W921E400A Datasheet, PDF (36/53 Pages) Winbond – 4-BIT MICROCONTROLLER

W921E400A/W921C400
6.13 Initial Condition Register of EPROM Program Method
There is one 4-bit of the initial condition register (not part of the RAM) in W921E400A to control the
micro-controller initial status after power-on. The format is described as following:
INI register: (initial value = 0FH)
b3
b2
b1
b0
0: f osc acts as RC oscillator type
1: f osc acts as crystal type
Reserved
Reserved
Reserved
6.14 Reset
The W921E400A/W921C400 provides two reset methods, pull low RESET pin and watch dog timer
reset.
6.14.1 Reset by RESET
RESET
256 machine
cycle
Reset all
control reg.
Program executed
from address 000H
As RESET pin is pulled low, system and all control registers are reset to initial state. After RESET
pin is in high level, system will delay 256 machine cycle time then program is executed from address
000H.
6.14.2 Reset by Watch Dog Timer
STTM0.1
256 machine
cycle
Program executed
from address 000H
Reset all control regs
except STTM0.1
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