STC89 series WDT_CONTR ( E1H )
Reset Value
xx00,0000
Mnemonic Add
WDT_CONTR E1h
Name
Bit7 Bit6 Bit5
Bit4
Bir3 Bit2 Bit1 Bit0
Wact-Dog-Timer Control register
-
-
EN_WDT CLR_WDT IDL_WDT
PS2 PS1 PS0
STC15F204EA series MCU auto enable watch dog timer after ISP upgrade, but not in STC89 series, so
STC15F204EA series’s watch dog is more reliable.
EEPROM
SFR associated with EEPROM
STC15Fxx
Address
STC89xx
Mnemonic
Description
ISP/IAP Flash data register
IAP_DATA
IAP_ADDRH
IAP_ADDRL
IAP_CMD
C2H
C3H
C4H
C5H
C6H
C7H
E2H
E3G
E4H
E5H
E6H
E7H
ISP/IAP Flash HIGH address register
ISP/IAP Flash LOW address register
ISP/IAP Flash command register
ISP/IAP command trigger register
ISP/IAP control register
IAP_TRIG
IAP_CONTR
STC15F204EA series write 5AH and A5H sequential to trigger EEPROM flash command, and STC89 series
write 46H and B9H sequential to trigger EEPROM flash command.
STC15F204EA series EEPROM start address all location at 0000H, but STC89 series is not.
Power consumption
Power consumption consists of two parts: crystal oscillator amplifier circuits and digital circuits.
STC15F204EA series have no crystal oscillator amplifier circuits, so its consumption is lower than STC89
series. For digital circuits, the higher clock frequency, the greater the power consumption. STC15F204EA
series MCU instruction execution speed is faster than the STC89 series MCU 3~24 times in the same
working environment, so if you need to achieve the same efficiency, STC15F204EA series required
frequency is lower than STC89 series MCU.
PowerDown Wakeup
STC15F204EA series MCU wake-up support for rising edge or falling edge depend on the external interrupt
mode, but STC89 series only support for low level.
About reset circuit
For STC89 series, if the system frequency is below 12MHz, the external reset circuit is not required. Reset
pin can be connected to ground through the 1K resistor or can be connected directly to ground. The proposal
to create PCB to retain RC reset circuit.
While STC15F204EA series has an internal high-reliability reset circuit and does not need external reset
circuit.
About Clock oscillator
For STC89 series, if you need to use internal RC oscillator, XTAL1 pin and XTAL2 pin must be floating. If
you use a external active crystal oscillator, clock signal input from XTAL1 pin and XTAL2 pin floating.
While STC15F204EA series only has an high-precision RC oscillator with temperature dirfting ±1% and has
removed expensive external crystal oscillator.
About power
Power at both ends need to add a 47uF electrolytic capacitor and a 0.1uF capacitor, to remove the coupling
and filtering
251