BLE on CC2640

Hi JXS, could you please expand on MAX_NUM_PDUs and how to use it to send data? What is the actual call to send notifications? Could you please post an example of how to send a notification(s) and if necessary check if more can be sent before losing any packets? What's the max datarate achieved with CC2650 to an Android with 7.5ms connection intervals and 20B/packet? On the Nordic nRF51 I'm able to achieve 85kbps as confirmed by a Frontline BPA LE analyzer. Thank you.

Hi JXS,

I saw the SimpleBLEPeripheral and HeartRate examples and they use notifications to send data upon timer expiration. What I'd like to do is not use the timer, but rather just blast as many notifications as possible in a, for example, a while(true) loop. So would I call GATT_Notification() repeatedly until error? Where would I get a callback so that I can restart the GATT_Notification() calls?

On the Nordic nRF51, I'm getting 85kbps user payload, not raw. What is the max you've gotten on CC2650DK? Is there an example code for this?

Thanks!

Hi Tim,

I don't see a section 5.3.5 in swru393.

Thanks for the OverlappedProcessing wiki, however it's not applicable to me since I want to use a common Android/Apple/Windows device as the master, so it will set the max number of PDUs in the connection interval. Anyhow it's a good starting point and I'd like some clarifications.

In the wiki, it says that 20B are sent every 1ms using a timer. This is obviously slower than the min allowed connection interval of 7.5ms, so multiple packets should be ready for each connection event. But how do you know you've not saturated the number of buffers when calling GATT_Notification()? There's no else for the if statement

if (!(GATT_Notification(0, &noti, FALSE))) //if sucessful

So what should we do if this fails? Is the number of buffers MAX_NUM_PDU, which is 10 in bleUserConfig.h?

In my system, 60B of data will be ready for transmission every 50ms. How can I implement data transmission without using a timer to send 3x 20B every 1ms after the interrupt? Do I simply call GATT_Notification() three times in a row with the correctly allocated data (three GATT_bm_alloc() calls)? 

Thanks!

I did some testing on HeartRate_measNotify() and used the else of

if (!(GATT_Notification(0, &noti, FALSE))) //if sucessful

to update the values to be sent in the notification. This matches the overlapped processing example where you update the value if successful transmission, otherwise wait until the next call of  HeartRate_measNotify(). The HeartRate_measNotify() function already deallocates the GATT_bm_alloc() if the transmission is not successful, so I think this solution should work fine.

Another thing I did was instead of using a timer that expires every 1ms to send 20B, I instead posted the semaphore with the HEARTRATE_MEAS_PERIODIC_EVT set. So instead of using a timer to call Gatt_Notification(), I did the following:

static void HeartRate_taskFxn(UArg a0, UArg a1)
{
  // Initialize the application.
  HeartRate_init();
  
  // Application main loop.
  for(;;)
  {
...    
    // Heart rate service periodic task.
    if (gHRNotifyEnabled && events & HEARTRATE_MEAS_PERIODIC_EVT)
    {
      events &= ~HEARTRATE_MEAS_PERIODIC_EVT;
      
      HeartRate_measPerTask();
    }
    
...
  }
}

static void HeartRate_measPerTask(void)
{
  if (gapProfileState == GAPROLE_CONNECTED)
  {
    // Send heart rate measurement notification.
    HeartRate_measNotify();
    
    // Restart timer.
//    Util_startClock(&measPerClock);
    events |= HEARTRATE_MEAS_PERIODIC_EVT;
    Semaphore_post(sem);
  }
}

static void HeartRate_heartRateEvt(uint8_t event)
{
  if (event == HEARTRATE_MEAS_NOTI_ENABLED)
  {
    // If connected start periodic measurement.
    if (gapProfileState == GAPROLE_CONNECTED)
    {
//      Util_startClock(&measPerClock);
    	gHRNotifyEnabled = 1;
    	events |= HEARTRATE_MEAS_PERIODIC_EVT;
    	Semaphore_post(sem);
    }
  }
  else if (event == HEARTRATE_MEAS_NOTI_DISABLED)
  {
    // Stop periodic measurement.
//    Util_stopClock(&measPerClock);
	  gHRNotifyEnabled = 0;
  }
...
}

Are there any benefits to using the 1ms timer versus what I'm doing? Both methods stream 85kbps data to an Asus Nexus 7, which is what I expect.

Yep, I was looking at SDG v2.0; v2.1 has section 5.3.5 :)

Thanks for the wiki. In your wiki, you don't post the semaphore after each loop in blastData(), but rather just use a while(1). Is there a drawback/benefit to posting the semaphore, or should I do it as you have done? I suppose the throughput would be slower, but I connecting to an Android device which has a limited number of connection events per connection interval. Also, does Android/iOS support ATT_MTU=255, or are they limited to 23? Thanks!

Thanks for your help Tim. I think this is working fine now. FYI the SDG link goes to v2.0; I got v2.1 in the c:\ti install directory.