HI Rob Redding

Thanks for the code.

Okey now the very issue i am facing reviewing you code is how the DTMF tune is produced on the pin of the microcontroller. Here is the main() of your program. In the loop

printf("%dn", next_dtmf_sample());

and the function next_dtmf_sample() returns unsigned short. please explain that how this statement produce DTMF on the pin of the microcontroller.

Thanks
Shahzad


main(void)
{
int i;
printf("Waveform sample set for DTMF Digit 1.n");
printf("Redirect output to a file and graph to view waveform.n");


/* Initialize DTMF generator for Digit 1 output. */
new_tone(DTMF_1);

/* Assuming a sample rate of 10 kHz, issue 100 ms of tone samples */
for (i = 0; i < 1000; i++)
{
printf("%dn", next_dtmf_sample());
}

exit(0);
}