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.