CH340 is a chip that convert USB data to serial data. Of cause the method discuss here can be applied to other USB-serial converter chips, such as PL2303 etc. It is helpful when you want to do serial communication with your circuit board. Usually I write Python scripts to interact with serial devices.
Find the Device
In your terminal, run
If your device is plugged, you can see an item about it. If not, make sure your circuit board is functioning well.
dmesg | grep ttyUSB
Usually the name should be something like
Change Your Permission
chmod to change device access permission.
sudo chmod 777 /dev/ttyUSBx
(replace the ‘x’ with your device number.)
Try to Open the Serial Port in Python
In python script, use
pyserial library to handle the serial devices.
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import pyserial ser = serial.Serial('/dev/ttyUSB0', '9600', timeout=2) ser.write('your command\r\n'.encode('ascii')) # convert to ASCII before sending it buf = ser.read(100) # read 100 bytes print(buf.decode('utf-8'))
Basically this is how it works.
Note: On Windows, the
/dev/ttyUSB0 string should usually be
COM0 etc. That’s the difference.
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