Table 1: Digits vs. input data vs. tone output frequency (serial mode)

Digit

D4

D3

D2

D1

D0

Tone Output Frequency (Hz)

10

0

0

0

1

697

+1209

20

0

0

1

0

697

+1336

30

0

0

1

1

697

+1477

40

0

1

0

0

770

+1209

50

0

1

0

1

770

+1336

60

0

1

1

0

770

+1477

70

0

1

1

1

852

+1209

80

1

0

0

0

852

+1336

90

1

0

0

1

852

+1477

00

1

0

1

0

941

+1336

∗

01

0

1

1

941

+1209

#

01

1

0

0

941

+1477

A0

1

1

0

1

697

+1633

B0

1

1

1

0

770

+1633

C0

1

1

1

1

852

+1633

D0

0

0

0

0

941

+1633

—1

0

0

0

0

697

—1

0

0

0

1

770

—1

0

0

1

0

852

—1

0

0

1

1

941

—1

0

1

0

0

1209

—1

0

1

0

1

1336

—1

0

1

1

0

1477

—1

0

1

1

1

1633

DTMF OFF

1

1

1

1

1

—

*Notes: The codes not listed in Table 1 are not used D4 is MSB

Functional Description

The HT9200A/B are DTMF generators for

µC

interfaces. They are controlled by a

µC in the

serial mode or the parallel mode (for the

HT9200B only).

Serial mode (HT9200A/B)

The HT9200A/B employ a data input, a 5-bit

code, and a synchronous clock to transmit a

DTMF signal. Every digit of a phone number to

be transmitted is selected by a series of inputs

which consist of 5-bit data. Of the 5 bits, the

D0(LSB) is the first received bit. The

HT9200A/B will latch data on the falling edge of

the clock (CLK pin). The relationship between

the digital codes and the tone output frequency

is shown in Table 1. As for the control timing

diagram, refer to Figure 1.

HT9200A/B