Getting logging output with nRF5340 DK

When connected to a computer, the nRF5340 DK emulates virtual serial ports. The number of serial ports depends on the DK version you are using.

Serial ports are referred to as COM ports on Windows, /dev/ttyACM devices on Linux, and /dev/tty devices on macOS. To list Nordic Semiconductor devices connected to your computer together with their serial ports, open a terminal and run the nrfutil device list command. Alternatively, check your operating system’s device manager or its equivalent.

nRF5340 DK v2.0.0 serial ports

When connected to a computer, the nRF5340 DK v2.0.0 emulates two virtual serial ports. In the default configuration, they are set up as follows:

  • The first serial port outputs the log from the network core (if available).

  • The second serial port outputs the log from the application core.

nRF5340 DK v1.0.0 serial ports

When connected to a computer, the nRF5340 DK v1.0.0 emulates three virtual COM ports. In the default configuration, they are set up as follows:

  • The first serial port outputs the log from the network core (if available).

  • The second (middle) serial port is routed to the P24 connector of the nRF5340 DK.

  • The third (last) serial port outputs the log from the application core.

To use the middle COM port in the nRF5340 DK v1.0.0, complete the following steps:

  1. Map RX, TX, CTS and RTS pins to four different pins on the development kit, using, for example, devicetree overlays. See the following example, using the nordic,nrf-uarte bindings.

    &pinctrl {
   uart0_default_alt: uart0_default_alt {
      group1 {
         psels = <NRF_PSEL(UART_TX, 0, 20)>,
                 <NRF_PSEL(UART_RX, 0, 21)>,
                 <NRF_PSEL(UART_RTS, 0, 18)>,
                 <NRF_PSEL(UART_CTS, 0, 16)>;
      };
   };

   uart0_sleep_alt: uart0_sleep_alt {
      group1 {
         psels = <NRF_PSEL(UART_TX, 0, 20)>,
                 <NRF_PSEL(UART_RX, 0, 21)>,
                 <NRF_PSEL(UART_RTS, 0, 18)>,
                 <NRF_PSEL(UART_CTS, 0, 16)>;
         low-power-enable;
      };
   };
};

&uart0 {
   status = "okay";
   compatible = "nordic,nrf-uarte";
   current-speed = <115200>;
   pinctrl-0 = <&uart0_default_alt>;
   pinctrl-1 = <&uart0_sleep_alt>;
   pinctrl-names = "default", "sleep";
};

  2. Wire the previously mapped pins to TxD, RxD, CTS, and RTS on the P24 connector.

Log output from TF-M on nRF5340 DK

By default, the nRF5340 DK v1.0.0 requires that you connect specific wires on the kit to receive secure logs on the host PC. Specifically, wire the pins P0.25 and P0.26 of the P2 connector to RxD and TxD of the P24 connector respectively.

On the nRF5340 DK v2.0.0, only two virtual COM ports are available. By default, one of the ports is used by the non-secure UART0 peripheral from the application and the other by the UART1 peripheral from the network core.

There are several options to get UART output from the secure TF-M:

  • Disable the output for the network core and change the pins used by TF-M. The network core usually has a child image. To configure logging in an nRF Connect SDK image, see Logging in nRF Connect SDK.

  • You can wire the secure and non-secure UART peripherals to the same pins. Specifically, physically wire together the pins P0.25 and P0.26 to P0.20 and P0.22, respectively.

  • If the non-secure application, network core, and TF-M outputs are all needed simultaneously, additional UART-to-USB hardware is needed. You can use a second DK if available. Connect the P0.25 pin to the TXD pin, and P0.26 to the RXD pin of the external hardware. These pins provide the secure TF-M output, while the two native COM ports of the DK are used for the non-secure application and network core output.