MCUmall EPROM BIOS Chip Burner Forum
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 Problem with ATMEL AT27C256

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trip0six Posted - 01/30/2006 : 18:29:10
Well, to whom it may consern. I am trying to write to ATMEL AT27c256 chips for my car. So far I been on this project for a couple of days, up to 15 hours a day, trying this,trying that,using jumpers on 3 and 31, Sometimes I get error 0x0000,or error write sector 0, I am so fustrated. I have about 50 chips and haven't wrote to none. I can get the chip to read,verify,and verify blank. I can not get the chips to erase nor write!!!The chips check out Blank. When I load a .BIN sometimes even when I verify it says something like error 0x0000 buffer??? Don't know whats going on! I researched different sites saying use PCB3 and some say use Willem, Another site says Offset 8000 on somechips and 0 on newer chips. If ene 1 wants to check out one of those sites its PFMFI.ORG ,I JUST NEED SERIUOS HELP! Also I read in my Bios, to set LTP1 to epp,norm. When I do, My cable modem stops working. Please, please, help me for the sake of humanity and keeping me sain!!!
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trip0six Posted - 02/04/2006 : 14:43:49
I have a feeling its the product if you can fix it I could send it to you. I live in Victorville CA. Were are you located? I would love if you could do what evere it would take to fix it. Also if you could, I need 29C256 Eproms. Thanks Email me:
DL Posted - 02/02/2006 : 11:16:08

What is the complete error message? What do you measure for VPP? Designs with the step-up regulator sometimes have problems with not being able to maintain VPP. This usually shows up as program fails at random addresses. Yours is failing at the first byte; check VPP with a 50mA load (~240 ohms). Leave the load for 10-15 seconds and measure again.

With a dual powered programmer with VCC set to at least 5.7V, you shouldn't have any problems programming CMOS EPROMs. I haven't programmed Atmel parts, but have programmed from several other manufacturers.

I have a modification that fixes voltage problems on the dual powered boards. It makes the programmer more reliable for programming EPROMs (NMOS and CMOS), but the USB power option will no longer be available. My mod also gives more voltage options so you can program and blank verify at the proper voltages -- but you still need to know when and what to change them to.

If you're in the US, I can test/repair your board if whoever sold it to can't or won't. It'll cost you for postage, insurance, and my time; but it may save your sanity and your Marriage... For an additional charge, I can fix your voltage problems (voltage drop when programming NMOS EPROMs and lack of voltage options) with an addon board. Regardless of where you bought your programmer, you can check out for help. That board is much more active and many are aware of the limitations of the enhanced and dual powered boards.

I can't do anything for the enhanced universal programmers. Too many problems and no schematic or component diagrams...

trip0six Posted - 02/02/2006 : 01:50:24
I have an Dual Enhanced Willem Programmer. I heard something about putting a 1k resistor inline ("R1" Resistor,) To fix voltage problem?
Is this true? Has ENE 1 wrote to a AT27C256 eprom? My chips verify blank, also I am able to erase them. When I write to them, it says 0x0000 Buffer 0x02 "instantly" I have a UV light that erases my chips.
Thanks for everyones hospitality. We need to help each other in this world, better spiritual balance. I don't preach!!! I get a high off sharing knowledge with others. Even if you feel like you know everything, keep an open mind. Examine your suroundings, and put together what you believe will work to your benifit!!! Thanks again.
ZLM Posted - 01/31/2006 : 14:07:30
I understand your frustration.

For the 27C256 EPROMs, you need to use UV eraser to erase them before doing the write. Also, do a blank check before to write any thing. If the blank check says the chip is not blank, then you need to UV erase again.

Do not try other device type for 27C256, other type just does not work on 27C256.

Like DL said, the programmer does not support ID for EPROMs. So it is gray out from the toolbar.

As long as you can read the chip, the connection and the software installation should be OK.

Let us know which programmer you have, we may give you more info.
DL Posted - 01/31/2006 : 10:41:02

What programmer do you have? 27C256 and 29C256 devices are not interchangeable. The ID function does not work for EPROMs; that's why it's grey'ed out.

If you have an enhanced (USB-only power), it's not good enough for programming EPROMs for your application. Unreliably programmed parts could get someone killed, so you need to program them correctly. This means programming at VCC=6V and blank verifying at VCC=4.5V. Most Willem-based programmers won't have enough VCC options unless you modify them. I haven't figured out how to do this on the enhanced universal programmer (no schematic or component diagrams available).

trip0six Posted - 01/30/2006 : 18:40:03
Also my ID setting in toolbar is GREY, unless I choose another type of chip in device. To verify I.D. and some chips verify fuji and some don't even I.D. Also in the list they dont have at27 to choose from only at29. If ene1 can step by step help me out and trouble shoot this. I learn fast but if your gonna get involved with helping me out please have patients. I tried jumper settings and bios settings, Have the write cables. "Not printer cable" I am not ignorant to a simple proccess and feel maybe its my system. Not Willem. Downloaded fix for WinXP. Thanks again!!!!!!!!!!!!!

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