EM73880 Datasheet, PDF (27/40 Pages) ELAN Microelectronics Corp – 4-BIT MICRO-CONTROLLER FOR LCD PRODUCT

EM73880
4-BIT MICRO-CONTROLLER FOR LCD PRODUCT
Preliminary
RESETTING FUNCTION
When CPU in normal working condition and RESET pin holds in low level for three instruction cycles at least,
then CPU begins to initialize the whole internal states, and when RESET pin changes to high level, CPU begins
to work in normal condition.
The CPU internal state during reset condition is as following table :
Hardware condition in RESET state
Initial value
Program counter
0000h
Status flag
01h
Interrupt enable flip-flop ( EI )
00h
MASK0 ,1, 2, 3
00h
Interrupt latch ( IL )
00h
P4, P5, P10, 11,14, 16, 19, 25, 27, 28, 29, 31 00h
P4, 8, 17, 23, 24
0Fh
Both oscillator
Start oscillation
The RESET pin is a hysteresis input pin and it has a pull-up resistor available by mask option.
The simplest RESET circuit is connect RESET pin with a capacitor to V_SS and a diode to V_DD.
RESET
* This specification are subject to be changed without notice.
11.30.2001 27