Before connecting a UART sensor or controller to Sige7, identify which UART you intend to use and how your image configures its pins. A header pin label alone does not establish that Linux has enabled the matching serial controller.
1. Separate the debug console from your application UART
ArmSoM documents UART2 as the Sige7 console UART. On images using Rockchip’s fiq_debugger, the debugger and the ordinary driver for the same UART must not be enabled together.
For a peripheral project, choose an appropriate documented application UART and keep a working recovery console while developing. See the ArmSoM UART guide.
2. Match the board, image and overlay
Record your image filename and running kernel:
uname -r
Check which configuration files actually exist:
ls -l /boot/armbianEnv.txt /boot/uEnv/uEnv.txt
A missing-path message is useful information: different images use different boot configuration layouts. The presence of a file is only a clue; verify which file the installed image actually reads.
ArmSoM’s configuration and device-tree guide discusses armbianEnv.txt, while its UART instructions also show a uEnv.txt workflow. Follow the documentation matching your image instead of copying an overlay line between unrelated releases.
3. Verify the exact pin function
Confirm all of the following before editing configuration:
- Physical header pin numbers and their orientation.
- UART controller and pin-mux group exposed on those pins.
- Required overlay supplied for your board and kernel.
- Whether another enabled function already uses the pins.
- Peripheral and board UART logic levels.
Do not substitute an overlay for another Rockchip SoC merely because its filename contains the same UART number.
4. Apply one documented change and verify
Back up the active configuration before editing. Apply the image-specific UART change, reboot normally, and inspect the resulting device nodes and kernel messages:
ls /dev/ttyS* /dev/ttyFIQ*
sudo dmesg
Missing matches can be reported as-is. A device node’s existence alone does not prove that the intended header pins are correctly configured.
With power off, connect GND and cross TX/RX using compatible signal levels. Test with matching baud rate and framing, following the peripheral’s specification.
If it fails, share the board revision, image filename, selected overlay, physical pins, serial device path, settings and relevant messages. Keep any debug-console startup log with the report.