Not dead, just mostly dead

So, to work on my breadboard Sanguino, I needed some Atmega644P's. They were on back order everywhere, and the Sanguino zip files seemed to suggest that it also worked with Atmega644's. Something like $7+ quantity 1, $5 quantity 25. So I got 25 from mouser.

After building the breadboard I needed to download the bootloader. Connected my AvrISPmkII. And ... first chip wouldn't take it - got some weird error from avrdude (more later). Second chip worked like a charm. Ditto third. I figured I'd fried the first chip. Later, I tried to burn the bootloader on the remaining chips. All got the same error:


sudo avrdude -p m644 -c avrisp2 -P usb

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.01s

avrdude: Device signature = 0x000000
avrdude: Expected signature for ATMEGA644 is 1E 96 09
Double check chip, or use -F to override this check.

avrdude done. Thank you.


Now, no way did I fry all them chips. Nor could they all be bad, maybe it was a glitch on the bread board? But that didn't make sense, what about them two good 644's that were working just fine ... So I ignored it for the time being.

So, I finished my PCB design, sent it in to golden phoenix PCB - yet another suggestion from Zack (thanks Zack!) - and got it back a week later. Arrived on my doorstep a matter of hours after I left to visit my family for a week. Argh! So I got back late Sunday, and built the first board Monday figuring that no way could the first board I ever designed work, that $120 was surely down the tubes, but that I'd debug it and the second set of PCBS would work fantastic. WRONG. First board worked right first time out.

So I decided to burn the bootloader on the rest of my chips. Again, no go, device signature was 000000. On the 23 remaining chips. Every single one dead.

Hmm, but that doesn't make sense. While a bread board might be electrically wonky, I was now pretty sure my PCB was pretty solid. And I couldn't believe I got 23 dead chips from Mouser. So something weird is afoot.

I poke around on google. Pretty much nothing. Except a hint. Some AT Tinys come from the factory with a slow clock setting, and require some other programmer to set a jumper to slow down the download clock.

Maybe my chips weren't quite dead. Maybe they were just mostly dead.

Now the AvrMkIspII has no such jumper. And avrdude didn't seem to have any such thing. Till I read the help again:


-B bitclock Specify JTAG/STK500v2 bit clock period (us).
...
-i delay ISP Clock Delay [in microseconds]



Well that looked promising. Didn't know which to try first, so -B it was. BING! It worked. Now on one chip I needed to slow it down to 4us. The next 6us. And once the 644 bootloader is downloaded, it seems to adjust the clock speed, so there's no need for that nonsense any further.

I'm pretty sure the rest of my chips are fine. Just need to play around with the clock speed for each one.

So, while my chips sure seemed dead, as Miracle Max said, mostly dead is not all dead.