W742S81A Datasheet, PDF (30/47 Pages) Winbond – 4 BIT MICROCONTROLLER

W742S81A
6.18.1 Port Status Register 0 (PSR0)
Port status register 0 is organized as 4-bit binary register (PSR0.0 to PSR0.3). PSR0 can be read or cleared
by the MOVA R, PSR0, and CLR PSR0 instructions. The bit descriptions are as follows:
3
2
1
0
PSR0 R
R
R
R
Note: R means read only.
Bit 0 = 1
Bit 1 = 1
Bit 2 = 1
Bit 3 = 1
Signal change at RC.0
Signal change at RC.1
Signal change at RC.2
Signal change at RC.3
6.19 Output Port RE & RF
Output port RE is used as an output of the internal RT port. When the MOV RE, R instruction is executed,
the data in the RAM will be output to port RT through port RE. It provides a high sink current to drive an
LED. RF port is just used as a output port. When the MOV RF, R instruction is executed, the data in the
RAM will be output to RF.
6.20 DTMF Output Pin (DTMF)
This pin should output the dual tone multi-frequency signal from the DTMF generator. There is the DTMF
register that can specify the wanted low/high frequency. And control whether the dual tone will be output
or not. The tones are divided into two groups (Row group and Col group) and one tone from each group is
selected to represent a digit. The relation between the DTMF signal and the corresponding touch tone
keypad is shown in Figure 6-13.
C1 ^{C2 C3 C4}
R1 1 2 3 A
R2 4 5 6 B
R3 7 8 9 C
R4 _* 0 # D
- 30 -
Row/Col
R1
R2
R3
R4
C1
C2
C3
C4
Frequency
697 Hz
770 Hz
852 Hz
941 Hz
1209 Hz
1336 Hz
1477 Hz
1633 Hz