Exemple #1
0
/* sla includes all 8 bits (with r/w bit), assums master transmit */
uint8_t u8g_i2c_start(uint8_t sla)
{
    register uint8_t status;

    /* send start */
    TWCR = _BV(TWINT) |  _BV(TWSTA)  |  _BV(TWEN);

    /* wait */
    if ( u8g_i2c_wait(_BV(TWINT), 1) == 0 )
        return 0;

    status = TW_STATUS;

    /* check status after start */
    if ( status != TW_START && status != TW_REP_START )
    {
        u8g_i2c_set_error(U8G_I2C_ERR_BUS, 1);
        return 0;
    }

    /* set slave address */
    TWDR = sla;

    /* enable sla transfer */
    TWCR = _BV(TWINT)  |  _BV(TWEN);

    /* wait */
    if ( u8g_i2c_wait(_BV(TWINT), 2) == 0 )
        return 0;

    if ( u8g_i2c_opt & U8G_I2C_OPT_NO_ACK )
    {
        /* do not check for ACK */
    }
    else
    {
        status = TW_STATUS;
        /* check status after sla */
        if ( status != TW_MT_SLA_ACK )
        {
            u8g_i2c_set_error(U8G_I2C_ERR_BUS, 2);
            return 0;
        }
    }

    return 1;
}
Exemple #2
0
uint8_t u8g_i2c_wait(uint8_t mask, uint8_t pos)
{
    volatile uint16_t cnt = 2000;	/* timout value should be > 280 for 50KHz Bus and 16 Mhz CPU, however the start condition might need longer */
    while( !(TWCR & mask) )
    {
        if ( cnt == 0 )
        {
            u8g_i2c_set_error(U8G_I2C_ERR_TIMEOUT, pos);
            return 0; /* error */
        }
        cnt--;
    }
    return 1;	/* all ok */
}
Exemple #3
0
uint8_t u8g_i2c_send_byte(uint8_t data)
{
    register uint8_t status;
    TWDR = data;
    TWCR = _BV(TWINT)  |  _BV(TWEN);
    if ( u8g_i2c_wait(_BV(TWINT), 3) == 0 )
        return 0;
    status = TW_STATUS;

    if ( status != TW_MT_DATA_ACK )
    {
        u8g_i2c_set_error(U8G_I2C_ERR_BUS, 3);
        return 0;
    }

    return 1;
}
Exemple #4
0
uint8_t u8g_i2c_send_byte(uint8_t data)
{
    register uint8_t status;
    TWDR = data;
    TWCR = _BV(TWINT)  |  _BV(TWEN);
    if ( u8g_i2c_wait(_BV(TWINT), 3) == 0 )
        return 0;

    if ( u8g_i2c_opt & U8G_I2C_OPT_NO_ACK )
    {
        /* do not check for ACK */
    }
    else
    {
        status = TW_STATUS;
        if ( status != TW_MT_DATA_ACK )
        {
            u8g_i2c_set_error(U8G_I2C_ERR_BUS, 3);
            return 0;
        }
    }

    return 1;
}