RE: Loss of notifications when sending them from peripheral to central as bulk transfer

Muhammad Akram Karimi — Wed, 03 Apr 2019 14:32:33 GMT

Oh, what an obvious mistake I made.

Thanks Edvin for the correction. The issue has been resolved with the following implementation of the code.

uint32_t temp_data_burst_xfer(uint32_t* read_buffer_temp)
{
	 static uint8_t cnt = 0;			//Counting the chunks transfered 
   uint32_t        err_code;
	
	while (cnt < TTL_CHUNKS_TEMP && burst_xfer_process)
  {
        err_code =  Burst_characteristic_update(&m_our_service, read_buffer_temp, cnt);		//Sending 20 bytes [cnt represents which block]
				if(err_code == NRF_SUCCESS)
				{
					cnt++;
				}
				else if (err_code == BLE_ERROR_NO_TX_PACKETS ||
            err_code == NRF_ERROR_INVALID_STATE || 
            err_code == BLE_ERROR_GATTS_SYS_ATTR_MISSING)
        {
					if (err_code == BLE_ERROR_GATTS_SYS_ATTR_MISSING)		//Special handling of BLE_ERROR_GATTS_SYS_ATTR_MISSING
					{
							 SEGGER_RTT_printf(0,"\n\r***  BLE_ERROR_GATTS_SYS_ATTR_MISSING ***\n\r");
					}
					else if(err_code == NRF_ERROR_INVALID_STATE)
					{
							SEGGER_RTT_printf(0,"NRF_ERROR_INVALID_STATE \n\r");
					}
					else if (err_code == NRF_ERROR_INVALID_STATE)
					{
							SEGGER_RTT_printf(0,"BLE_ERROR_NO_TX_PACKETS\n\r");
					}
					break;
        }
				else if (err_code != NRF_SUCCESS) 
        {
						SEGGER_RTT_printf (0, "\r\n Error # 0x%x in 'mag_data_burst_xfer'\r\n",err_code);
            APP_ERROR_HANDLER(err_code);											//Unhandled
        }
	}
	if(cnt == TTL_CHUNKS_TEMP)
	{
		burst_xfer_process=0;			//Burst transfer stopped
		cnt = 0 ;									//Reset for next record transfer
		return NRF_SUCCESS;
	}
}

RE: Loss of notifications when sending them from peripheral to central as bulk transfer

Edvin — Wed, 03 Apr 2019 13:29:51 GMT

Hello,

My guess is that your Burst_characteristic_update() returns BLE_ERROR_NO_TX_PACKETS() meaning your buffer is full. When it returns this, it also means that the softdevice didn't queue the packet that returned this.

I see that you just filter out this return value. I bet that if you add the extra check like you do with BLE_ERROR_GATTS_SYS_ATTR_MISSING and NRF_ERROR_INVALID_STATE, you will see that it is printed.

since you increase your counter, cnt++ regardless if Burst_characteristic_update() returns NRF_SUCCESS or BLE_ERROR_NO_TX_PACKETS, these packets are never sent.

I suggest that you increase the count only if err_code == NRF_SUCCESS.

Something like this:

uint32_t temp_data_burst_xfer(uint32_t* read_buffer_temp)
{
	 static uint8_t cnt = 0;			//Counting the chunks transfered 
   uint32_t        err_code;
	
	while (cnt < TTL_CHUNKS_TEMP && burst_xfer_process)
  {
			  //cnt++;		// Next 20 byte block to send
        err_code =  Burst_characteristic_update(&m_our_service, read_buffer_temp, cnt);		//Sending 20 bytes [cnt represents which block]
				if (err_code == BLE_ERROR_NO_TX_PACKETS ||
            err_code == NRF_ERROR_INVALID_STATE || 
            err_code == BLE_ERROR_GATTS_SYS_ATTR_MISSING)
        {
                    if(err_code == NRF_SUCCESS)
                    {
                        cnt++;  // <-- add this
                    }
					else if (err_code == BLE_ERROR_GATTS_SYS_ATTR_MISSING)		//Special handling of BLE_ERROR_GATTS_SYS_ATTR_MISSING
					{
							 SEGGER_RTT_printf(0,"\n\r***  BLE_ERROR_GATTS_SYS_ATTR_MISSING ***\n\r");
					}
					else if(err_code == NRF_ERROR_INVALID_STATE)
					{
							SEGGER_RTT_printf(0,"Burst transfer halted due to error NRF_ERROR_INVALID_STATE \n\r");
					}
					else if(err_code == BLE_ERROR_NO_TX_PACKETS)
					{
					        SEGGER_RTT_printf(0,"BLE_ERROR_NO_TX_PACKETS. Don't increase cnt++");
					}
				break;
        }
				else if (err_code != NRF_SUCCESS) 
        {
						SEGGER_RTT_printf (0, "\r\n Error # 0x%x in 'mag_data_burst_xfer'\r\n",err_code);
            APP_ERROR_HANDLER(err_code);											//Unhandled
        }
	}
	if(cnt == TTL_CHUNKS_TEMP)
	{
		burst_xfer_process=0;			//Burst transfer stopped
		cnt = 0 ;									//Reset for next record transfer
		return NRF_SUCCESS;
	}
}

I also noted that you increment your counter before you start sending. I believe this means that you skip your first measurement.

If you receive BLE_ERROR_NO_TX_PACKETS, and you want to save some battery, you can, instead of just keep trying to send until it receives NRF_SUCCESS, wait until you receive the BLE_GATTS_EVT_HVN_TX_COMPLETE event, and then continue sending notifications after this. This is described in the sd_ble_gatts_hvx() softdevice call.

Best regards,

Edvin