static const struct rt_i2c_bit_ops stm32_bit_ops_default =
{
    .data     = RT_NULL,
    .set_sda  = stm32_set_sda,
    .set_scl  = stm32_set_scl,
    .get_sda  = stm32_get_sda,
    .get_scl  = stm32_get_scl,
    .udelay   = stm32_udelay,
    .delay_us = 1,
    .timeout  = 20
};