ble_central_uart multi-connection cause periodically reset

[Avadacadabara]

Dear all,

I'm trying to modify ble_central_uart (SDK16) to connect two peripherals. I've achieved the connection and been able to print receiving data via UART.

But here is my problem, the connection would break periodically, probabally caused by central system reset. And the period seems depending on UART baudrate, for example 115200 and 230400 would reset every few seconds while 409600 would last several minutes(disconnection period is not that clear in this baudrate). Peripheral data rates is 8800bps each.

One on one connection is quite stable with either peripheral.

Any help will be appreciated.

Thanks!

[Kenneth]

Sounds very much like an assert, and the app_error_fault_handler() is by default setup to reset on error. Please check out the following blog post on how to build with DEBUG so that it can output the line number, file name and error code causing the assert:

https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/an-introduction-to-error-handling-in-nrf5-projects

[Avadacadabara]

Thanks Kenneth!

It turns out to be the "APP_ERROR_CHECK()" right after "app_uart_put". 

I traced the returned value of "app_uart_put" but have found "NRF_SUCCESS" only. I added DEBUG macro to my project, the system would freeze without printing error info instead of frequent reset. 

For now I'm just commenting the "APP_ERROR_CHECK" to maintain system running but somehow I still can't locate the root cause.

Thanks!

[Kenneth]

Have you tried to place a breakpoint in app_error_fault_handler() and wait for the issue to occur? Then you should find the exact error code from app_uart_put(). 

Kenneth

[Avadacadabara]

Hi Kenneth,

I've managed to get the error code, it says  ERROR 4 [NRF_ERROR_NO_MEM] when processing app_uart_put.

Should I adjust the memory address in option target? Or any part of the configuration need to be modified? I'm debugging with SDK16 ble_uart_central template.

Thanks.

[Kenneth]

You can try to increase UART_TX_BUF_SIZE, but you can also find the description for the api useful:

/**@brief Function for putting a byte on the UART.
 *
 * @details This call is non-blocking.
 *
 * @param[in] byte   Byte to be transmitted on the UART.
 *
 * @retval NRF_SUCCESS        If the byte was successfully put on the TX buffer for transmission.
 * @retval NRF_ERROR_NO_MEM   If no more space is available in the TX buffer.
 *                            NRF_ERROR_NO_MEM may occur if flow control is enabled and CTS signal
 *                            is high for a long period and the buffer fills up.
 * @retval NRF_ERROR_INTERNAL If UART driver reported error.
 */
uint32_t app_uart_put(uint8_t byte);

[Avadacadabara]

Hi, I modified the TX_BUF_SIZE and it worked.

Thanks Kenneth