Raspberry Pi 3 + Official 7-inch Touchscreen Photo Frame with Ambient Light Sensor Auto-Brightness (BH1750FVI + I2C + Python)

After building a cloud-connected photo frame with Raspberry Pi 4, I had a spare Raspberry Pi 3 and official 7-inch touchscreen sitting around. I turned them into another photo frame — and added a GY-30 BH1750FVI ambient light sensor to automatically adjust display brightness based on the room’s lighting.

Hardware

Raspberry Pi 3

Raspberry Pi 3 Model B Single-board Computer

Amazonで見る

Official 7-inch Touchscreen

800×480px, 24-bit RGB color, 60 fps, up to 10-point multitouch.

Raspberry Pi Official 7-inch Touchscreen LCD

Amazonで見る

Case for the Official Touchscreen

Designed to house both the Raspberry Pi 3 Model B and the 7-inch display.

Raspberry Pi & 7-inch LCD Touchscreen Case ABS (RS Components, Black)

Amazonで見る

Connecting the Display

Follow the Raspberry Pi Touch Display official documentation to assemble the display.

Display Rotation Setting

By default the display is rotated 180°. The fix depends on your OS version.

For Bullseye and earlier (legacy/FKMS mode):

sudo vi /boot/config.txt

Add the following line:

lcd_rotate=2

Slideshow Program

The slideshow uses the Python script from the cloud-connected photo frame project (photoView4).

Display Brightness Control

Running the display at full brightness all the time is uncomfortable in a dark room. The official 7-inch display allows brightness control by writing a value (0–255) to a sysfs file:

echo "100" | sudo tee /sys/class/backlight/rpi_backlight/brightness

Adding an Ambient Light Sensor (BH1750FVI)

Rather than setting brightness manually, I wanted it to adjust automatically based on ambient light.

Parts

WINGONEER GY-30 BH1750FVI Digital Light Intensity Sensor Module I2C for Raspberry Pi

Amazonで見る

ELEGOO 120pcs Dupont Jumper Wires Male-Female / Male-Male / Female-Female Set

Amazonで見る

Connecting to Raspberry Pi via I2C

The BH1750FVI communicates over I2C. Refer to the Raspberry Pi GPIO pin layout for wiring.

Wiring Table

Verifying the Sensor (Python)

After wiring, confirm data is coming through. Based on a reference implementation on GitHub:

#!/usr/bin/python3

import smbus

Bus = smbus.SMBus(1)
Addr = 0x23
LxRead = Bus.read_i2c_block_data(Addr, 0x11)
print("Illuminance: " + str(LxRead[1] * 10) + " lx")
LxRead2 = Bus.read_i2c_block_data(Addr, 0x10)
print("Brightness: " + str((LxRead2[0] * 256 + LxRead2[1]) / 1.2))

Running it confirms the sensor is working:

root@raspi3-photo:~# python br.py
Illuminance: 1650 lx
Brightness: 990.8333333333334

Auto-brightness Control Program

The final program adjusts backlight brightness smoothly based on ambient light readings:

• Target brightness levels are defined per illuminance range
• The display brightness is incremented or decremented one step at a time toward the target
• The I2C sensor is polled every 300ms — polling faster than this results in incorrect readings with SMBus

Sensor Placement

The sensor is mounted on the protruding back section of the case, where it receives ambient light from the room.

Source Code

The complete program (object-oriented version) is on GitHub:

GitHub - yukishita/lcdBrightness2: Auto-brightness control for Raspberry Pi official display using BH1750FVI light sensor

Demonstration

The brightness adjusts smoothly as ambient light changes:

Summary

Adding the light sensor makes the photo frame genuinely pleasant to use — bright during the day, dimmed at night, automatically.