37 lines
2.2 KiB
Markdown
37 lines
2.2 KiB
Markdown
# Gadget Mode to setup a serial connection over USB
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Prepare Raspberry Pi OS connection over a microUSB serial cable
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Important: choose either PiUART or OTG. If you do both, it is possible that neither will work. Also, you will want to disable the serial console if you are trying to use that serial port for communicating with other devices. Important reading: Raspberry PI UART configuration
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USB-OTG method (Works on Zero, Zero W, and Compute Module)
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Based upon Adafruit guide: https://learn.adafruit.com/turning-your-raspberry-pi-zero-into-a-usb-gadget/serial-gadget:
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Look for the SD card reader on the VM under "Devices > USB" and click on it Iff you get errors, you may have to shut down the VM and set the USB version to 2.0 or 3.0
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The Boot and Root partition should mount in Linux under /media/$USER/boot and /media/$USER/rootfs
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Navigate to /media/$USER/boot and edit:
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config.txt: add "dtoverlay=dwc2" at the end
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cmdline.txt: remove "init=/usr/lib/raspi-config/init_resize.sh" and add "modules-load=dwc2,g_serial" to the end. Make sure everything is on one line!
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Eject the card
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Boot the pi with a keyboard and monitor attached
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Login
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sudo systemctl enable serial-getty@ttyGS0.service
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sudo systemctl start serial-getty@ttyGS0.service
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# connecting to the serial terminal
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If using a Linux VM, you will need to pass the Pi USB connection there. This is similar to the procedure for accessing an Arduino.
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Start the Linux VM if you haven't already
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Menu: Devices > USB
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Look for "Silicon Labs CP210x USB to UART Bridge" and click on it.
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Run "ls -l /dev/ttyU*" to check if port /dev/ttyUSB0 is found. The Pi will most often be accessible over this port.
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The user must be in the dialout group to access it. Use the Linux command: id -to check if you are in the group. If not in the dialout group, use:
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sudo usermod -a -G dialout <username>
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You will use the screen app in Linux to access the Pi. You can install it with:
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sudo apt install screen
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You should now gain access to the Pi with:
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sudo screen /dev/ttyUSB0 115200
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Press enter and you will be prompted to log in to the Pi with default credentials. User: pi - PW: raspberry
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