I2C_DS
HWRITE4(sc, I2C_DS, addr);
HWRITE4(sc, I2C_DS, ((uint8_t *)cmdbuf)[i]);
HWRITE4(sc, I2C_DS, addr);
((uint8_t *)databuf)[i] = HREAD4(sc, I2C_DS);
HWRITE4(sc, I2C_DS, ((uint8_t *)databuf)[i]);