sd_ble_gatts_hvx unable to send data for more than 8 times, why?

[Erik]

8.0, multilink example, peripheral, s110 softdevice.

I modified the button_event_handler() function in main.c into this:

static void button_event_handler(bsp_event_t button_action)
{
	uint32_t err_code, i,j;

	if(button_action == BSP_EVENT_KEY_0)
	{
		if (m_conn_handle != BLE_CONN_HANDLE_INVALID)
		{
			static uint8_t value = 0;

			ble_gatts_hvx_params_t hvx_params;
			uint16_t			   len = 1;

			value = (value == 0) ? 1 : 0;

			memset(&hvx_params, 0, sizeof(hvx_params));

			hvx_params.handle = m_char_handles.value_handle;
			hvx_params.type   = BLE_GATT_HVX_NOTIFICATION;
			hvx_params.offset = 0;
			//hvx_params.p_len  = (uint16_t*)(4*sizeof(uint8_t));


			hvx_params.p_len  = &len;
			hvx_params.p_data = &value;

		  RPT:	err_code = sd_ble_gatts_hvx(m_conn_handle, &hvx_params);
			APP_ERROR_CHECK(err_code);
		
			value = (value == 0) ? 1 : 0;

			for (i=0;i<=0xfffff;i++)
			{
			 j++;
			}

			goto RPT;

			if (value == 0)
			{
				err_code = bsp_indication_set(BSP_INDICATE_ALERT_OFF);
				APP_ERROR_CHECK(err_code);
			}
			else
			{
				err_code = bsp_indication_set(BSP_INDICATE_ALERT_3);
				APP_ERROR_CHECK(err_code);
			}
		}
	}
}

so the idea is, whenever I press the appropriate button, the corresponding LED on central board will flash on and off forever since I made the code stuck in a infinite loop.

But that's not what really happened: the LED flashed 4 times, which means 8 bytes of data were transmitted. Then the board (peripheral, s110 softdevice) restted. (Most likely resetted by the APP_ERROR_CHECK(err_code);).

Why is this happenning? It's always 8 bytes, nothing more, nothing less. Truly puzzling.

Can somebody help me? Thanks.

[bjorn-spockeli]

You need to provide us with the error code that causes APP_ERROR_CHECK to reset the chip. This post explains how to find which error code that caused the reset.

Bjørn

[Alex]

Instead of FOR loop you'd better to use nrf_delay_ms(). If you send data too fast you may have error BLE_ERROR_NO_TX_BUFFERS. In that case you just need to retry rather than raise error with reset.

[Erik]

Thanks Alex, does that mean that it is virtually impossible for me to send data at a decent frequency? I.e. faster than finger can press? That's insane. What's the highest data rate if that were true?

[Alex]

Ah, finger press is slow enough so shouldn't trigger that error. Can you put breakpoint in app_error_handler() function and tell us error_code as Bjørn already asked below?

[Erik]

I really wish I could Alex, but see this question below to understand the kind of quandary I'm in: devzone.nordicsemi.com/.../