Something really bizarre!

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I was using ADC Ch1 of ATmega8535L, running at 5V and internal 1MHz oscillator. I accidently connected that pin to -22V terminal of my power supply, but the best thing is, my chip is intact!

What happens now is, the Ch1 always reads some 0.8V (I hope some internal protection diode is doing something), and rest of the chip's peripherals are intact. Any thoughts?

Cheers,
Vignesh

If everything seems to be coming onto your way, then you are probably driving on a wrong lane..

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Quote:

Any thoughts?

Don't use that pin anymore. Or throw away the chip.

Lee

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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It sounds like you just blew out that one channel. I doubt very much if it is recoverable. Have you tried that pin with other functions? I don't know if this sort of thing would just take out the ADC circuitry of the pin, or disable the pin entirely.

Regards,
Steve A.

The Board helps those that help themselves.

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Quote:
Any thoughts?

Hmmm, I wonder what's for dinner?

Four legs good, two legs bad, three legs stable.

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Nothing bizarre about it.!

You exceded the safe operating input voltage of the ADC pin and it gave up it's smoke.

I wouldn't think their could be any thoughts about it except decide to live with it or replace the microcontroller.

Now, if you can figure out how to put the smoke back in and get the destroyed ADC pin working again, there might be some money to be made for that rechnology.

You can avoid reality, for a while.  But you can't avoid the consequences of reality! - C.W. Livingston

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Quote:

Now, if you can figure out how to put the smoke back in and get the destroyed ADC pin working again, there might be some money to be made for that rechnology

I think it was wreck-nology that caused the problem in the first place !

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Unless you're desparate, it's probably best to throw the chip away.

Trouble is, you have absolutely no idea what else on the chip might have been affected
Some time in the future, you could waste days chasing an obscure bug, only to eventually find that it's some side-effect of this little incident.

Hence I suggest that you bin it - unless that's absolutely out of the question (even then, you should plan to replace it as soon as possible).

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Been there, done that. I have blown an entire port (PORTC) on a 40-pin AVR by plugging in an ISP to it while the chip was doing PWM out, and then repeatedly trying to reprogram the FLASH. The chips still worked, but PORTC was totally blown.

The lessons here are:

(1) Don't plug the wrong thing in, or you will blow part of a chip.

(2) Because you will plug something in wrong, If you suddenly see a PORT, PIN, or something else stop working, try another chip.

(3) Because you will plug see things suddenly stop working, keep extra chips around.

(4) Beacuse you want to keep extra chips around, those 64 pin TQFP chips that sell for $40 soldered to carrier boards are a PITA (pain in the rear-end.) For example, the STK 300 is no longer what I consider a great prototyping platform. I meesed up the fuses on an AtMega128 over a year ago, and finally have an Atmel AVR JTAG to fix them with. (That's why I bought an STK 502 + STK 500.) Still, $15 chips suck. I try to do as much as I can with $2.65 AtMega168 chips.

(5) Don't believe that a chip that comes up as existing under ISP, Microwire, or JTAG really is OK.

(6) We need a way to test every feature on the chip, but I don't know how to do it. Maybe we would need a board that loops PORTs to PINs so we can test the chips? If PORTA and PORTB are wired togeather, we could output from A and input on B to test them, the reverse the direction? I might need to work on that and a test program.

Andy Out!

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Hello there! Thanks for your replies! I got many different views! I would try using that pin as a Digital IO and let me see if that still works!

I am confortable with that chip, as long as there are some 4 ADC channels, and SPI. Until I blow them out, I would use the same chip for protos! Good point by awneil about the side effects.

I wonder why the line 'Andy Out!' comes in every post of Recycled electonics! But a very nice reply, thanks!

Cheers,
Vignesh

If everything seems to be coming onto your way, then you are probably driving on a wrong lane..

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vignesh wrote:
I wonder why the line 'Andy Out!' comes in every post of Recycled electonics! But a very nice reply, thanks!

You have your signature, I have mine.

Andy Out!

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Hmmm, but does it specifically mean or point someone else?! I am just curious!

Cheers,
Vignesh

If everything seems to be coming onto your way, then you are probably driving on a wrong lane..

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You probably burned the internal protection diode, it will now be a continuous short-circuit to GND and/or VCC

I like cats, too. Let's exchange recipes.

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Andy is 'signing off' his 'radio transmission' with 'Over and Out!' like radio operators have done for decades. It is a 'handshake protocol' for a 'half duplex communication medium' so two people don't key the mic at the same time and get a collision.

Imagecraft compiler user

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Bob,

Except that when I did my RF exams for my PPL my radio instructor was horrified by the use of "over and out" on TV/film dramas. Sure they are a "protocol" but "over" means "I have finished talking it is now your turn" while "out" means "I have finished talking and as far as I'm concerned this is the end of our conversation". So you can't use both over and out in the same transmission. In ASCII terms I guess "over" could be something like "ACK" while "out" is "EOT"

Cliff

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But....

Wouldn't saying "out" be like haning up on someone while "over and out" is more like saying "I'm now done talking and I'm going to hang up now so you don't have to respond to my last transmission"

Or should the expression be more like "Roger and Out"....heh. Oh...I guess it's like Andy's sig...."Andy Out" but you wouldn't use your real name. It would have to be a cool code name like "Viper Out" I guess thats not to cool...

Wouldn't "Roger" be the
"Over: be a
and "OUT: be the

I'm not a radio operator so I was just wondering...hehe..Oh and it's late and I had 1, 2 many wobbly pops after rec hockey..

Over and out....err
Roger and Out...maybe

Ocnek OUT :D

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As a totally unrelated (to the OP) sidenote, the name "Rodger Wilco", fearless janitor anti-hero from the much-loved Space Quest adventure series of the last decade stems from the radio terminology slang for "Rodger that, will comply" (message understood). It's sad that I know these things.

- Dean :twisted:

Make Atmel Studio better with my free extensions. Open source and feedback welcome!

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Quote:
It's sad that I know these things.

You are a treasure trove of trivia :)