Control robot via serial port

Connect USB-to-UART adapter to computer

1. Connect USB-to-UART adapter to USB port. Such adapter (or “CP2102 USB UART serial converter”) can be found on eBay for $2-$3

USB2UARTAdapterCP2102

2. Find on which device the adapter has connected – run following command in the Terminal

ll /sys/class/tty/ttyUSB*

UbuntuFindSerialPortsUSB2UARTCP2102Connected

3. Shorten by a wire pins “RX” and “TX” of the adapter – signal from the pin “TX” (“transfer data”) will travel to the pin “RX” (“receive data”) of the same adapter

USB2UARTAdapterCP2102ShortenedTXRX

4. Start the program “CuteCom” (click on the icon “Dash Home”¬†UbuntuDashHome , type “cutecom” in the field “Search” and click on the found icon “CuteCom”)
5. In the window of the started “CuteCom” – type found device name in the field “Device” (e.g. “/dev/ttyUSB0”)
6. “Baud rate” can have any value from the list
7. Clear the checkbox “Handshake: Hardware” (“Handshake: Software” can be ticked or cleared)
8. Click the button “Open device”

hint Device exists but cannot be opened

Most likely the reason is read and write access permissions. Command chmod can change it. Following command adds (+) permissions read, write and execute to all of following groups: the owner, the group and other users

sudo chmod a+xwr /dev/ttyUSB0

This command need to be run every time the USB-to-UART adapter is reconnected. To avoid this routine – add the user to a “dialout” group (in this example “user1”) and relogin the user or restart the computer

sudo adduser user1 dialout


9. Type any text in the field “Input” and hit “Enter” – this text will be sent to the adapter, sent from its pin TX to its pin RX via the shortage wire, transferred back to the computer and printed in the field “Output”
10. Disconnect a shortage wire – sending text will not be received anymore

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