HOURS_REG
I2C_WRITE(sc, HOURS_REG, bintobcd(dt->dt_hour));
dt->dt_hour = bcdtobin(I2C_READ(sc, HOURS_REG));
hours_reg = POWER_READ(sc, HOURS_REG);
POWER_WRITE(sc, HOURS_REG, bintobcd(dt->dt_hour));