All Forums  MCUmall Forums  True USB Willem Programmer (GQ-2X,3X,4X & GQ-4x4)  More issues with M87C287 devices?

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Screensize: 640 x 480 800 x 600 1024 x 768 1280 x 1024 UserName: Password: Format Mode: Basic  Help  Prompt  Format: Font Andale Mono Arial Arial Black Book Antiqua Century Gothic Comic Sans MS Courier New Georgia Impact Lucida Console Script MT Bold Stencil Tahoma Times New Roman Trebuchet MS Verdana   Size 1 2 3 4 5 6   Color Black Red Yellow Pink Green Orange Purple Blue Beige Brown Teal Navy Maroon LimeGreen Message: * HTML is OFF * Forum Code is ON Smilies [quote][i]Originally posted by vibroverbus[/i] [br]Having trouble writing M87C287's and I see searching the forum a number of others have had difficulty with these chips as well. Devices: M87C257-20XF1 & 20F1 Programmer: GQ-4X Software: v.6.13 and v.6.14 Power: AC External power supply & voltage tests good I have 20 supposedly "new ST brand" devices to test, 10 each from 2 different sources, and out of those only could successfully write 2 using the default settings. I was able to write 2 more using the M27C256B definition which has a very similar datasheet but lacks the latching feature. Failures are 90% during the write, 10% of the time the write completes but fails in final verify. When reading Device ID on these chips using M87C287 setting, "FFFF" is returned which seems like a failed ID read process. When reading a blank using the M27C256B settings, "8080" ID is returned which is invalid but nonetheless seems better. Other old legacy M87C257 EPROMs I have DO successfully read a good ID using normal M87C287 settings however none of these "new" chips seem to read the ID with the M87C257 device settings. The real ST datasheets for both devices seem to indicate the exact same procedure for interrogating Device ID so not sure understand why this is different. I have customized devices.txt entries for these devices to ensure the voltages match datasheet and I am using lines as follows: ;******** Name="M27C256B#2",ID="9B04",Class="27C256",Category="EPROM",MFG="ST",VCC="5V",WVPP="12.7V",WVCC="6.2V",BVCC="6.2V",RVPP="5V",Speed="5"; //by JC ;******** Name="M87C257#2",ID="2080",Class="87C257",Category="EPROM",MFG="ST",VCC="6.2V",WVPP="12.7V",WVCC="6.2V",BVCC="6.2V",RVPP="5V",Speed="3"; //by JC ;******** Questions: - Why does ID come back differently for different devices when datasheet indicates same procedure? Is there an error in the algo for the M87C257? - Could these chips be fake re-labeled and actually be something else? They work in my application WHEN they burn so if there is a better device selection to try that would work it would be great. [/quote]    Insert an Image File Check here to include your profile signature.