implementing a USB UART device with AVR USB

Guest · Post by **Guest** » Fri Jun 13, 2008 1:29 am

Would it be possible to implement a USB serial port device with AVR USB? That is, when plugged in, I want the AVR USB device to appear to the host as a COM port.

High speed communication is not important - I just want users to be able to open up Hyperterm and interact with the device.

I know I could do it by using a USB UART chip like a FT232, but I'm just wondering if it could all be done in software.

sonicss · Post by **sonicss** » Fri Jun 13, 2008 5:18 am

Of course it is possilbe.

for more information pls visit:

http://www.obdev.at/products/avrusb/prjinterface.html

Guest · Post by **Guest** » Fri Jun 13, 2008 6:12 pm

Thanks! I missed that project.

Post by **christian** » Sun Jun 15, 2008 8:15 pm

I want to add a note: Projects based on AVR-CDC don't work on all operating systems and they may fail on some hosts. If you want a device which you can sell to others, please find a different solution. If you want something which works for you, then just build it.

bassai · Post by **bassai** » Sun Jun 29, 2008 12:04 am

I tried to implement a AVR-USB device with USART interface to another AVR.
But I get USB timeouts and my USART doesn'T work.

dmesg: usbfs: USBDEVFS_CONTROL failed cmd usbtest rqt 64 rq 1 len 4 ret -110

Any ideas? I have DEBUG_LEVEL=0...

Post by **christian** » Mon Jul 07, 2008 5:24 pm

If you use interrupts for the UART, you must declare them so that the USB interrupt can interrupt the UART interrupt.