Hi,

I am using 80C51 with crystal 11.0592Mhz, an external oscillator for 100 Khz generation of CLK to DTMF transmitter HT9200A


I dialled no 30.

I used DTMF output interface circuit as mentioned in Holted forum

Problem is some times it dials & sometimes it doesnot work.. Please find any bug in the code

or suggest me to how dial correctly

void main(void)
{
TMOD=0x01;
TL0=0xB2; // TL0 Reload value
TH0=0xFE; // TH0 Reload value 1 Khz
ET0=1;
TR0=1; // Start Timer0
EA=1;
P0_1 = 0; // 100KHz CLK started from external 555 timer
dial();
while(1)
{
}


}


void timer0() interrupt 1 // interrupt address is 0x000b
{

TF0 = 0; // reset interrupt flag
TL0=0xB2; // TL0 Reload value
TH0=0xFe; // TH0 Reload value 1 Khz


}

void dial()

{


P0_0 = 0; // CE Enable Chip
delay(9216); // Delay for 10ms after CE selected



P0_2 = 1; // D0
P0_2 = 1; // D1
P0_2 = 0; // D2 Send Digit 3
P0_2 = 0; // D3
P0_2 = 0; // D4

P0_1 = 1; // CLK off
delay(5000);
P0_1 = 0; // CLK ON

P0_2 = 1; // D0
P0_2 = 1; // D1
P0_2 = 1; // D2 Stop DTMF
P0_2 = 1; // D3
P0_2 = 1; // D4 */

P0_1 = 1; // CLK off
delay(5000);
P0_1 = 0; // CLK ON



P0_2 = 0; // D0
P0_2 = 1; // D1 // Send Digit 0
P0_2 = 0; // D2
P0_2 = 1; // D3
P0_2 = 0; // D4


P0_1 = 1; // CLK off
delay(5000);
P0_1 = 0; // CLK ON

P0_2 = 1; // D0
P0_2 = 1; // D1
P0_2 = 1; // D2 Stop DTMF
P0_2 = 1; // D3
P0_2 = 1; // D4

}

Thanks Please help me