EM73MA89B Datasheet, PDF (38/64 Pages) ELAN Microelectronics Corp – 4-BIT MICRO-CONTROLLER FOR LCD PRODUCT

RESETTING FUNCTION
EM73MA89B
4-BIT MICRO-CONTROLLER FOR LCD PRODUCT
Preliminary
When CPU in normal working condition and RESET pin is held in low level for three instruction cycles at least,
then CPU begins to initialize the whole internal states, 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
Program counter
Status flag
Interrupt enable flip-flop ( EI )
MASK0 ,1, 2, 3
Interrupt latch ( IL )
P3, 9, 10, 11, 12, 13, 14, 16, 18, 19, 20, 21, 22,
25, 27, 28, 29
P0, 1, 2, 4, 5, 6, 7, 8, 17, 23, 24
CLK, LXIN
Initial value
0000h
01h
00h
00h
00h
00h
0Fh
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.
10.15.2002 (V1.3) 38