UART APP_UART_COMMUNICATION_ERROR

[PMichael]

Dear Sirs!

I used SDK 12.2. Product was developed some years ago and now I am working for upgrade. One of new features is UART. I faced very strange problem.

I send 14 bytes from PC via FTDI UART 3.3V cable to Nordic and Nordic send back different 14 bytes to PC.

This process repeats each 200 ms

Baud rate 115200 no flow control, no parity

#define UART_RX_PIN_NUMBER 3 //UART Rx
#define UART_TX_PIN_NUMBER 2 //UART Tx
#define UART_CTS_PIN_NUMBER 0xFFFFFFFF //Not connected
#define UART_RTS_PIN_NUMBER 0xFFFFFFFF //Not connected
#define UART_HWFC false

static app_uart_comm_params_t comm_params =
{
UART_RX_PIN_NUMBER,
UART_TX_PIN_NUMBER,
UART_RTS_PIN_NUMBER,
UART_CTS_PIN_NUMBER,
APP_UART_FLOW_CONTROL_DISABLED, //Flow control disabled
false, //No parity
UART_BAUDRATE_BAUDRATE_Baud115200
};

buffers.rx_buf = rx_buf;
buffers.rx_buf_size = 64;
buffers.tx_buf = tx_buf;
buffers.tx_buf_size = 64;

err_code = app_uart_init(&comm_params, &buffers, uart_event_handle, APP_IRQ_PRIORITY_HIGHEST);

despite I use EASY_DMA

#ifndef UART_EASY_DMA_SUPPORT
#define UART_EASY_DMA_SUPPORT 1
#endif

// <q> UART_LEGACY_SUPPORT - Driver supporting Legacy mode

#ifndef UART_LEGACY_SUPPORT
#define UART_LEGACY_SUPPORT 0
#endif

I get sometimes event APP_UART_COMMUNICATION_ERROR error_communication  = 1

It happens randomly. May happen.  immediately or after 2 bytes received or after 6 bytes received

As I understood this value is the same as in register ERRORSRC. Is it correct?

How can I prevent this situation? I put interrupt to highest priority, use easy dma and fifo and despite all this it happens.

What''s wrong? Please help

Best regards

Michael

[Susheel Nuguru]

This is not a hardware issue, as mentioned in the product specification for ERRORSRC register

This is an overrun error which means that the peer is sending data faster than your device can pull from the RXD FIFO. This normally happens when you do not use flow control as there is no way to tell the peer to slow down or pause to avoid RXD FIFO error. 

Either enable flow control or reduce the baudrate on both side to avoid this error. 

If you cannot do both, then you need to optimize your application that the UART RXD post processing is much faster in pulling the RXD data when UART receives any data. This can be done by optimizing your callback handler for uart when new data is received.

[PMichael]

Thank you!

But I use EasyDMA. and FIFO 64 bytes. As I understand EasyDMA shall transfer data to FIFO without processor's interrupt routine? Is it correct? Please look at code that I have sent in my first message. I also opened private ticket for this. Please go to private ticket

[PMichael]

• Case ID: 331565

[Susheel Nuguru]

Not sure why you opened a private ticket with the same query? This thread will look abandoned if we proceed in the private ticket. Let us continue here and please close the other private ticket.

[PMichael]

ok. Can you please answer about easy DMA. If I use easy DMA is it corrent that it transfer data to FIFO automatically without processor? If yes, why still this problem?