timer();
		i2c_wait();
		SCL_HIGH;
		await_timer();
		i2c_wait(); // t_{SU,STO} >= 4 µs
		SDA_HIGH;
		i2c_wait(); // t_{BUF} >= 4.7 µs
		}

		bool SoftI2C::tx(unsigned char byte)
		@@ -255,8 +121,9 @@ bool SoftI2C::tx(unsigned char byte)
		SDA_LOW;
		}
		byte <<= 1;
		i2c_wait();
		SCL_HIGH;
		await_timer();
		i2c_wait();
		while (!gpio.read(scl)) ;
		if (i == 8) {
		if (!gpio.read(sda)) {
		@@ -264,7 +131,6 @@ bool SoftI2C::tx(unsigned char byte)
		}
		}
		SCL_LOW;
		await_timer();
		}
		return got_ack;
		}
		@@ -274,14 +140,14 @@ unsigned char SoftI2C::rx(bool send_ack)
		unsigned char byte = 0;
		SDA_HIGH;
		for (unsigned char i = 0; i <= 8; i++) {
		i2c_wait();
		SCL_HIGH;
		await_timer();
		i2c_wait();
		while (!gpio.read(scl)) ;
		if ((i < 8) && gpio.read(sda)) {
		byte \|= 1 << (7 - i);
		}
		SCL_LOW;
		await_timer();
		if ((i == 7) && send_ack) {
		SDA_LOW;
		} else if ((i == 8) && send_ack) {
		@@ -336,10 +202,10 @@ signed char SoftI2C::xmit(unsigned char address,
		return 0;
		}

		#ifdef SOFTI2C_TIMER
		ON_TIMER_INTERRUPT_head
		timer_done = 1;
		ON_TIMER_INTERRUPT_tail

		#endif

		#if SOFTI2C_PULLUP_EXTERNAL

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