PCF8523_R_CS3
err = write_reg(sc, PCF8523_R_CS3, PCF8523_B_CS3_PM_STD);
if ((err = read_reg(sc, PCF8523_R_CS3, &cs3)) != 0) {
err = write_reg(sc, PCF8523_R_CS3, PCF8523_B_CS3_PM_DSNBM);