DFU-Programmer tips & tricks

I recently got an AtmelAT90USBKey to play around with. I'm going to use it to prototype a USB controller for the MRF49XA transceiver I made a while ago. Thatpost is still in progress, but I had trouble getting started with DFU-Programmer on the mac, so I thought I'd make a post about those problems so it may help others having the same trouble. I know that I found next-to-nothing when I was googling for it.

I didn't have too much trouble installing DFU-Programmer, the version included in macports works just as well as the version I compiled from source. The first problem I encountered was a weird memory error when I tried to dump the device memory. When I'm just starting with something, I usually don't jump in, guns-blazing, and start erasing and flashing stuff. I start by dumping memories, usually it's not going to break something that already works. In this case, I ran up against a brick wall.

$ dfu-programmer at90usb162 dump -debug 5 > temp
target: at90usb162
chip_id: 0x2ffa
vendor_id: 0x03eb
command: dump
quiet: false
debug: 5
device_type: AVR
---- command specific below ----
Request for 12288 bytes of memory failed.

There is literally no reason I can think of for this error to occur, it's not using very much memory, and I've never seen a malloc fail when there is a reasonable amount requested. I've searched for about 2 days for the answer, and I've still come up with nothing. The only hits I've seen are simply source listings for DFU-Programmer, where the printf for the error is! Getting around it (temporarily, even!) is a multi-step process, and requires a device erase(which makes it just about useless):

1. Erase: dfu-programmer at901287 erase -debug 5
2. Reboot into the boot loader (again)
3. Erase (again, because a write-protect error: see below)
4. Flash device: dfu-programmer at90usb1287 flash file.a90 -debug 5
5. Dump flash memory: dfu-programmer at90usb1287 dump -debug 5 > out.dump

Eventually, it worked. I'm not at all happy with the performance of dfu-programmer on the mac. I'm considering forking it and making a proper mac application, but I'm not sure I'm willing to support it at the moment.Ultimately, though, it does work, it's just not as functional as I had hoped.

The write-protect error I mentioned above looks like this:

target: at90usb162
chip_id: 0x2ffa
vendor_id: 0x03eb
command: flash
quiet: false
debug: 5
device_type: AVR
---- command specific below ----
validate: true
hex file: USBKEY-series6-ms_df-2_0_2.a90
Device is write protected.
Error while flashing.

This error is strange (I've never set the write protect flag!), but easy to fix. It is common for micro controllers to clear the write-only flags when the part is erased. That's the solution here, just erase it:

dfu-programmer at90usb162 erase

Now, you should be able to program the device. Even when I hadn't set the protection flags (knowingly, anyway) I got the write protect error.

The moral of the story is that dfu-programmer doesn't work very well on the mac, and the magic fix seems to be erasing and rebooting the part often. Good luck! If you have noticed something stupid I'm doing, I'm all ears. It seems like others haven't had these problems, so I'd love to hear if there's something I'm doing wrong.

Note that the AT90USBKey was provided by Element 14 in exchange for writing this post.