em78p811 ELAN Microelectronics Corp, em78p811 Datasheet - Page 18

• Manufacturer Part Number: em78p811
• Description: 8-bit Micro-controller
• Manufacturer: ELAN Microelectronics Corp

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* This specification is subject to be changed without notice.
8. IOCE (Bias,PLL Control Register)
* Bit 0 ~ 7 (/PH#) Control bit used to enable the pull-high of PORT7(#) pin.
1: Enable internal pull-high
0: Disable internal pull-high
* Bit 0 :SC (SCAN KEY signal ) 0/1 = disable/enable. Once you enable this bit , all of the LCD signal will have
PAGE0 :
a.
b.
c.
d.
e.
f.
g.
h.
P9SH
a low pulse during a common period. This pulse has 30us width. Please use the procedure to implement the
key scan function. NOTE! Please connect a transistor with common signal to separate IO PORT.
7
set port7 as input port
set IOCD page0 port7 pull high
enable scan key signal
Once push a key . Set RA(6)=1 and switch to normal mode.
Blank LCD. Disable scan key signal.
Set P6S =0. Port6 sent probe signal to port7 and read port7. Get the key.
Note!! A probe signal should be delay a instruction at least to another probe signal.
Set P6S =1. Port6 as LCD signal. Enable LCD.
Fig.10. Key scan circuit
P9SL
6
P63
P62
P61
P60
P6S
5
Bias3
4
P73
Bias2
3
P72
Bias1
2
17
KEY5
P71
1
0
SC
0
KEY1
KEY2
KEY3
KEY4
P70
8-bit OTP Micro-controller
EM78P811