USB digital I/O (HID interface)

The goal of this project is providing open-source API for low cost USB digital I/O adapters sold on eBay
(search for "USB I/O data acquisition control module for Smart Home").

The device has up to 16 I/O pins configurable as digital input or output, and an user-controlled LED.

These devices currently have only the API for Windows, only in binary DLL form.

We are not associated with the manufacturer(s) of these devices or author(s) of the original software offered by eBay merchants.


HID - based interface does not require any drivers to install, and no simulated COM-ports.
It is easy to detect connected devices and address them.

Details of the device

The device has 16 I/O pins; each pin can be configured as output or input, with optional pullup.
The device has also one green LED which can be set to either off or blinking with constant frequency.

The USB identifiers for these devices conform to the "Free USB-IDs for shared use" document by Objective Development (

The vendor name is "", the model name is "USBIO".
Every board has an unique "serial number" which can be used to select a device, if several of them are connected to the host.
Note: this is not a standard HID 'serial number'! Both USB and HID 'serial number' string (obtained by HID API) on these devices are null.
On all of our devices, the 'serial number' consists of 4 ASCII characters.

API and programming

The source code and binaries are on github. Please watch the github project for updates.

All projects hosted on this wiki Objective Development's projects based on V-USB.

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