Repeaters: 146.700- Mhz | 146.970- Mhz | 443.700+ Mhz | 445.075- Mhz | PL: 100 hz

10 Minutes ID Reminder for $4.30

FCC regulations (Part 97.119) require callsign identification at the end of a contact and at least once every ten (10) minutes during a contact. Sometimes it is difficult to keep track of this requirements putting us in risk of violating this FCC regulation.

So, I decided to do something about it..

A few years ago Texas Instruments made available a developing and evaluation board to showcase their MSP430 family of micro controllers. The evaluation board is called LaunchPad and it is being adopted by many thinkerer’s and DIYfers due to its low price ($4.30) and flexibility.

This board allows you to program your code and interact with inputs and produce outputs at will. The programming is done via an USB port. The Integrated Development Environment or (IDE) is also available for free from TI. Once you write your code and successfully compile it you can upload this code and have the micro controller run it.

The MSP430 incorporated with the LaunchPad has many neat features such as analog to digital converters, timers, comparator, temperature sensor, low power consumption, etc. The PCB board has a build in button and 2 LED’s. I took advantage of this I/O and wrote the following code:

#include "io430.h"
void delay_ms(unsigned int ms ){ 		
      unsigned int i;
      for (i = 0; i <= ms; i++){ 		
void t_led( int led, int delay ) {
	P1OUT ^= led;
	delay_ms( delay );
void main(void) {
  P1DIR |= BIT0 + BIT6;         	
  int count = 0; 
  int min = 0;
  int tot = 9;
  while(1) {
   while ((min < tot) && ((P1IN & BIT3))){
    P1OUT &= ~BIT0;
    while ((count < 60) && ((P1IN & BIT3))){
     if (min < (tot-1)){
     else {
   count = 0;
  if (!(P1IN & BIT3)){
   P1OUT &= ~BIT0;
   count = 0;
   min = 0;

To download the IAR Workspace complete project click here.

The source code above makes the GREEN LED blink at a slow rate the first 9 minutes. The last minute the GREEN LED blinks a little faster to indicate that it is about time to ID and at the 10 minute mark it blinks the RED LED indicating that you went over. The RED LED blinks until the button is pressed and it resets the timer. If the button is pressed midway the countdown the timer is also reset.

The LaunchPad does not need to be connected to a computer to function, it has a header pin that allows you to connect a battery or external power supply to it.

Feel free to use, modify and improve the code. If you have any questions or comments feel free to post it on the comments section bellow.

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2 thoughts on “10 Minutes ID Reminder for $4.30”

  1. Hello,
    Saw another Johnstown on echolink and thought I’d check it out. I’m in the one in PA which is usually just known for our floods! I like your id timer, if I were using my radios I’d get one. I’m not sure if that’s made to use on pc or just radio.
    Have a great day!
    Br. Solanus m.i.m. aka Barry

  2. Hello Barry,

    At least Johnstown PA is know for something ;). The project above is used to provide visual feedback to remind the operator to ID. It can be used for other things of course. The code can be modify to change the time interval to whatever you want.

    Thanks for stopping by.

    Edgar / KC2UEZ

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