ATMega128 ICs seem dead :-(

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I recently bought some ATmega128A chips on eBay from China (a previously trusted supplier called H_quality). I can't get any life out of them at all. I thought maybe they were fake chips but I've tested that all the ground pins are joined together inside the IC and the same for the positive supply pins. No connection between these pins and any other pin (just checking they weren't all shorted inside). If they were fake chips I would expect all the pins to be shorted or disconnected. Hmmm.

 

Having scoured both AVR Freaks and the internet in general I've come across various posts where people have mixed up the MISO and MOSI pins as this chip for some reason uses different pins, PDO and PDI, for serial programming. I've triple checked these connections are correct, supplied 5V to all the positive pins including AVcc, 0 volts to all the ground pins. Programmer reset signal goes to to reset pin 20 and SCK to pin 11. Even though I think these ICs are supposed to use the internal oscillator I've put a crystal and capacitors just in case it needs them. Nothing. I mean, AVRDude says "target does not respond".

 

I can't see any reason why the fuse bytes could be wrong because I haven't touched them as I can't even get the ICs to respond.

 

Having worked on this for several days on and off I have now put these ICs and the carrier PCBs into a box marked "faulty". I've got plenty of other AVR chips which work fine (not ATM128's tho), but it's just annoying - I would report these as faulty to the supplier if I could be confident that I hadn't missed anything. 

 

Has anybody got any suggestions as to any other mistakes I could have made?

 

Cheers,
Zadok.
 

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some time ago I had the problem that atmega324p controllers didn't respond to avrdude. It turned out that the cpus were intact, but they had pre-programmed fuses.

 

Take a look here: https://www.avrfreaks.net/forum/...

 

Last Edited: Wed. Oct 21, 2020 - 09:23 PM
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You need an external clock signal to XTAL1 pin.

 

I would expect you to solder the TQFP-64 directly to the target pcb first.

Then program via JTAG or ISP.

 

I don't see any point in having a carrier pcb.

 

The first job is to remove the M103C fuse.    Until you do this you have a brain-dead Mega103.

The second is to enable the Internal RC.

 

David.

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You didn't mention supply decoupling caps. I would put 100nF across each Vcc and ground, as well as a 10uF bulk cap.

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AVRDude says "target does not respond".

Make sure you are trying to program them at the slowest possible ISP speed....<1/4th of whatever clock the chip is using (unknown, so use slowest possible) & it won't program. 

a previously trusted supplier called H_quality

yeah, sure thing !!  Send them $5000 and ask them to send it back--that will be plenty of proof. 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

Last Edited: Wed. Oct 21, 2020 - 09:55 PM
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some time ago I had the problem that atmega324p controllers didn't respond to avrdude. It turned out that the cpus were intact, but they had pre-programmed fuses.

That's interesting, so I can't really discount the possibility that the fuses are messed up :-/

Last Edited: Wed. Oct 21, 2020 - 10:41 PM
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I got scammed with fake chips on ebay before. Not worth the hassle. Lots of fakes from China. Buy from Digikey or another authentic distributor....
Also, some avr chips the program pins Do Not correspond to the MosI Miso SCK pins on the pinout diagram. They have different pins to use for programming MosI Miso SCK specified deep in the datasheet memory programming section.

Last Edited: Thu. Oct 22, 2020 - 05:07 AM
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welshzadok wrote:
can't really discount the possibility that the fuses are messed up 

Not necessarily "messed up" - just programmed for some application which requires a crystal.

 

That's a pretty common requirement - eg, I think, Arduino!

 

There's a tutorial on recovering from the "wrong" fuse settings:

 

https://www.avrfreaks.net/forum/tutsoft-recovering-locked-out-avr

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