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 "gpio.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

#ifdef SOFT_I2C_PB1011
#define SCL_H         GPIOB->BSRR = Pin_10
#define SCL_L         GPIOB->BRR  = Pin_10

#define SDA_H         GPIOB->BSRR = Pin_11
#define SDA_L         GPIOB->BRR  = Pin_11

#define SCL_read      (GPIOB->IDR & Pin_10)
#define SDA_read      (GPIOB->IDR & Pin_11)
#define I2C_PINS      (Pin_10 | Pin_11)
#define I2C_GPIO      GPIOB
#endif

#ifdef SOFT_I2C_PB67
#define SCL_H         GPIOB->BSRR = Pin_6
#define SCL_L         GPIOB->BRR  = Pin_6

#define SDA_H         GPIOB->BSRR = Pin_7
#define SDA_L         GPIOB->BRR  = Pin_7

#define SCL_read      (GPIOB->IDR & Pin_6)
#define SDA_read      (GPIOB->IDR & Pin_7)
#define I2C_PINS      (Pin_6 | Pin_7)
#define I2C_GPIO      GPIOB
#endif

#ifndef SCL_H
#error Need to define SOFT_I2C_PB1011 or SOFT_I2C_PB67 (see board.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(I2C_TypeDef * I2C)
{
    gpio_config_t gpio;

    gpio.pin = I2C_PINS;
    gpio.speed = Speed_2MHz;
    gpio.mode = Mode_Out_OD;
    gpioInit(I2C_GPIO, &gpio);
}

bool i2cWriteBuffer(uint8_t addr, uint8_t reg, uint8_t len, uint8_t * data)
{
    int i;
    if (!I2C_Start()) {
	    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();
            return false;
        }
    }
    I2C_Stop();
    return true;
}

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

bool i2cRead(uint8_t addr, uint8_t reg, uint8_t len, uint8_t *buf)
{
    if (!I2C_Start()) {
	    return false;
	}
    I2C_SendByte(addr << 1 | I2C_Direction_Transmitter);
    if (!I2C_WaitAck()) {
        I2C_Stop();
        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)
{
    // TODO maybe fix this, but since this is test code, doesn't matter.
    return 0;
}

#endif