W921E400A Datasheet, PDF (21/53 Pages) Winbond – 4-BIT MICROCONTROLLER

W921E400A/W921C400
There are four bits in the DTMF register; the functions are described in the following table:
DTMF register: (address = 014H, default data = 0H)
b3 b2 b1 b0
XX00
XX01
XX10
XX11
00XX
01XX
10XX
11XX
Note : X Ä don't care
Function Description
Column 1 ( 1209 Hz ) output
Column 2 ( 1336 Hz ) output
Column 3 ( 1477 Hz ) output
Column 4 ( 1633 Hz ) output
Row 1 ( 697 Hz ) output
Row 2 ( 770 Hz ) output
Row 3 ( 852 Hz ) output
Row 4 ( 941 Hz ) output
The output frequency of the row and column will be controlled by the row/column frequency control
register (RCCTL).
RCCTL register: (address = 015H, default data = 0H)
b3
b2
b1
b0
Reserved
0: Row frequency disable
1: Row frequency enable
0: Column frequency disable
1: Column frequency enable
0: DTMF disable (H-Z)
1: DTMF enable
The following table shows the DTMF keypad and its frequency.
C1 C2 C3 C4
1 2 3 A R1
4 5 6 B R2
7 8 9 C R3
* 0 # D R4
Key Frequency
R1
697 Hz
R2
770 Hz
R3
852 Hz
R4
941 Hz
C1 1209 Hz
C2 1336 Hz
C3 1477 Hz
C4 1633 Hz
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Publication Release Date: July 1999
Revision A3