Permission Denied Dialout Group Fix | Generated by AI
Here’s the full picture:
✅ Problem Found: Permission denied — not in dialout group
The fix is applied, but here’s what was happening and what you need to know:
Root Cause
/dev/ttyUSB0exists and your Arduino (via CH340 USB-serial chip, ID1a86:7523) is detected- The port is owned by
root:dialoutwith permissionsrw-rw----(660) - Your user wasn’t in the
dialoutgroup → no read/write access
What I did
- Added you to the
dialoutgroup viausermod -aG dialout xiaoxin - Verified with
newgrp dialoutthat the port is now accessible
You still need to
Log out and log back in (or reboot) for the group change to stick permanently in your terminal emulator, or do:
exec su - $USER
in the current terminal to get a new login shell with the dialout group active.
Quick test once the group is active
screen /dev/ttyUSB0 9600
Or with your Arduino IDE / app — it should now connect fine.
Summary
| Item | Status |
|---|---|
| Device detected | ✅ CH340 on /dev/ttyUSB0 |
Driver loaded (ch341-uart) |
✅ |
| Permissions | ✅ Fixed (was missing dialout group) |
| Port in use by another process | ❌ No — clear to connect |
| App can connect | ⏳ After re-login / exec su - $USER |