EM78862B View Datasheet(PDF) - ELAN Microelectronics
Part Name
Description
MFG CO.
'EM78862B' PDF : 40 Pages View PDF
EM78862B
8-Bit RISC Type Microprocessor
6.2.12 IOCE (Port9 GPIO/LCD Segment, Port6 GPIO/LCD Com,
LCD Bias, Scan Key Signal, Port7 Open Drain, Counter 1/2 Clock
Source, Counter1 Pre-Scaler Control Register)
6.2.12.1 Page 0 (Port9 GPIO/LCD Segment, Port6 GPIO/LCD Com, LCD Bias,
Scan Key Signal Control Register)
Bit 7
P9SH
Bit 6
P9SL
Bit 5
P6S
Bit 4
BIAS3
Bit 3
BIAS2
Bit 2
BIAS1
Bit 1
0
Bit 0
SC
Bit 0: (SC) Scan key signal.
0: Disable scan key signal
1: Enable scan key signal
Once you enable this bit, all of the LCD signal will have a low pulse during a common
period. This pulse has 30µs width. Use the following procedures to implement the key
scans function:
a) Set Port7 as input port
b) Set IOCD Page 0 Port 7 to pull high
c) Enable scan key signal
d) Once a key is pressed, set RA (6)=1, and switch to normal mode
e) Blank LCD. Disable scan key signal
f) Set P9SL = 0, P9SH = 0. Port 9 sent probe signal to Port 7 and read Port 7 to get
the key.
Note that a probe signal instruction delay will occur before the next instruction is
performed.
g) Set P9SH = 1, P9SL =1. Define Port 9 as LCD signal and enable LCD.
NOTE
This procedure is also applicable to Port 6 and Port 8.
KEY5 KEY1
P93
KEY2
P92
KEY3
P91
KEY4
P90
P73 P72 P71 P70
16 of 36 Mar.01.2005 (V1.1)
Fig. 7 Key Scans Circuit
This specification is subject to change without further notice.
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