Connecting UART Data to development board PCA10040

[sherif]

I am trying to transfer data from a USB to serial converter board (called board A) to the nrf5 board (called board B). I made the connection over a bread board, the transmitter from board A  is connected to pin 06 on board B, it is also at the same time connected to the receive in Board A. I am sending zeros and receiving zeros at board A. I want to see these zeros at board B.

The baud rate on both is adjusted to 19200. The ground is connected on both boards.

I started uart_pca10040 example but I don't get any data received on board B. I tried to connect pin 5 with 7 for CTS and DTR but also I don't see any data.

The data voltage on Board B is 2.1 V.

[awneil]

sherif said:

connected to pin 06 on board B

Have you checked carefully that there is nothing on the board already "occupying" that pin?

In particular, remember that the PCA10040 has an on-board USB-to-Serial converter connected to the nRF52 chip...

Check the User Guide & Schematics ...

[sherif]

I know it has an on-board-usb-to serial converted but the target here is to transfer data from another device to this board. As far as I understand, when I checked the board pin assignment it says in page 8, p0.06 is TXD and pin 0.08 RXD. Please correct me if I misunderstood it.

infocenter.nordicsemi.com/.../nRF52_DK_User_Guide_v1.2.pdf

[sherif]

the schematics is not clear .. is there any internal chip configuration on the mcu level?

[awneil]

sherif said:

the schematics is not clear

In what way(s), exactly, is it "not clear" ?

sherif said:

is there any internal chip configuration

The firmware in the chip configures it.

[sherif]

what is could reach right now, when I press a button I come to this line

    NRF_BREAKPOINT_COND;
    // On assert, the system can only recover with a reset.

[awneil]

sherif said:

the schematics is not clear

In what way(s), exactly, is it unclear?

sherif said:

is there any internal chip configuration

The firmware running in the chip does the configuration.

[sherif]

how can I run the external serial port ? these stuff are not clear even there is no example. should I use HWFC?

[awneil]

I think you need to go back to the unmodified UART example in the SDK.

Spend time with the debugger, a terminal, and an oscilloscope exploring that, and understanding how it works.

Use the oscilloscope to observe the data between the nRF52 to the on-board USB-to-UART.

Once you have this thoroughly understood, then - and only then - move on to modify that example to talk to a separate USB-to-UART converter.

Once you have that working, then you can move on to getting 2 boards to talk to each other.

[sherif]

I made this. But when i change the pins, nothing is getting into action. I can not disable the on board usb to uart and input external serial data. It seems that the pins need to be changed in many places. I need help or a step by step to solve it. I am now 3 days on it.

[sherif]

i have been working with this issue now 1 week, and investigated many things, but i can not input data externally. I need  a step by step guide. Guys, if you made it previously, please assist me how to do it.  I changed the pin assignments for RX and TX but it does not make any change

[sherif]

Lets rephrase my question. I have the following simple code in the main, based on ble_app_uart. it initializes the uart and writes data to it. First i see UART started on the terminal. Second i want to see these bits. When i connect a led to pin 23 which i used for Tx, i don't see any thing.

    uint32_t                     err_code;
    app_uart_comm_params_t const comm_params =
    {
        .rx_pin_no    = RX_PIN_NUMBER,
        .tx_pin_no    = SER_CON_TX_PIN, //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
    };

int main(void)
{
    uart_init();
    printf("\r\nUART started.\r\n");
    for (;;)
    {
        idle_state_handle();
               uint32_t err_code = app_uart_put(255);
                if ((err_code != NRF_SUCCESS) && (err_code != NRF_ERROR_BUSY))
                {
                    NRF_LOG_ERROR("Failed receiving NUS message. Error 0x%x. ", err_code);
                    APP_ERROR_CHECK(err_code);
                }
                else
                {
                     NRF_LOG_ERROR("received data");
                }
            
    }
}

[sherif]

Solved:

Here is the solution:

1- Use pin 3 and 2 and disable the rts and cts

static void uart_init(void)
{
    uint32_t                     err_code;
    app_uart_comm_params_t const comm_params =
    {
        .rx_pin_no    = 3, //RX_PIN_NUMBER,
        .tx_pin_no    = 2,//TX_PIN_NUMBER,
//        .rts_pin_no   = 17, //RTS_PIN_NUMBER,
//        .cts_pin_no   = 18, //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);
}

2- don't connect any leds because it seems that drawing any amount of rel. current will disable the data transfer

3- connect board A (serial to usb) to board B (PCA10040)

Gnd-Gnx

Rx (board A) - Pin 2 (Board B)

Tx (board A) - Pin3 (Board B)

4- Install the mac usbto serial port driver  (or use Serial app because it has internal drivers but cost 25$)

My driver was based on this link

https://blog.sengotta.net/signed-mac-os-driver-for-winchiphead-ch340-serial-bridge/

5- Using cool Term connect to your usb-serial port

6- using segger

in my main loop i sent 1 and 255 for testing

    for (;;)
    {
        idle_state_handle();
               uint32_t err_code = app_uart_put(1);
                if ((err_code != NRF_SUCCESS) && (err_code != NRF_ERROR_BUSY))
                {
                    NRF_LOG_ERROR("Failed receiving NUS message. Error 0x%x. ", err_code);
                    APP_ERROR_CHECK(err_code);
                }
                else
                {
                     NRF_LOG_ERROR("received data");
                }
            
    }

7- if you connection is correct, you should see the 1 (byte sent) in cool term