Set up hardware to display output

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Currently, each real-time core supports a TX-only UART. RTApps can use this UART to send log output from the device. During application development and debugging, you typically need a way to read and display the output. The HelloWorld_RTApp_MT3620_BareMetal sample shows how an application can write to the UART.

Use a USB-to-serial adapter such as the FTDI Friend, to connect the UART on the real-time core to a USB port on your machine. You will also need a terminal emulator to establish a serial connection with 115200-8-N-1 terminal settings (115200 bps, 8 bits, no parity bits, one stop bit) to display the output.

To set up the hardware to display output from an RTApp, follow these steps. You'll need to refer to the documentation from your hardware manufacturer to determine the pin locations. If you're using hardware that follows the MT3620 reference board design (RDB) hardware, like the MT3620 Dev Kit from Seeed Studios, then looking at the RDB interface headers may help you to determine the pin locations.

  1. Connect GND on the USB-to-serial adapter to GND on your dev kit. On MT3620 RDB hardware, GND is Header 3, pin 2.

  2. Connect RX on the USB-to-serial adapter to IOM4-0 TX on your dev kit. On MT3620 RDB hardware, IOM4-0 TX is Header 3, pin 6.

  3. Connect the USB-to-serial adapter to a free USB port on your development machine and determine which port the serial device is connected to.

    • On Windows, start Device Manager, select View > Devices by container, and look for "USB UART". For example, FT232R USB UART indicates the FTDI Friend adapter.

    • On Linux, type the following command:

      dmesg | grep ttyUSB

      The port should be named ttyUSBn, where n indicates the port number. If the dmesg command lists several USB ports, the one that is connected to the typically the last one reported as attached. For example, in the following, you would use ttyUSB4:

    ~$ dmesg | grep ttyUSB
[  144.564350] usb 1-1.1.2: FTDI USB Serial Device converter now attached to ttyUSB0
[  144.564768] usb 1-1.1.2: FTDI USB Serial Device converter now attached to ttyUSB1
[  144.565118] usb 1-1.1.2: FTDI USB Serial Device converter now attached to ttyUSB2
[  144.565593] usb 1-1.1.2: FTDI USB Serial Device converter now attached to ttyUSB3
[  144.570429] usb 1-1.1.3: FTDI USB Serial Device converter now attached to ttyUSB4
[  254.171871] ftdi_sio ttyUSB1: FTDI USB Serial Device converter now disconnected from ttyUSB1

  4. Start a terminal emulator program and open a 115200-8-N-1 terminal to the COM port used by the adapter. See the documentation for the terminal emulator to find out how to specify the port and speed.