Support for BH1750FVI sensor on Armbian / Orange Pi Zero 3 (non-RPi SBC)

[twometre]

Summary

Successfully running lunarsensor on an Orange Pi Zero 3 (Allwinner H618) with a BH1750FVI sensor on Armbian Bookworm Minimal. Sharing setup notes in case it helps other non-Raspberry Pi users.

Hardware

Component	Detail
SBC	Orange Pi Zero 3 (1GB, Allwinner H618)
Sensor	BH1750FVI (I2C, ADDR→GND = 0x23)
OS	Armbian Bookworm Minimal (kernel 6.12.58-current-sunxi64)
I2C Bus	/dev/i2c-2 (mapped from i2c3-ph overlay)

Wiring

BH1750FVI → Orange Pi Zero 3 (26-pin header)
VCC  → Pin 1  (3.3V)  ← Pin 1 is on the debug header side, NOT the USB side
SDA  → Pin 3  (PH5 / I2C3)
SCL  → Pin 5  (PH4 / I2C3)
GND  → Pin 6
ADDR → Pin 9  (GND) → address 0x23

Key differences from Raspberry Pi setup

1. I2C overlay must be loaded via configfs

armbianEnv.txt with overlays=i2c3-ph does not reliably load on boot. Workaround — create a systemd service:

[Unit]
Description=Load I2C3-PH overlay via configfs
After=local-fs.target sys-kernel-config.mount
Before=sysinit.target

[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=/bin/bash -c 'mkdir -p /sys/kernel/config/device-tree/overlays/i2c3-ph && cp /boot/dtb/allwinner/overlay/sun50i-h616-i2c3-ph.dtbo /sys/kernel/config/device-tree/overlays/i2c3-ph/dtbo'

[Install]
WantedBy=multi-user.target

2. Port must be 80

lunarsensor hardcodes port 80 for sensor discovery regardless of LunarSensorPort defaults key. The log confirms:

Starting sensor check for lunarsensor.local:80/ambient_light

Solution: run FastAPI on 8772 and proxy via nginx on port 80.

3. lunarsensor.local hostname resolution

On networks with MDM-managed DNS or split-tunnel VPN, .local mDNS does not resolve. Workaround — add to /etc/hosts on the Mac:

10.10.50.43 lunarsensor.local

4. User must be in i2c group

sudo usermod -aG i2c $USER

Otherwise the FastAPI process returns -1.0 lx silently.

Feature request

Would it be possible to make the sensor discovery port configurable, or document that port 80 is required? The LunarSensorPort defaults key appears to have no effect currently.

Result

Sensor Mode working with real-time lux updates on Lunar. Tested with two external monitors (LG UltraGear + Philips 345E2).

[alin23]

Thanks for the info! The port is configurable, everything is in the README: https://github.com/alin23/lunarsensor#pointing-lunar-to-the-sensor-server

The LunarSensorPort defaults key appears to have no effect currently

That is false, the code using that setting is in SensorMode.swift which is a Pro feature so it is encrypted. AI can't see that.

[twometre]

Thanks for the clarification! I missed the README section — the correct key is sensorPort, not LunarSensorPort. That explains why it had no effect. I'll update my notes and remove the nginx workaround. Appreciate you taking the time to respond!

[alin23]

wish you could write the messages yourself instead of letting an AI do it. I prefer talking to humans.