CCS/CC2640R2F: GPTimerCC26XX with GPT_MODE_EDGE_COUNT

Toni Lahnalampi

Prodigy 70 points

Part Number: CC2640R2F
Other Parts Discussed in Thread: SYSBIOS

Tool/software: Code Composer Studio

Hi,

We are trying to implement pulse counter for rotary encoder with GPTimerCC26XX.h.

timerCallback is working, when we use timerParams.mode = GPT_MODE_EDGE_TIME, but not with GPT_MODE_EDGE_COUNT.

Could anyone explain why it does not work?

void timerCallback(GPTimerCC26XX_Handle handle,
                   GPTimerCC26XX_IntMask interruptMask) {
  Log_info0("interrupt");
}

PIN_Config GptPinInitTable[] = {
  PIN_ID(Board_ENCODER) | PIN_INPUT_EN | PIN_PULLUP | PIN_HYSTERESIS, 
  PIN_TERMINATE
};

static void ProjectZero_init(void)
{

  ...

  GPTimerCC26XX_Params timerParams;
  GPTimerCC26XX_Handle hTimer;
  GPTimerCC26XX_Params_init(&timerParams);
  timerParams.mode = GPT_MODE_EDGE_COUNT;
  timerParams.width = GPT_CONFIG_16BIT;
  
  hTimer = GPTimerCC26XX_open(CC2640R2_LAUNCHXL_GPTIMER0A, &timerParams);
  
  // Register interrupt when capture happens
  GPTimerCC26XX_registerInterrupt(hTimer, timerCallback, GPT_INT_CAPTURE);
  
  // Open pin handle and route pin to timer
  timerPinHandle = PIN_open(&timerPinState, GptPinInitTable);
  GPTimerCC26XX_PinMux pinMux = GPTimerCC26XX_getPinMux(hTimer);
  PINCC26XX_setMux(timerPinHandle, PIN_ID(Board_ENCODER), pinMux);
  GPTimerCC26XX_setCaptureEdge(hTimer, GPTimerCC26XX_BOTH_EDGES);
  GPTimerCC26XX_setLoadValue(hTimer, 0x0000);
  GPTimerCC26XX_setMatchValue(hTimer, 0x0010);
  
  GPTimerCC26XX_start(hTimer);
}

over 6 years ago

0 Toni Lahnalampi over 6 years ago

Prodigy 70 points

I found out, that someone had a similar problem:

https://e2e.ti.com/support/tools/ccs/f/81/t/801871

And I also read Timers section from CC13x0, CC26x0 SimpleLink™ Wireless MCU Technical Reference Manual

Now my edge counter started to work, but I still don't understand, why I need to set load value to 0xFFFF. If I set it to 0x0000 it does not work.

Now I have same problem as him, that I need to reset load value. I tried using GPTimerCC26XX_setLoadValue(hTimer, 0xFFFF) but it did not have any effect.

And GPTimerCC26XX.h says, that if I need high accuracy, I need to setDepencency:

#include <ti/sysbios/family/arm/cc26xx/Power.h>
#include <ti/sysbios/family/arm/cc26xx/PowerCC2650.h>
Power_setDependency(XOSC_HF);

It seems, this code does not work with simplelink SDK 3.10.00.15. How it should be implemented with this SDK?

0 Toni Lahnalampi over 6 years ago in reply to Toni Lahnalampi

Prodigy 70 points

And now I found out, that someone had also solved, how to reset GPTimer value register:

https://e2e.ti.com/support/wireless-connectivity/bluetooth/f/538/t/722625

#define GPT_0_OFFSET 0
GPTimerCC26XX_Handle hTimer;

void timerCallback(GPTimerCC26XX_Handle handle,
                   GPTimerCC26XX_IntMask interruptMask) {
  uint32_t edgeCount = GPTimerCC26XX_getValue(handle);
  Log_info1("callback %u", edgeCount);
}

PIN_Config gptPinInitTable[] = {
  Board_ENCODER | PIN_INPUT_EN | PIN_PULLUP | PIN_HYSTERESIS,   
  PIN_TERMINATE
};

static void ProjectZero_init(void)
{

  ...

  GPTimerCC26XX_Params timerParams;
  GPTimerCC26XX_Handle hTimer;
  GPTimerCC26XX_Params_init(&timerParams);
  timerParams.mode = GPT_MODE_EDGE_COUNT;
  timerParams.width = GPT_CONFIG_16BIT;
  timerParams.direction = GPTimerCC26XX_DIRECTION_UP;
  
  hTimer = GPTimerCC26XX_open(CC2640R2_LAUNCHXL_GPTIMER0A, &timerParams);
  
  // Register interrupt when capture happens
  // GPT_MODE_EDGE_COUNT seems to trigger GPT_INT_CAPTURE_MATCH interrupts
  GPTimerCC26XX_registerInterrupt(hTimer, timerCallback, GPT_INT_CAPTURE_MATCH);
  
  // Open pin handle and route pin to timer
  timerPinHandle = PIN_open(&timerPinState, gptPinInitTable);
  GPTimerCC26XX_PinMux pinMux = GPTimerCC26XX_getPinMux(hTimer);
  PINCC26XX_setMux(timerPinHandle, PIN_ID(Board_ENCODER), pinMux);
  GPTimerCC26XX_setCaptureEdge(hTimer, GPTimerCC26XX_BOTH_EDGES);

  // When counting in upwads direction LoadValue needs to be at least as 
  // large as matchValue for interrupts to work.
  GPTimerCC26XX_setLoadValue(hTimer, 0xFFFF); 
  GPTimerCC26XX_setMatchValue(hTimer, 1000);
  
  GPTimerCC26XX_start(hTimer);
}

static void user_handleButtonPress(button_state_t *pState) {
  switch (pState->pinId) {
    case Board_PIN_BUTTON0:
        if (pState->state) { // button pressed
          uint32_t edgeCount = GPTimerCC26XX_getValue(hTimer);
          Log_info1("button pressed %u", edgeCount);
        } else { // button released
          uint32_t edgeCount = GPTimerCC26XX_getValue(hTimer);
          Log_info1("button released %u", edgeCount);

          //-------------------------------------------------------------
          // Reset GPTimer0 value register
          //-------------------------------------------------------------
          HWREG(hTimer->hwAttrs->baseAddr + GPT_0_OFFSET + GPT_O_TAV) = 0;

        }
    break;
  }
}

0 Alexis Crandall20 over 6 years ago in reply to Toni Lahnalampi

TI__Genius 15590 points

Hi Toni,

I'm glad you were able to resolve your issue. Thanks for sharing!

BR,

Alexis

Bluetooth®︎

Bluetooth forum

CCS/CC2640R2F: GPTimerCC26XX with GPT_MODE_EDGE_COUNT