Cant program Tiny261 from factory

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#1
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Hi all

I have received 200 loaded PCBs from my contract manufacturer, each with a ATtiny261V-10SU onboard. I am unable to connect via ISP. AVR Studio cant talk to the AVR. If I replace the AVR with one I have from stock, then it works just fine. I've check all the track wiring etc and it's all good (and therefore proved by inserting another AVR which works fine).

The design uses the onboard oscillator, so from factory I should be able to communicate ok. I had thought that maybe for some strange reason they had somehow been changed to external oscillator, so I injected both a 1MHz and a 100KHz clock signal and still nothing.

The codes on the bottom of the chip vary only slightly from the ones I have in stock, but are close enough that I don't suspect the chips are fakes, although that is still a possibility. I've emailed Atmel to try and get confirmation of serial numbers etc, but no response in 2 days. My supplier assures me the chips came from Digikey, so they shouldn't be fake anyway.

Is there anything else I should be trying that I can't think of? Replacing 200 AVR's is getting boring.

Cheers - Matt

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how about the lock bits ????
did your manufacturer set these by any chanse ?
if they did change the fuses they might have also messed up the lock bits.
I asume you changed the programming speed to below the 1/4 of the clock ( which might be 1/8 of the xtal when you have a clk/8 fuse bit )

regards

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I haven't been able to do anything, including read the signature byte which you can still do with the lock bits set. My supplier tells me that they didn't do any programming at all, and since I never send my firmware to China, I can't see why they would have done any programming at all.

I have set the ISP frequency to every setting, but I normaly just use 57.6KHz which should work from default settings.

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Are you sure the installed chips are oriented correctly on the board? Not turned 180 degrees? Just a thought.

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Good thought CirMicro, but alas, no the chips are installed in the correct orientation. Other thoughts I'm having is possibly they have been overbaked during the soldering process. But we buy through a fairly large PCB company. I don't think they would be overbaking.

Matt

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another stupid idea might be that you have used the wrong pins for programming.
check and double check the datasheet and perhaps on one board mount a programming connector.

also check that the ISp lines are not loaded. to much load on them will also give programming problems.
Perahps take of 1 chip and then program it outside the PCb and check if the chips are the problem or perhaps the PCb

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Use a multimeter in diode mode to check the protection diodes on all the pins. Between gnd and pin, between vcc and pin. Use resistance mode too on the reset pin. Make a map of the bad part and the good part by writing down all those measurements. Do the 'fingerprints' match?
Just because the stuffer bought from digikey does not guarantee that the parts that got put on the board were the ones ordered. Because obviously, something is not as advertised.

/Kasper

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I doubt I have the ISP pins wrong (which of course I've checked anyway, even with a CRO to see the programmer do its thing). My replacement parts wouldn't ISP if I had the pins wrong.

Also the ISP pins are dedicated pins not used for anything else so loading shouldn't be the problem.

I've already swapped over the 50 I need for my current client, so I'll have to put the fault finding aside for a few days while I get the product out the door then come back to revisit the problem.

Thanks for the ideas so far guys.