Model-specific configuration registers Placement of configuration values "~" means the bit is a negated boolean. Sometimes values overlap, depending on MCU model. In STC15 series, the first 13 MCS bytes have active values. Generally, unused bits should be set to 1. MCS0 ---- MSB 7 6 5 4 3 2 1 0 LSB RSPEN RSPEN := RESET pin enable MCS1 ---- MSB 7 6 5 4 3 2 1 0 LSB EEIH LVRS LVD2 LVD1 LVD0 EEIH := inhibit EEPROM writes in low-voltage conditions enable LVRS := low-voltage reset enable LVD2...LVD0 := low voltage detection threshold LVD2 LVD1 LVD0 value 0 0 0 setting 0 (e.g. 3.14V) 0 0 1 setting 1 (e.g. 3.28V) 0 1 0 setting 2 (e.g. 3.43V) 0 1 1 setting 3 (e.g. 3.61V) 1 0 0 setting 4 (e.g. 3.82V) 1 0 1 setting 5 (e.g. 4.05V) 1 1 0 unknown 1 1 1 unknown The exact voltages depend on MCU model. MCS2 ---- MSB 7 6 5 4 3 2 1 0 LSB ~WDEN ~WDSTP WDPS2 WDPS1 WDPS0 ~WDEN := watchdog enable after power-on-reset ~WDSTP := stop watchdog counter in idle mode WDPS2...WDPS0 := watchdog counter prescaler WDPS2 WDPS1 WDPS0 divisior 0 0 0 2 0 0 1 4 0 1 0 8 0 1 1 16 1 0 0 32 1 0 1 64 1 1 0 128 1 1 1 256 This is completely similar to STC12. MCS3...MCS11 ------------ All bytes set to 0xff. MCS12 ----- MSB 7 6 5 4 3 2 1 0 LSB ~EREE ~BSLD ~EREE := enable eeprom erase next time MCU is programmed ~BSLD := enable BSL pin detect; i.e. BSL is only enabled if P1.0/P1.1 (or others, depends on MCU model) are held low on POR. This is like MCS3 of STC12.