
LC7464M
No.3588–4/7
Output Data Configuration
The 48-bit output data configuration is shown in the
following figure. Note that the data is sent least-signifi-
cant bit first.
Custom code
The 16-bit mask-programmable custom code (C0 to C15)
is a unique code registered with the Association for
Electric Home Appliances.
Parity bits
The four parity bits (P0 to P3) are used for error detec-
tion. Their value is given by the following equation.
Pn=Cn
⊕ C(n+4) ⊕ C(n+8) ⊕ C(n+12)
where n=0 to 3.
System code
The four-bit system code (SC0 to SC3) is mask-pro-
grammed into the LC7464M during fabrication.
Product code
The eight-bit product code (GC0 to GC7) consists of two
mask-programmable bits and six bits that are set by
connecting each of GCL and GCH to one of KO0 to
KO7. The block diagram of the product code generator is
shown in the following figure. GC1 and GC3 are the
mask-programmable bits, shown set to zero.
C0 to C15
16-bit custom code
4-bit parity
4-bit system code
8-bit product code
8-bit function code
8-bit data check code
P0 to P3
SC0 to SC3
GC0 to GC7
FC0 to FC7
DC0 to DC7
Functional Description
Key Inputs
An eight-by-eight matrix is formed with the keyswitch
scanning outputs KO0 to KO7 and the keyswitch scan-
ning inputs KI0 to KI7 as shown in the following figure.
When a key is held down, either the normal or abbrevi-
ated continuation code is output continously, depending
on the mask option selected.
Normally, only one key can be pressed at a time. If more
than one key is pressed, all keys are ignored and no
output is generated. However, when the appropriate mask
option is selected, up to three extra codes can be gener-
ated by holding down key 8 and either key 16, 24, 32, 40,
48, 56 or 64 as shown in table 1.
n
o
i
t
a
n
i
b
m
o
c
y
e
K
e
d
o
c
n
o
i
t
c
n
u
F
0
C
F1
C
F2
C
F3
C
F4
C
F5
C
F6
C
F7
C
F
6
1
,
8
11101001
4
2
,
8
11100101
2
3
,
8
11101101
0
4
,
8
11100011
8
4
,
8
11101011
6
5
,
8
11100111
4
6
,
8
11101111
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
KI0 KI1 KI2 KI3 KI4 KI5 KI6 KI7
KO0
KO1
KO2
KO3
KO4
KO5
KO6
KO7
Table 1. Function code generation