HOLTEK 9200B & 9170B DTMF Generator & Receiver

Posted on Feb 5, 2014

The 4 data lines from the Keypad Interface go straight into the data inputs of the Holtek 9200B DTMF Generator (pins 6, 7, 8 & 9), and the Inverted Chip Enable output on the Keypad Interface goes into the Chip Enable Input on the Holtek 9200B DTMF Generator (pin1). When the Chip Enable line is at logic 0, a DTMF tone is generated from the DTMF out

HOLTEK 9200B & 9170B DTMF Generator & Receiver
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put (pin 13) with respect to ground. This is an `Active Low` input so logic 0 will enable the chip. The DTMF output is then taken to the DTMF input line of the Holtek 9170B DTMF Receiver. When a tone is present, the Data Valid output goes high (pin 15). Also the DTMF tone will be decoded to a 4 bit binary number on the output lines (pins 11, 12, 13 and 14).

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