Table 2: Digits vs. input data vs. tone output frequency (parallel mode)

Digit

D3

D2

D1

D0

Tone Output Frequency (Hz)

10

0

0

1

697

20

0

1

0

697

30

0

1

1

697

40

1

0

0

770

50

1

0

1

770

60

1

1

0

770

70

1

1

1

852

81

0

0

0

852

When the system is operating in the serial mode

a pull-high resistor is attached to D0~D3 (for

parallel mode) on the input terminal.

For the HT9200B, the S/P pin has to be connected

low for serial mode operation.

Parallel mode ( HT9200B)

The HT9200B provides four data inputs D0~D3

to generate their corresponding DTMF signals.

The S/P has to be connected high to select the

parallel operation mode. Then the input data

codes should be determined. Finally, the CE is

connected low to transmit the DTMF signal

from the DTMF pin.

CE falling edge to the DTMF signal output.

The relationship between the digital codes and

the tone output frequency is illustrated in Table 2.

As for the control timing diagram, see Figure 2.

When the system is operating in the parallel

mode, D0~D3 are all in the floating state. Thus,

these data input pins should not float.

Figure 1

HT9200A/B

6

21st Aug ’98