How to print UART message in "ble_app_uart" project in SDK15.2

[chianglin]

Hi,

Does "ble_app_uart" project can print debug message from "UART" interface? How can I do this job?

PS. My UART Port is at P0.18 (TX) and P0.19(RX).

Thank you,

Chianglin

[Vidar Berg]

Hi,

The ble_app_uart project prints debug messages over Segger RTT by default.  But you can use printf() if you wish to write data to the UART.

Vidar

[chianglin]

Hi Vidar,

I had try to use printf() to write data to UART, and the UART interface is connect to PC, but I can not find any data  in PC console.

My environment is:

1. Use Nordic's nRF52832 EVM board.

2. Use "ble_app_uart" project of SDK15.2, and I doesn't modify any thing.  Actually, there have "printf()" function in main.c.

But I still can not found any message from PC via UART interface.

How can I fix this problem?

Thank you,

Chianglin

[Vidar Berg]

Hi Chianglin,

Is this the Nordic devkit (nRF52 DK - PCA10040)? In that case, you shouldn't need to modify anything, UART data will be written to the JLINK CDC UART port (virtual com port) on your PC. You just need a serial client and select the correct COM port and baudrate (default 115200)

Best regards,

Vidar

[chianglin]

Hi Vidar,

I am using the EVM board like following image.

Yes, it can print debug message via "JLink CDC UART Port" to PC.

If I want to print debug message to other UART pin (for example: P0.06 for TXD and P0.08 for RXD), how to modify the source code to do this job?

Thank you,

Chianglin

[Vidar Berg]

Hi Chianglin,

You can change the pin numbers in uart_init(), but the UART pins will not be routed to the JLink chip then. 

Best regards,

Vidar

[chianglin]

Hi Vidar,

Can I modify TXD to P0.18 and RXD to P0.19 for UART output?

Can I modify following code to do this purpose?

static void uart_init(void)
{
    uint32_t                     err_code;
    app_uart_comm_params_t const comm_params =
    {
        .rx_pin_no    = 19	/*RX_PIN_NUMBER*/,
        .tx_pin_no    = 18	/*TX_PIN_NUMBER*/,
        .rts_pin_no   = RTS_PIN_NUMBER,
        .cts_pin_no   = CTS_PIN_NUMBER,
        .flow_control = APP_UART_FLOW_CONTROL_DISABLED,
        .use_parity   = false,
#if defined (UART_PRESENT)
        .baud_rate    = NRF_UART_BAUDRATE_115200
#else
        .baud_rate    = NRF_UARTE_BAUDRATE_115200
#endif
    };

    APP_UART_FIFO_INIT(&comm_params,
                       UART_RX_BUF_SIZE,
                       UART_TX_BUF_SIZE,
                       uart_event_handle,
                       APP_IRQ_PRIORITY_LOWEST,
                       err_code);
    APP_ERROR_CHECK(err_code);
}

In original source code, the TXD, RXD is define at P0.06, P0.08.  The UART can print message and I can find BLE device on "RF UART APP".

But when I modify to P0.18 and P0.19, the "nRF UART APP” can not find this BLE device.

Do I also need to do something?

Thank you,

Chianglin

[Vidar Berg]

chianglin said:

Can I modify TXD to P0.18 and RXD to P0.19 for UART output?

It shouldn't be a problem, but make sure that the RXD pin isn't left floating as that may cause framing errors, etc due to noise.

[chianglin]

Hi Vidar,

I think P0.18 and P0.19 don't have problem to define as UART, because this 2 pins can work correct when I use "peripheral\uart" project.

The "nRF UART APP" can not find the BLE device which describe In my previous mail. May be the device had been crash, so BLE can not work.

The only change between “BLE can work or not" is "I modify the tx_pin_no and rx_pin_no in structure "comm_params".

Would you please tell me why my device is crash after I do these change?

Thank you,

Chianglin