General discussions about V-USB, our firmware-only implementation of a low speed USB device on Atmel's AVR microcontrollers
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Post by Michael » Wed Nov 28, 2007 2:42 pm


I'm, currently doing some investigations for a small project of mine... It would be a sort of USB-RS485 interface. And this AVR-USB seems like a perfect fit...

However I have some questions...

1. Are there any drivers that makes it really simple to communicate with it? or do I need to write my own drivers?

2. If such drivers exist, do they work with Windows Vista?

Objective Development
Objective Development
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Post by christian » Sat Dec 01, 2007 1:52 pm

I don't know how you want to control the communication direction of your RS485 interface. If the device should look like a serial interface, I'd recommend that you implement a CDC class device. See for an example. This class of device does not need a Windows driver, only a .inf file which tells it to use the drivers which ship with Windows.

If you need more control (e.g. over the communication direction), you need to write your own windows driver. I would recommend a HID class device in this case. Using HID for data communication is demonstrated in Automator and (more sophisticated) in AVR-Doper. Both projects are available at

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