GMS81C50 Datasheet, PDF (99/99 Pages) Hynix Semiconductor – 8-BIT SINGLE CHIP MICROCONTROLLERS

Appendix B. Programmer’s guide
3. Key Scan
To secure the key board scanning , read the input port after
minimum 60uS delay time from output port set to `Low `.
This time delay is for the port rising time depend on the in-
put pull-up resistor .
; program example ,See the Figure B-1 circuit.
ldm R1,#1111_1110b ;R10 port set to LOW
call delay_60uS
;60uS time delay routine
lda R0
;R0 port Read
R0 port Read timing
R10
60uS
R11
60uS
< Fig B-2 , Input with pull-up port read time method >
* Current Consumption
The current consumption during the Pulse transmission de-
pends on the external circuit and each Protocol. Normally
, if you used Fig B-1 circuit., the operation current is 15mA
~ 25mA (Max 45mA). But this value is normal case. Some
special protocol can be possible to consume more larger
current.
B-4