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 Using The Enhanced/Dual power Willem Programmer
 Issues erasing and writing to AT29C020		  Forum Locked
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PRL519

USA
4 Posts
Posted - 06/09/2023 :  13:02:58  Show Profile
I just started using the GQ4x4 programmer. Works great except for a bunch of Atmel 29C020 flash chips I bought on eBay. They were listed as new, but of course they're not.

Some questions:

1) A few of the chips have an "unknown" ID. Can that be modified? If so, can the GQ4x4 modify it? Should I still be able to work with the chip if it has an unknown ID? Or does the ID determine how the GQ4x4 programs it?

2) I'm unable to erase or write to any of my AT29C020 chips. I assume that's because they're locked (I have a dozen of them; it's unlikely they're all bad). I went to the Lock/Unlock option and clicked the Unprotect button in the All Sectors group (the Protect button was greyed out). The log showed:

Unprotect ....
* Unprotect Ended *

Whatever that means. If the Unprotect operation succeeded, shouldn't the Protect button then be enabled and the Unprotect button greyed out?

No matter what I tried with Lock/Unlock, I'm still unable to erase or write to any of the chips.

3) How does the speed setting affect writing and erasing? The erase operation is very fast regardless of the speed setting (and the erase still fails).

4) The AT29C020's data sheet shows the write sequence for locking and unlocking the chip. Is there any way to know what the programmer is doing when I click the Unprotect button?

Any hints or tips would be appreciated.

Thanks.
Reply #1

ZLM

2945 Posts
Posted - 09/19/2024 :  15:24:20  Show Profile
AT29C020 can not be unloked on any programmer.
The chip is designed for one time lock only. No way to unlock it.
So, if your chip is locked, then you need a new blank chip.
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