AN2120: Connecting an M68HC08 Family Microcontroller to an ...

Application Note
Desc : It sets the modem response mode to numeric (instead of verbose),
then it dials a phone number & sets the DTR pin. This function
returns a numeric code describing a response from the modem or
a timeout. Applications should handle this reaponse code.
***********************************************************************/
BYTE ModemDial (char * Number) {
signed char delayCount = 80;
transmit ("ATV0\r"); // Force a numeric response from modem
if (!Waitfor ("0", 30)) { // Wait for an OK response
return -1;
}
}
DTR_ON; // Set DTR to ON
transmit ("ATDT"); // Dial the ISP number
transmit (Number);
transmit ("\r");
ModemBuffFlush (); // Flush contents of buffer
// Wait for a reply
while ((!ModemBuffNotEmpty()) && (--delayCount > 0)) {
Delay (250);
}
if (delayCount) {
return ModemGetch (); // Return the numeric response to caller
}
return -1; // No response received from modem
/***********************************************************************
Function : ModemHangUp
Parameters : None
Date : December 2000
Desc : This function clears DTR to force the modem to hang up if
it was on line and/or make the modem to go to command mode.
***********************************************************************/
void ModemHangUp (void) {
DTR_ON; // Make a DTR transition to hang-up
Delay (40); // Wait a couple of miliSeconds
DTR_OFF; // Finish the DTR transition
}
AN2120
74 MOTOROLA