i2c_bitbang.c

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#include "i2c.h"
#include "cfg/cfg_i2c.h"

#define LOG_LEVEL  I2C_LOG_LEVEL
#define LOG_FORMAT I2C_LOG_FORMAT

#include <cfg/log.h>
#include <cfg/macros.h>
#include <cfg/module.h>

#include <drv/timer.h>
#include <cpu/irq.h>

#include "hw/hw_i2c_bitbang.h"

INLINE bool i2c_bitbang_start(void)
{
    SDA_HI;
    SCL_HI;
    I2C_HALFBIT_DELAY();
    SDA_LO;
    I2C_HALFBIT_DELAY();
    ASSERT(!SDA_IN);
    return !SDA_IN;
}

void i2c_bitbang_stop(void)
{
    SDA_LO;
    SCL_HI;
    I2C_HALFBIT_DELAY();
    SDA_HI;
}

bool i2c_bitbang_put(uint8_t _data)
{
    /* Add ACK bit */
    uint16_t data = (_data << 1) | 1;

    for (uint16_t i = 0x100; i != 0; i >>= 1)
    {
        SCL_LO;
        if (data & i)
            SDA_HI;
        else
            SDA_LO;
        I2C_HALFBIT_DELAY();

        SCL_HI;
        I2C_HALFBIT_DELAY();
    }

    bool ack = !SDA_IN;
    SCL_LO;
    I2C_HALFBIT_DELAY();
    return ack;
}

bool i2c_bitbang_start_w(uint8_t id)
{
    id &= ~I2C_READBIT;
    /*
     * Loop on the select write sequence: when the device is busy
     * writing previously sent data it will reply to the SLA_W
     * control byte with a NACK.  In this case, we must
     * keep trying until the deveice responds with an ACK.
     */
    ticks_t start = timer_clock();
    while (i2c_bitbang_start())
    {
        if (i2c_bitbang_put(id))
            return true;
        else if (timer_clock() - start > ms_to_ticks(CONFIG_I2C_START_TIMEOUT))
        {
            LOG_ERR("Timeout on I2C start write\n");
            break;
        }
        //LOG_INFO("Rep start\n");
    }

    return false;
}

bool i2c_bitbang_start_r(uint8_t id)
{
    id |= I2C_READBIT;
    if (i2c_bitbang_start())
    {
        if (i2c_bitbang_put(id))
            return true;

        LOG_ERR("NACK on I2c start read\n");
    }

    return false;
}

int i2c_bitbang_get(bool ack)
{
    uint8_t data = 0;
    for (uint8_t i = 0x80; i != 0; i >>= 1)
    {
        SCL_LO;
        I2C_HALFBIT_DELAY();
        SCL_HI;
        if (SDA_IN)
            data |= i;
        else
            data &= ~i;

        I2C_HALFBIT_DELAY();
    }
    SCL_LO;

    if (ack)
        SDA_LO;
    else
        SDA_HI;

    I2C_HALFBIT_DELAY();
    SCL_HI;
    I2C_HALFBIT_DELAY();
    SCL_LO;
    SDA_HI;
    /* avoid sign extension */
    return (int)(uint8_t)data;
}

MOD_DEFINE(i2c);

void i2c_bitbang_init(void)
{
    MOD_CHECK(timer);
    I2C_BITBANG_HW_INIT;
    SDA_HI;
    SCL_HI;
    MOD_INIT(i2c);
}