Sharp ER-A410 Service Manual page 13

6. KEY/DISPLAY
6-1. LCD CONTROL
The LCD control is the same as that of the ER-A275P.
LCD-related Register
Function
LCD Write Data
LCD Read Data
LCD Control Signal / Key Strobe Signal
Data Latch Signal
<LCD Control Signal/Key Strobe Signal>
Address Bit7 Bit6 Bit5
04003h – E R/W
Bit7: Not used
Bit6: E
Enable Signal
Bit5: R/W
H: Data read L: Data Write
Bit4: RS
H: Data input L: Instruction Input
<Data Latch Signal> P94
L: LCD write data latch
DATA IT (CPU CD
DB0-7
P94
400 4001 400
000 DATA 010
IT IT IT
DATA AD (CPU 1 CD
DB0-7
P94
4003h CPU 4003h
001xxxxx P94 011xxxxx
IT I IT
Address R/W
04001h W
04002h R
04003h W
CPU port P94 W
Bit4 Bit3 Bit2 Bit1
RS KS3 KS2 KS1
Enable
Valid Data
400 400
000 001
IT IT
Valid Data
400 h 4003h CPU 4003h
DATA 001xxxxx P94 001xxxxx
AD IT IT
ER-A410/ER-A420 HARDWARE DESCRIPTION
6-2. KEY/DISPLAY SCAN
On A410/420, the key and display scan signal is common.
Key/display scan and key read are performed at the following timing.
1 Key/display scan cycle: 10ms
2 Blanking time: 50us
3 KEY DATA READ timing: 10 ~100us before turning off the strobe
signal
KEY DATA are read in two divisions by switching the exchange sig-
nal.
Key/Display-related Register
Function
LED Segment Signal
LCD Control Signal / Key Strobe Signal
Bit0
Key Return Signal
KS0
Key Exchange Signal
Key Select Signal
<LED Segment Signal> Write
Address Bit7 Bit6
04000h dp
<LCD Control Signal/Key Strobe Signal> Write
Address Bit7
04003h X
Bit3~0: KS3~0
At KS3~0, the strobe signals of KEY and POP UP Display are gener-
ated.
<Key Return Signal, Key Exchange Signal> Read Flat Keyboard
Address Bit7 Bit6
04001h X
04003h KR7 KR6
<Key Return Signal> Read Normal Keyboard
Address Bit7
04003h KR7 KR6
<Key Select Signal>
READ is performed at the timing of ST9 of CPU port P90 (Refer to 6-3.)
1: NORMAL KEY
0: FLAT KEY
The flat keyboard switches the key exchange signal and takes key data
in two times. For the reading timing, refer to the timing chart below.
The normal keyboard reads key data 10~100us before turning off the
strobe signal of the keyboard.
950
K 0
0
Max. 10
L
1
a
LA
K
a
– 11 –
Address
04000h
04003h
04003h
04003h Bit7
CPU port P90
Bit5 Bit4 Bit3 Bit2
g f e d c
Bit6 Bit5 Bit4 Bit3 Bit2
E R/W RS KS3 KS2
Bit5 Bit4 Bit3 Bit2
X X X KR11 KR10
KR5 KR4 KR3 KR2
Bit6 Bit5 Bit4 Bit3 Bit2
KR5 KR4 KR3 KR2
5 50 5
1 9
N
BLANK BLANK
A A LA A A
10 100
R/W
W
W
R
W
R
Bit1 Bit0
B a
Bit1 Bit0
KS1 KS0
Bit1 Bit0
KR9 KR8
KR1 KR0
Bit1 Bit0
KR1 KR0
0
1
BLANK
LA A A