ATmegas with split personalities

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#1
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While working on my debugWIRE hardware debugger, I came a across a very funny phenomenon. Some AtmegaX8 chips identify themselves correctly when the device signature is queried using the SPI protocol. After switching to debugWIRE, the MCUs queried using the corresponding debugWIRE command gave a different device signature. And this is not only one chip, but seems to be consistent over the different flash sizes:

ATmega48A -> ATmega48PA

ATmega88A -> ATmega88PA

ATmega168A -> ATmega168PA

ATmega328 -> ATmega328P

 

This is not a real problem, but I noticed that MPLAB X got confused. I wonder whether you have seen something like that as well. BTW: The chips without an A-suffix that I own do not show this behavior (except for the 328, of course).

 

Wish you a happy new year,

Bernhard

 

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I don't think I have seen this, but then again, I don't recall ever checking the device signature using DW either. 

Hopefully you have resolved your issue or ignored it and moved on and have not been waiting for a reply for so long! sad

Could it be a MPLAB X issue?   What version were you using?

 

Jim

 

 

FF = PI > S.E.T

 

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ki0bk wrote:

Could it be a MPLAB X issue?   What version were you using?

 

That ^^^^. It'd be interesting to see the actual hex values returned.

#1 Hardware Problem? https://www.avrfreaks.net/forum/...

#2 Hardware Problem? Read AVR042.

#3 All grounds are not created equal

#4 Have you proved your chip is running at xxMHz?

#5 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand."

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You can use the appropriate avrdude "-c programmer" e.g. xplainedmini_dw, dragon_dw,  atmelice_dw, powerdebugger_dw, jtag3dw, ...

 

I would guess that it reads the Signature correctly.  However I don't have the chips that you mention in #1 (except ATmega328P)