Hello,
I’ve made a small Android app that can control USB relay boards (1–8-channel, CH340/FT232) directly via USB OTG. It supports switching individual channels, toggling, and works with common low-cost relay modules.
The app can also be paired with a remote controller (link is shared directly from the app together with a pairing code), so it’s possible to control the relay over the internet without setting up servers.
I’m posting it here in case someone is working with USB relay modules and needs an out-of-the-box solution without writing USB code.
The app is available on Google Play as Relay Controller.
https://play.google.com/store/apps/details?id=com.separdsoft.relaycontroller
There’s also a short demo video on YouTube.
https://www.youtube.com/@Relaycontroller
If you try it with different relay boards or have suggestions, feel free to comment.
AI: Could you share which specific relay board models or brands you’ve tested the app with so far?
I’ve tested the app with several USB relay boards based on CH340 and FT232 chips, including:
1-channel and 2-channel CH340 relay modules (generic).
4-channel FT232 relay board.
8-channel CH340 relay module.
In addition, the app also includes support for devices with the PJRC (Teensyduino) vendor ID, which I use for testing compatibility with custom USB-serial hardware.
Most of these modules are generic boards commonly sold on AliExpress/eBay, so compatibility should be broad. If anyone tries other models, I’d appreciate the feedback.
AI: Are there any particular Android versions or device requirements for the app to work properly with USB OTG?
The app requires Android 7.0 (API 24) or higher and a device that supports USB OTG host mode.
Most modern phones/tablets meet this, but there are a few requirements:
The device must support USB OTG (some budget models don’t).
Depending on your phone, you may need a USB-C to USB-A OTG adapter.
No root or special permissions — it uses the standard Android USB Host API.
I’ve tested it successfully on Android 10 through 15 on Samsung, Motorola, and Pixel devices.
If you try it on other devices, I’d be happy to hear your results.
I’ve made a small Android app that can control USB relay boards (1–8-channel, CH340/FT232) directly via USB OTG. It supports switching individual channels, toggling, and works with common low-cost relay modules.
The app can also be paired with a remote controller (link is shared directly from the app together with a pairing code), so it’s possible to control the relay over the internet without setting up servers.
I’m posting it here in case someone is working with USB relay modules and needs an out-of-the-box solution without writing USB code.
The app is available on Google Play as Relay Controller.
https://play.google.com/store/apps/details?id=com.separdsoft.relaycontroller
There’s also a short demo video on YouTube.
https://www.youtube.com/@Relaycontroller
If you try it with different relay boards or have suggestions, feel free to comment.
AI: Could you share which specific relay board models or brands you’ve tested the app with so far?
I’ve tested the app with several USB relay boards based on CH340 and FT232 chips, including:
1-channel and 2-channel CH340 relay modules (generic).
4-channel FT232 relay board.
8-channel CH340 relay module.
In addition, the app also includes support for devices with the PJRC (Teensyduino) vendor ID, which I use for testing compatibility with custom USB-serial hardware.
Most of these modules are generic boards commonly sold on AliExpress/eBay, so compatibility should be broad. If anyone tries other models, I’d appreciate the feedback.
AI: Are there any particular Android versions or device requirements for the app to work properly with USB OTG?
The app requires Android 7.0 (API 24) or higher and a device that supports USB OTG host mode.
Most modern phones/tablets meet this, but there are a few requirements:
The device must support USB OTG (some budget models don’t).
Depending on your phone, you may need a USB-C to USB-A OTG adapter.
No root or special permissions — it uses the standard Android USB Host API.
I’ve tested it successfully on Android 10 through 15 on Samsung, Motorola, and Pixel devices.
If you try it on other devices, I’d be happy to hear your results.
