entering programming mode.. FAILED! axon

[wanglalm]

Please help.  I click the program button before I turn on the axon, and now I can't program the mcu anymore. Is there anyway to reset it.

[Admin]

Can you describe the problem in detail, going through all the steps? I'm not sure what problem you are having.

[wanglalm]

I'm using a avrisp mkll programer, avr studio 4
The problem started when I try to upload a new program using isp, and forgot to turn on axon.
when I turn on axon and try to upload again, avr studio is giving me this entering programming mode failed message.

I'm getting the same message if I click on read signature, or fuses.

[bens]

It is definitely possible to corrupt an AVR by trying to program it while it is unpowered, but I expect the avrispmkii programmer to be smart enough not to try programming an unpowered AVR.

- Ben

[Admin]

Check your battery voltage just in case . . .

Unfortunately this is a bug with the ATmega's, that on very *rare* occasions, if you program it without power, it'll cause a crystal fuse corruption.

Here is how you fix a bricked Axon:
http://www.societyofrobots.com/axon/axon_FAQ.shtml#brick

Also, see the diagram on page 48 of the ATmega640 datasheet.

You will need something that creates a high frequency square wave, like a function generator or another microcontroller using PWM, applied to XTAL1. Then using your ISP programmer you can change the fuse back to the crystal:
http://www.societyofrobots.com/axon/axon_FAQ.shtml#fuses

Think about it for a bit, and if you get stuck, feel free to ask.

It is definitely possible to corrupt an AVR by trying to program it while it is unpowered, but I expect the avrispmkii programmer to be smart enough not to try programming an unpowered AVR.

I find it's smart enough about 2/3rds of the time. Probably has to do with partially charged capacitors on the mcu board even though it's off.