HOW to use the timer to generate a interrupter(Cycle variable)

nan li44

Expert 2025 points

i use the GPT0 to generate a interrupter:

void rx_sync(void)

{

uint32_t current_value =0;

current_value = GPTimerCC26XX_getFreeRunValue(h_RFS) & 0x0000FFFF;

switch(fsm_timer)

{
case 0:
current_value += 3000; //next interrupter occur after 3000us
GPTimerCC26XX_setMatchValue(h_RFS, (0x2F0000 | (current_value & 0x0000FFFF)));
fsm_timer =1;
break;

case 1:

current_value += 5000; //next interrupter occur after 5000us
GPTimerCC26XX_setMatchValue(h_RFS, (0x2F0000 | (current_value & 0x0000FFFF)));
fsm_timer =2;
break;

case 2:

current_value += 2000 //next interrupter occur after 2000us
GPTimerCC26XX_setMatchValue(h_RFS, (0x2F0000 | (current_value & 0x0000FFFF)));
fsm_timer =3;
break;

case 3:

current_value += 1000 //next interrupter occur after 1000us
GPTimerCC26XX_setMatchValue(h_RFS, (0x2F0000 | (current_value & 0x0000FFFF)));
fsm_timer =0;
break;
default:break;
}

}
void SYNC_TIMER_callback()
{
rx_sync();
return;
}
void taskRFSFxn(UArg arg0, UArg arg1)
{

GPTimerCC26XX_Params rfsParams;
GPTimerCC26XX_Params_init(&rfsParams);

rfsParams.width = GPT_CONFIG_16BIT;
rfsParams.mode = GPT_MODE_PERIODIC_UP;
rfsParams.debugStallMode = GPTimerCC26XX_DEBUG_STALL_ON;
h_RFS = GPTimerCC26XX_open(RF_SYNC_TIMER, &rfsParams);

if(h_RFS == NULL)
{
while(1);//fail to open the Timer
}
GPTimerCC26XX_setLoadValue(h_RFS, 0x2FFFFF);
GPTimerCC26XX_registerInterrupt(h_RFS, (GPTimerCC26XX_HwiFxn)&SYNC_TIMER_callback,GPT_INT_MATCH);
GPTimerCC26XX_start(h_RFS);
while(1)
{
Task_sleep(BIOS_WAIT_FOREVER);
}

}

i want that when the interrupter occur, i want the next interrupter will come after 3000us/5000us/2000us/1000us ,but result is error, How to do it in the right way？

over 9 years ago

0 Christin Lee over 9 years ago

TI__Guru 56405 points

Hi,

Can you post what kind of error you are getting? Can you try stop the timer in your callback before changing the match value and then start it again?

0 nan li44 over 9 years ago in reply to Christin Lee

Expert 2025 points

Dear Christin,

i toggle the LED pin when the interrupter occur like this:

void SYNC_TIMER_callback()
{
rx_sync();

LEDG_TOGGLE();

return;
}

and i got this:

i try stop the timer in the callback before changing the match value and then start it again, the result is the same.

0 nan li44 over 9 years ago in reply to Christin Lee

Expert 2025 points

Dear Christin,
Can you give me some advice？

LiNan

0 Christin Lee over 9 years ago in reply to nan li44

TI__Guru 56405 points

Hi,

Sorry for the delayed answer.

There are couple of mistakes in your code

1. When the counter reaches the match value. It will start from 0 again, which means you don't need to read current value and add the interval value on top of that.

2. The tick numbers you calculated seem a bit weird.

If you want 3000us, then the tick number should be 3*48000-1. You should not just add 3000 into the current value, or use 3000 as the tick value.

Ad you can see I have no problem achieving this. For more detail regarding our GPTimer module, please take a look at our TRM chapter 13.

0 nan li44 over 9 years ago in reply to Christin Lee

Expert 2025 points

Dear Christin,

could you post your code?

0 Christin Lee over 9 years ago in reply to nan li44

TI__Guru 56405 points

As stated, in the call back function, you don't need to the current tick, which means no need for this line
"current_value = GPTimerCC26XX_getFreeRunValue(h_RFS) & 0x0000FFFF;"
And then you just need to call the GPTimerCC26XX_setMatchValue(timerHandle, correct_tick_value) inside your cases.

There is nothing special that's needed.

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HOW to use the timer to generate a interrupter(Cycle variable)