Hitachi H8/3637 Hardware Manual page 279

Bits 3 and 2—DTMF Column Signal Output Frequency 1 and 0 (CLF1, CLF0): Bits 3 and 2
select the DTMF column signal frequency (C1 to C4).
Bit 3: CLF1 Bit 2: CLF0
0 0
1
1 0
1
Bits 1 and 0—DTMF Row Signal Output Frequency 1 and 0 (RWF1, RWF0): Bits 1 and 0
select the DTMF row signal frequency (R1 to R4).
Bit 1: RWF1 Bit 0: RWF0
0 0
1
1 0
1
Description
DTMF column signal output frequency: 1209 Hz (C1)
DTMF column signal output frequency: 1336 Hz (C2)
DTMF column signal output frequency: 1447 Hz (C3)
DTMF column signal output frequency: 1633 Hz (C4)
Description
DTMF row signal output frequency: 697 Hz (R1)
DTMF row signal output frequency: 770 Hz (R2)
DTMF row signal output frequency: 852 Hz (R3)
DTMF row signal output frequency: 941 Hz (R4)
(initial value)
(initial value)
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