ISP strangely flakey on ATtiny44, 84

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I've made up some very simple boards that take a Tiny44 or 84. The first few, using 44s, programmed and worked just fine. The next 3, built with both 44s and 84s, fail to identify correctly, giving non-zero IDs that are pretty consistent but sometimes vary in one or two bits. I'm using AS 6.1 and a Dragon (latest firmware).

I've checked continuity for power, ground and the 4 ISP pins, and all is good. Parts are from Mouser, not some unknown source. Target Vcc reads back 5.2V. Anybody seen failures like this? I haven't. Kind of at a loss at this point.

BTW, if I connect one of the working boards back up, they still ID and work correctly.

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Didja slow down before trying to deflower the virgins?

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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theusch wrote:
Didja slow down before trying to deflower the virgins?

Good point. Yes, I slowed to 125 kHz, then tried all the way down to 2.something kHz.

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Run your tests with known software. e.g. avrdude -c dragonisp

If you get bad behaviour, report back.
If avrdude works ok, make a bugZilla report to Atmel about AS6.1 / atprogram.exe

I only possess one ATtiny84. I can try it with AS6.1 / Dragon if you suspect that it is an AS6.1 problem.

David.

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david.prentice wrote:
Run your tests with known software. e.g. avrdude -c dragonisp

If you get bad behaviour, report back.
If avrdude works ok, make a bugZilla report to Atmel about AS6.1 / atprogram.exe

I only possess one ATtiny84. I can try it with AS6.1 / Dragon if you suspect that it is an AS6.1 problem.

David.


Never used avrdude before, but that sounds like a good approach. Thanks.

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OK, tried it with Studio 4.12. Had to back down the Dragon firmware to work with 4.12. After doing so, all works well on all the unconnecting boards. So it's either AS 6.1 or the new Dragon firmware. I'll look at reporting it.