betaflight/src/main/drivers/bus_i2c_soft.c

/*
 * This file is part of Cleanflight.
 *
 * Cleanflight is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Cleanflight is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Cleanflight.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <stdbool.h>
#include <stdint.h>

#include <platform.h>

#include "build_config.h"
#include "bus_i2c.h"
#include "drivers/io.h"

// Software I2C driver, using same pins as hardware I2C, with hw i2c module disabled.
// Can be configured for I2C2 pinout (SCL: PB10, SDA: PB11) or I2C1 pinout (SCL: PB6, SDA: PB7)

#ifdef SOFT_I2C

static IO_t scl;
static IO_t sda;
static volatile uint16_t i2cErrorCount = 0;

#define SCL_H         IOHi(scl)
#define SCL_L         IOLo(scl)

#define SDA_H         IOHi(sda)
#define SDA_L         IOLo(sda)

#define SCL_read      IORead(scl)
#define SDA_read      IORead(sda)

#if !defined(SOFT_I2C_SCL) || !defined(SOFT_I2C_SDA)
#error "Must define the software i2c pins (SOFT_I2C_SCL and SOFT_I2C_SDA) in target.h"
#endif

static void I2C_delay(void)
{
	volatile int i = 7;
	while (i) {
		i--;
	}
}

static bool I2C_Start(void)
{
	SDA_H;
	SCL_H;
	I2C_delay();
	if (!SDA_read) {
		return false;
	}
	SDA_L;
	I2C_delay();
	if (SDA_read) {
		return false;
	}
	SDA_L;
	I2C_delay();
	return true;
}

static void I2C_Stop(void)
{
	SCL_L;
	I2C_delay();
	SDA_L;
	I2C_delay();
	SCL_H;
	I2C_delay();
	SDA_H;
	I2C_delay();
}

static void I2C_Ack(void)
{
	SCL_L;
	I2C_delay();
	SDA_L;
	I2C_delay();
	SCL_H;
	I2C_delay();
	SCL_L;
	I2C_delay();
}

static void I2C_NoAck(void)
{
	SCL_L;
	I2C_delay();
	SDA_H;
	I2C_delay();
	SCL_H;
	I2C_delay();
	SCL_L;
	I2C_delay();
}

static bool I2C_WaitAck(void)
{
	SCL_L;
	I2C_delay();
	SDA_H;
	I2C_delay();
	SCL_H;
	I2C_delay();
	if (SDA_read) {
		SCL_L;
		return false;
	}
	SCL_L;
	return true;
}

static void I2C_SendByte(uint8_t byte)
{
	uint8_t i = 8;
	while (i--) {
		SCL_L;
		I2C_delay();
		if (byte & 0x80) {
			SDA_H;
		}
		else {
			SDA_L;
		}
		byte <<= 1;
		I2C_delay();
		SCL_H;
		I2C_delay();
	}
	SCL_L;
}

static uint8_t I2C_ReceiveByte(void)
{
	uint8_t i = 8;
	uint8_t byte = 0;

	SDA_H;
	while (i--) {
		byte <<= 1;
		SCL_L;
		I2C_delay();
		SCL_H;
		I2C_delay();
		if (SDA_read) {
			byte |= 0x01;
		}
	}
	SCL_L;
	return byte;
}

void i2cInit(I2CDevice device)
{
	UNUSED(device);

	scl = IOGetByTag(IO_TAG(SOFT_I2C_SCL));
	sda = IOGetByTag(IO_TAG(SOFT_I2C_SDA));

	IOConfigGPIO(scl, IOCFG_OUT_OD);
	IOConfigGPIO(sda, IOCFG_OUT_OD);
}

bool i2cWriteBuffer(I2CDevice device, uint8_t addr, uint8_t reg, uint8_t len, uint8_t * data)
{
    UNUSED(device);
    
	int i;
	if (!I2C_Start()) {
		i2cErrorCount++;
		return false;
	}
	I2C_SendByte(addr << 1 | I2C_Direction_Transmitter);
	if (!I2C_WaitAck()) {
		I2C_Stop();
		return false;
	}
	I2C_SendByte(reg);
	I2C_WaitAck();
	for (i = 0; i < len; i++) {
		I2C_SendByte(data[i]);
		if (!I2C_WaitAck()) {
			I2C_Stop();
			i2cErrorCount++;
			return false;
		}
	}
	I2C_Stop();
	return true;
}

bool i2cWrite(I2CDevice device, uint8_t addr, uint8_t reg, uint8_t data)
{
    UNUSED(device);
    
	if (!I2C_Start()) {
		return false;
	}
	I2C_SendByte(addr << 1 | I2C_Direction_Transmitter);
	if (!I2C_WaitAck()) {
		I2C_Stop();
		i2cErrorCount++;
		return false;
	}
	I2C_SendByte(reg);
	I2C_WaitAck();
	I2C_SendByte(data);
	I2C_WaitAck();
	I2C_Stop();
	return true;
}

bool i2cRead(I2CDevice device, uint8_t addr, uint8_t reg, uint8_t len, uint8_t *buf)
{
    UNUSED(device);
    
	if (!I2C_Start()) {
		return false;
	}
	I2C_SendByte(addr << 1 | I2C_Direction_Transmitter);
	if (!I2C_WaitAck()) {
		I2C_Stop();
		i2cErrorCount++;
		return false;
	}
	I2C_SendByte(reg);
	I2C_WaitAck();
	I2C_Start();
	I2C_SendByte(addr << 1 | I2C_Direction_Receiver);
	I2C_WaitAck();
	while (len) {
		*buf = I2C_ReceiveByte();
		if (len == 1) {
			I2C_NoAck();
		}
		else {
			I2C_Ack();
		}
		buf++;
		len--;
	}
	I2C_Stop();
	return true;
}

uint16_t i2cGetErrorCounter(void)
{
	return i2cErrorCount;
}

#endif