[SOLVED] Atmel OTP AT27c010 programming error

[Zed80]

Hi

I got a few samples from Atmel (DIP format), unfortunatly my two attempts to program them were incomplet. It worked up to a third or a quarter of the memory space then i got the error message (from memory) saying the buffer was not the same that the chip read.

The part that is written is ok and conform but now since they are OTP chips, they are lost I am afraid. I still have a few left and would be happy to find the way to program them error free.

I have a Willem 5.0e board and I used the 27c010/27c1000/27c1001 default setting. With switches and the jumpers set up like on the picture. And I know the board works fine since I am able to write some more classic UV erasable 27c4000 Eproms for instance.

The specs deal with a fast programming mode with a 100us loop:
http://www.atmel.com/Images/doc0321.pdf

Unfortunatly I am not sure what parameter to change.

What could I do to improve the success rate ?

Thanks in advance if you know any information, or have any comment.

[Ezo]

What error message you have ?
Usually some bits from byte not written (bit status from 1 to 0 ). Try overwrite chip with the same file. Check programming voltage , Vcc 5.6 and Vpp 12.7 in Test H/W mode without target chip.

[Zed80]

I don't remember exactly, it is the standard error when a word is written but the error check reading on it just after is bad.

[Zed80]

Hi, I'am back on this subject as I am in a great need of theses chips now.

The specs says that the write pulse should be 100uS (+/- 5%).

Obviously that was the trouble. The default settings for the windows programmer are:
tWP=140uS
tWC=20uS

So for sure tWP has to be set to 100uS.

Question is what value should i set for tWC ? The specs don't speak about write cycle, and I can't figure what it does.

Any clue or advice ? As they are OTP chips I cannot afford wasting the few left. Thx !

[Ezo]

Pulse lenghts are OK. Keep default values of Willem SW.
Check voltages Vcc and Vpp before programming , without chip !
Clean PLCC32 chip pins sideward softly to avoid bad chip contact in socket .
Start with first failed attempt chips, overwrite the same (!) file.

[Zed80]

Unfortunatly you cannot overwrite "One Time Programmable" chips, as their name tells it. I tried but in vain.

I think voltages are good since i burned "normal" 27c4001 and 27c1000 without any trouble. Sure, checking the voltage myself won't kill me but I don't expect any trouble since it works well with the other UV erasable chips.

I know that dirt can be a problem, but there are shiny new, right out of the tube.

The specs say 12v for VPP and it is what it should get from the board.

It is most probably a pbm of timing, me think, since OTP eproms are not the same kind of the usual UV eproms. Defaults setting need to be adapted relativly to the specs, don't you think ?

[Zed80]

Hi, just a quick word to say that I successfully burnt a bunch of those Atmel OTP chips.

Here are the settings I used:

tWP=100.0uS
tWC=60.0uS

They all passed !

(The only one that didn't pass was with tWC=20.uS wich is the default, then I upped tWC and it was just fine)

[Ezo]

They all passed !

Great

Unfortunatly you cannot overwrite "One Time Programmable" chips, as their name tells it. I tried but in vain.

agree, usually non applicable, OTP.
Programming - means convert selected bits from 1 to 0 in each byte. In case of failure, usually bits remain 1. Apply the same initial file (!) and overwrite.