JCM J3500E, Руководство по обслуживанию

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7
KR0
1
KR1
2
KR2
3
KR3
4
KR4
5
CN13
W-D0805#01
KS0
1
KS1
2
KS2
3
KS3
4
KS4
5
KS5
6
KS6
7
KS7
8
KS8
9
CN15
W-D0809#01
COM
1
REG
2
X
3
Z
4
P
5
SP
6
CN14
5267-06A
KS[0..3]
KEY SCAN
KEY RETURN
CONTROL
A
1
B
2
C
3
G1
6
G2A
4
G2B
5
Y0
15
Y1
14
Y2
13
Y3
12
Y4
11
Y5
10
Y6
9
Y7
7
U22
SN74LV138APWR
A
1
B
2
C
3
G1
6
G2A
4
G2B
5
Y0
15
Y1
14
Y2
13
Y3
12
Y4
11
Y5
10
Y6
9
Y7
7
U21
SN74LV138APWR
D23 1SS355
D14 1SS355
D20 1SS355
D15 1SS355
D21 1SS355
D16 1SS355
D22 1SS355
D17 1SS355
D18 1SS355
D19 1SS355
VCC
FB75 BLM21AG121SN1
FB76 BLM21AG121SN1
FB77 BLM21AG121SN1
FB78 BLM21AG121SN1
FB79 BLM21AG121SN1
FB80 BLM21AG121SN1
FB81 BLM21AG121SN1
FB82 BLM21AG121SN1
FB83 BLM21AG121SN1
FB64 BLM21AG121SN1
FB66 BLM21AG121SN1
FB68 BLM21AG121SN1
FB70 BLM21AG121SN1
FB72 BLM21AG121SN1
FB74 BLM21AG121SN1
FB65 BLM21AG121SN1
FB67 BLM21AG121SN1
FB69 BLM21AG121SN1
FB71 BLM21AG121SN1
FB73 BLM21AG121SN1
1 2
4 3
DSW1
KSD-02
D13
1SS355 D12
1SS355
R68
473 R66
473 R69
473 R67
473 R64
473 C77
101C C75
101C C78
101C C76
101C C74
101C
KS0
KS1
KS2
KS3
KR[0..4]
KR[0..4]
KR0
KR1
KR2
KR3
KR4
VCC VCC VCC VCC VCC
2 3 4
5
7 8 9 1
10
6
RA6
RA104
VCC VCC
R63
104 R65
104
VCC VCC
KS[0..3]
3.2.3 KEY BOARD CIRCUIT
Input and output signal for key board scanning are passing through CN13~CN15.
The output signals from output port (P140-P143) of U11 are encoded signals.
By passing through U21,U22(74HC138), they are decoded to key scan signals. And they are
applied to key matrix via CN15.
When a certain key is depressed, one of decoded signal is applied to U11(MPU) via CN13.
Thus U11(MPU) recognizes which key is depressed and executes key’s specific operation.
The scanning signal from U26 –Y1 scans control lines KR0-KR4 and they are applied to
U11(MPU) as control signals.
According to the status of control signals, U11(MPU) executes specific operation.
Scan signal
MPU
Data bus
Fig 3-1 key board circuit
Timing chart of key scan signals
P140
P141
P142
P143
Y0
Y1
Y2
Y7
5.48msec