Sharp ER-A520 Service Manual page 13

6-2. KEY/DISPLAY SCAN
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: Read before 10~100us of strobe signal
OFF.
Key/Display-related Register
Function
LED Segment Signal
<LED Segment Signal> Write
Address Bit7 Bit6 Bit5
100000h DP g f
<CPU PORT>
Signal to
No. CPU PORT
be used
131 P150 KS0
129 P151 KS1
128 P152 KS2
127 P153 KS3
126 P154 LS0
125 P155 LS1
124 P156 LS2
123 P157 LS3
KS3~0 : KEY strobe signal is generated.
LS3~0 : POP UP Display strobe signal is generated.
Signal to
No. CPU PORT
be used
46 P70 KR0#
45 P71 KR1#
44 P72 KR2#
43 P73 KR3#
42 P74 KR4#
41 P75 KR5#
40 P76 KR6#
39 P77 KR7#
14 P140 KR8#
13 P141 KR9#
R0#~KR9# : Flat Keyboard KEY Return signal
KR0#~KR7# : Normal Keyboard KEY Return signal
Address R/W
100000h W
Bit4 Bit3 Bit2 Bit1
e d c B
Function
KEY STROBE SIGNAL 0
KEY STROBE SIGNAL 1
KEY STROBE SIGNAL 2
KEY STROBE SIGNAL 3
LED STROBE SIGNAL 0
LED STROBE SIGNAL 1
LED STROBE SIGNAL 2
LED STROBE SIGNAL 3
Function
KEY RETURN SIGNAL 0
KEY RETURN SIGNAL 1
KEY RETURN SIGNAL 2
KEY RETURN SIGNAL 3
KEY RETURN SIGNAL 4
KEY RETURN SIGNAL 5
KEY RETURN SIGNAL 6
KEY RETURN SIGNAL 7
KEY RETURN SIGNAL 8
KEY RETURN SIGNAL 9
KS0 - 3
0h
(0h~Fh repeat)
Key Return Sinnal
950 25us
LS0 - 3
0h
(0h~9h repeat)
Max.10us
LED Segment
1ST DIGIT
DISPLAY DATA
Signal
ER-A520U/ER-A530U HARDWARE DESCRIPTION
Bit0
a
No. CPU PORT
12 P142
11 P143
The mode key switch and other signals are read at CPU ports P142 and
P143 at the key strobe timing.
Reading is made 10~100us before the strobe signal OFF..
P142 ST0 : MODE Key SRV
ST1 : MODE Key PGM
ST2 : MODE Key VOID
ST3 : MODE Key OP X/Z
ST4 : MODE Key REG
ST5 : MODE Key MGR
ST6 : MODE Key X1/Z1
ST7 : MODE Key X2/Z2
P143 ST10 : Receipt feed
ST11: Journal feed
ST13 : Keypad select
The Flat Keyboard takes key data in twice during the strobe period.
For read timing, refer to the timing chart below.
588us ±20us
1h 2h
10 - 100us
50 10us
Fh 1h Fh
2nd DIGIT
DISPLAY DATA
BLANK BLANK
– 12 –
Signal to
Function
be used
MODE# MODE KEY SIGNAL
FSR# FEED SENS SIGNAL
"0" SRV mode
"0" PGM mode
"0" VOID mode
"0" OP X/Z mode
"0" REG mode
"0" MGR mode
"0" X1/Z1 mode
"0" X2/Z2 mode
"0" Receipt feed
"0" Journal feed
"1" Flat key
"1" JNormal key
Fh
Fh
9h
1ST DIGIT
DISPLAY DATA
BLANK
0h
0h