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/*
* Copyright 2020 Daniel Friesel
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include "driver/soft_i2c.h"
#include "driver/gpio.h"
#include "arch.h"
#ifndef F_I2C
#define F_I2C 100000
#endif
#ifdef SOFTI2C_TIMER
#include "driver/timer.h"
volatile unsigned char timer_done = 0;
#endif
#ifdef SOFTI2C_PULLUP_INTERNAL
#define SDA_HIGH gpio.input(sda, 1)
#define SDA_LOW gpio.output(sda, 0)
#define SCL_HIGH gpio.input(scl, 1)
#define SCL_LOW gpio.output(scl, 0)
#elif SOFTI2C_PULLUP_EXTERNAL
#define SDA_HIGH { gpio.input(sda); gpio.write(sda_pull, 1); }
#define SDA_LOW { gpio.write(sda_pull, 0); gpio.output(sda); }
#define SCL_HIGH { gpio.input(scl); gpio.write(scl_pull, 1); }
#define SCL_LOW { gpio.write(scl_pull, 0); gpio.output(scl); }
#else /* !SOFTI2C_PULLUP_{INTERNAL,EXTERNAL} */
#define SDA_HIGH gpio.input(sda)
#define SDA_LOW gpio.output(sda)
#define SCL_HIGH gpio.input(scl)
#define SCL_LOW gpio.output(scl)
#endif /* SOFTI2C_PULLUP */
inline void i2c_wait()
{
#ifdef SOFTI2C_TIMER
/*
* 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)
#else
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()
{
#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);
#elif MULTIPASS_ARCH_msp430fr5994lp
gpio.output(GPIO::p8_2, 1);
gpio.output(GPIO::p8_3, 1);
#else
#error "softi2c_pullup=gpio not supported on this architecture"
#endif /* MULTIPASS_ARCH_* */
#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
* time between SCL low->high and the following high->low transition
* (and vice versa), which is twice the desired I2C frequency. Also,
* timer.setup wants kHz and not Hz, so we have
* Timer Freq [kHz] = I2C Freq [Hz] * 2 / 1000
*/
timer.setup_khz(F_I2C / 500);
#endif
return 0;
}
void SoftI2C::start()
{
SDA_HIGH;
SCL_HIGH;
i2c_wait(); // t_{SU,STA} >= 4.7 µs (für Sr)
SDA_LOW;
i2c_wait(); // t_{HD,STA} >= 4 µs
SCL_LOW;
i2c_wait();
}
void SoftI2C::stop()
{
SCL_LOW;
SDA_LOW;
i2c_wait();
SCL_HIGH;
i2c_wait(); // t_{SU,STO} >= 4 µs
SDA_HIGH;
i2c_wait(); // t_{BUF} >= 4.7 µs
}
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;
i2c_wait();
// Avoid hanging indefinitely if the bus / device is stuck
for (unsigned char i = 0; i < 200 && !gpio.read(scl); i++) {
i2c_wait();
}
if (!gpio.read(scl)) {
return false;
}
if (i == 8) {
if (!gpio.read(sda)) {
got_ack = 1;
}
}
SCL_LOW;
}
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;
i2c_wait();
// Avoid hanging indefinitely if the bus / device is stuck
for (unsigned char i = 0; i < 200 && !gpio.read(scl); i++) {
i2c_wait();
}
if (!gpio.read(scl)) {
return false;
}
if ((i < 8) && gpio.read(sda)) {
byte |= 1 << (7 - i);
}
SCL_LOW;
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)
{
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;
}
#ifdef SOFTI2C_TIMER
ON_TIMER_INTERRUPT_head
timer_done = 1;
ON_TIMER_INTERRUPT_tail
#endif
#if SOFTI2C_PULLUP_EXTERNAL
#ifdef MULTIPASS_ARCH_msp430fr5969lp
SoftI2C i2c(GPIO::p1_6, GPIO::p1_7, GPIO::p1_4, GPIO::p1_5);
#elif MULTIPASS_ARCH_msp430fr5994lp
SoftI2C i2c(GPIO::p5_0, GPIO::p5_1, GPIO::p8_2, GPIO::p8_3);
#else
#error "softi2c_pullup = external not supported on this architecture"
#endif /* MULTIPASS_ARCH_* */
#else
#ifdef MULTIPASS_ARCH_esp8266
SoftI2C i2c(GPIO::d6, GPIO::d7);
#elif MULTIPASS_ARCH_arduino_nano
SoftI2C i2c(GPIO::pc4, GPIO::pc5);
#elif MULTIPASS_ARCH_blinkenrocket
SoftI2C i2c(GPIO::pc4, GPIO::pc5);
#elif MULTIPASS_ARCH_msp430fr5969lp
SoftI2C i2c(GPIO::p1_6, GPIO::p1_7);
#elif MULTIPASS_ARCH_msp430fr5994lp
SoftI2C i2c(GPIO::p5_0, GPIO::p5_1);
#elif MULTIPASS_ARCH_posix
SoftI2C i2c(GPIO::px00, GPIO::px01);
#endif /* MULTIPASS_ARCH_* */
#endif /* !SOFTI2C_PULLUP_EXTERNAL */
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