Continuing on the theme of my last post, here are libusb-win32 drivers for the Atmel AVRISP mkII. Unlike the Atmel-supplied drivers, these support avrdude, and as a bonus they will install on the 64-bit version of Windows 7 without digital signature errors. Yes!
Note that if you want to use the AVRISP mkII with AVR Studio, these are not the drivers you are looking for. You want the ones Atmel provides (if you installed the libusb drivers by mistake, re-run the AVR Studio installer to revert back).
For some time now, those wanting to use the Adafruit Industries USBTinyISP with the 64-bit versions of Windows 7 or Vista were faced with the following errors when attempting to install the device drivers supplied by Adafruit:
For some reason, the 32-bit versions of these operating systems don’t prevent the unsigned drivers from being installed, although they do complain.
There are a few workarounds that involve hacking Windows or disabling digital signature checking, but thanks to a tip by user wayneft on the Adafruit support forums, I was able to make the process much more straightforward.
The USBTiny drivers are based on libusb-win32. Based on some notes I found on the libusb-win32 wiki, I discovered that the latest libusb drivers contain a proper digital signature:
Vista/7 64 bit are supported from version 18.104.22.168 since a Microsoft KMCS accepted digital signature is embedded in the kernel driver libusb0.sys. libusb-win32 based device drivers can also be submitted for Microsoft WHQL testing. Several companies have successfully finished the WHQL testing with their libusb-win32 based driver package. This will allow the customers to install the driver without a warning under current 32bit/64bit Windows.
This is good news!
I downloaded the latest version of libusb-win32 (22.214.171.124) and used the included inf-wizard tool to create new drivers for the USBTinyISP:
I used the Windows device manager to upgrade the broken drivers on my Windows 7 64-bit machine. There is still a warning that “Windows can’t verify the publisher of this driver software” but there are no more errors about digital signatures and the new drivers appear to install and work correctly.
I haven’t done a huge amount of testing with the drivers, but I was able to communicate with the USBTiny via avrdude and flash a simple program to an AVR. I also haven’t tested this fix on Vista, as I don’t have access to a computer running it. If anyone tests these drivers on Vista x64, please post your results in the comments!