Receiving data from UART via a peripheral device

[Thomas]

Hi

I am working with a Nordic nrf52840dk using segge and sdk 16.

I am using the nordic UART example in examples/peripheral/uart.

The issue I am having is that my data being sent to this device can not be read from the nordic board.

Below is an example of the code going into my Putty terminal from my UART peripheral device.

1,1183,1,1169
1,1183,1,1169
1,1183,1,1169
1,1183,1,1169
1,1183,1,1169
1,1183,1,1169

This device has 4 wire connections RX,TX,CTS and RTS. My connections are listed below:

Note this is the default.

#define RX_PIN_NUMBER  8
#define TX_PIN_NUMBER  6
#define CTS_PIN_NUMBER 7
#define RTS_PIN_NUMBER 5

The first thing i tried was running the code with no change to see if app_uart_get(&cr) would pull this data. Unfortunately it did not. It does however, pull data that i type into the terminal.

What I want to do is to take this data from the UART(Sensor data) and store it as a variable for handling later on.

I which to know how I can pull this data from the serial connection.

Side note when the device (UART) is plugged in printing from putty does not run. If I unplug the device then printing works fine.  Below is my main code (from example).

int main(void)
{
    uint32_t err_code;

    bsp_board_init(BSP_INIT_LEDS);

    const app_uart_comm_params_t comm_params =
      {
          RX_PIN_NUMBER,
          TX_PIN_NUMBER,
          RTS_PIN_NUMBER,
          CTS_PIN_NUMBER,
          UART_HWFC,
          false,
#if defined (UARTE_PRESENT)
          NRF_UARTE_BAUDRATE_115200
#else
          NRF_UARTE_BAUDRATE_115200
#endif
/*
#if defined (UART_PRESENT)
          NRF_UART_BAUDRATE_115200
#else
          NRF_UARTE_BAUDRATE_115200
#endif
*/
      };

    APP_UART_FIFO_INIT(&comm_params,
                         UART_RX_BUF_SIZE,
                         UART_TX_BUF_SIZE,
                         uart_error_handle,
                         APP_IRQ_PRIORITY_HIGH,
                         //APP_IRQ_PRIORITY_LOWEST,
                         err_code);

    APP_ERROR_CHECK(err_code);

#ifndef ENABLE_LOOPBACK_TEST
    printf("\r\nUART example started.\r\n");

    while (true)
    {
        uint8_t cr;
        while (app_uart_get(&cr) != NRF_SUCCESS);
        while (app_uart_put(cr) != NRF_SUCCESS);

        if (cr == 'q' || cr == 'Q')
        {
            printf(" \r\nExit!\r\n");

            while (true)
            {
                // Do nothing.
            }
        }
    }
#else

    // This part of the example is just for testing the loopback .
    while (true)
    {
        uart_loopback_test();
    }
#endif
}

[Einar Thorsrud]

Hi,

It is not entirely clear to me, but the serial terminal on the PC is via the onboard debugger, right (USB connector on the left of the board)? If you are using that (or have the debugger enabled in general so that IF OFF is not asserted, then you should use different pins for the external UART device. In other words, connect the UART pins between the nRF and another device to some available GPIO pins, and update the pin number defines.

[Thomas]

Thanks for your response, I am using the onboard usb connector (the one in the top-middle of the board). This is where my putty serial terminal connects to. Jlink CDC UART PORT(COM5)

I have tried redefining the pinouts to:

#define RX_PIN_NUMBER  NRF_GPIO_PIN_MAP(0,3)//8
#define TX_PIN_NUMBER  NRF_GPIO_PIN_MAP(0,28)//6
#define CTS_PIN_NUMBER NRF_GPIO_PIN_MAP(0,4)//7
#define RTS_PIN_NUMBER NRF_GPIO_PIN_MAP(0,29)//5

I have then connected my device to those pinout.

However, I now no longer see that information (from the uart device) to putty, nor can I use a printf command and see the result.

When I  run this through the dubugger after running the APP_UART_FIFO_INIT and checking the error code it goes to NRF_BREAKPOINT_COND;

I then get this in the call stack area of the debugger.

What other details do you need to help resolve this issue?

[Thomas]

Ok Einar in the TX and RX code example i used your setup and did get the sent and received data correctly. Then I used my sensor and it can receive the data. Well it at least prints to the RTT viewer. So I think that means I can use this data.

One issue though which, is a separate issue is that I need to use the RX code in the ble folder as I'll need to read the uart data then output it to a bluetooth advert.

I've got the code to output a ble advert. I just need to merge it with the uart get code you provided. 

My question is will this code (RX) work if I copy and paste it into my ble_beacon example?

[Thomas]

So the data I am getting printed is Received string: "1,1169,1,1167". Which is a string variable. How can i parse this into two locations of data. E.g data 1 = 1169 and data 2 = 1167?

Then I need to advertise this via my ble packet which has 2 bytes for each data.

[Einar Thorsrud]

Hi Thomas,

Yes, but you will need to adjust the sdk_config.h of the project to add it to to get the correct UART configuration, and add any missing source files .

[Thomas]

How do I add app_uart.h and app_error.h? to the project?

I include them and it can't find them

[Einar Thorsrud]

I don't have any knowledge about location data and how you would want to encode this data in the advertising packet. But once that is done, you just add it to the advertising packet in the format you need.

The advertising packet data can be updated whenever you get new data, but there are a few possible problems you might face. Generally, the thing you need to remember is that you are not allowed to update a buffer that is currently advertised, so you should either use an alternating set of advertising data buffers or stop and start advertising when you update it.

[Thomas]

Don't worry about the advert stuff, thats working. 

I just need to add the app_uart and app_error to the project. So i can merge the projects.