nrf52832 Uart SDK14

[T_chapelle]

Context : I am using a nrf52832 to communicate via UART to a STM32 on a custom board. I've based my work on the Ble nus service example. Main change from the DK is that i don't have an external 32khz so i enabled NRF_CLOCK_LF_SRC_RC

I recently updated the nrf52832 code from SDK12/s132 version 3.0 to SDK14 /s132 version 5.0 because i had issues with some Android devices.

Problem : The BLE part is doing fine now with all the devices that were causing trouble (advertisement, connection, characteristic reading/writing) but the UART part is now unstable.

Hardware flow control is enabled UART_DEFAULT_CONFIG_HWFC, baudrate is set to 115200. On the SDK14, i've tried UART_EASY_DMA_SUPPORT but it's not working, so i switched to using UART_LEGACY_SUPPORT.

At first, uart communication is good at transmitting / receiving but after a while, the connexion hang and i have to reset the whole board. The uart_event_handle doesn't seems to have a APP_UART_COMMUNICATION_ERROR or APP_UART_FIFO_ERROR event but what happen is a high state on the CTS pin of the nrf52. Also, UART_RX_BUF_SIZE value seems to change the delay/latency after which i have this problem.

After debugging i did get those two info from the uart :

EVENTS_CTS 1 EVENTS_NCTS 1 EVENTS_ERROR 0 ERRORSRC 0

Can someone give me hints on what to look after ?

(already saw devzone.nordicsemi.com/.../ and checked the pinout)

EDIT: the high state is on the RTS pin of the nrf52 not the CTS (blue line is RTS, yellow is RX)

[T_chapelle]

Yes, i do call app_uart_get in the uart_event_handle fonction that i initialized in :

const app_uart_comm_params_t comm_params =
{
    RX_PIN_NUMBER,
    TX_PIN_NUMBER,
    RTS_PIN_NUMBER,
    CTS_PIN_NUMBER,
APP_UART_FLOW_CONTROL_ENABLED, 
    false,
UART_BAUDRATE_BAUDRATE_Baud115200
};

APP_UART_FIFO_INIT( &comm_params,
                   UART_RX_BUF_SIZE,
                   UART_TX_BUF_SIZE,
                   uart_event_handle,
		APP_IRQ_PRIORITY_LOW,
                   err_code);

and in the uart_event_handle :

void uart_event_handle(app_uart_evt_t * p_event)
{
	uint8_t serial_char;
	uint16_t i;

    switch (p_event->evt_type)
    {
    case APP_UART_DATA_READY:

			if(app_uart_get(&serial_char) == NRF_SUCCESS)
			{
...