3/25/2021 0 Comments Eprom Programmer Kit
The datasheet says the chip can work with a pulse as small as 50nS.
![]() The kit arrived, very nicely presented with a clear double sided instruction sheet and a nicely laid out board with all the tracks on the back and a copper pour ground plane. I chose to fit an IC socket (I had already stolen the ZIF socket supplied with the kit for something else), as I wasnt planning to change the IC in it very often. Eprom Programmer Kit Code That DoesntWeve all had fun in the past with Arduino code that doesnt build and needs specific old versions of certain libraries, but I am pleased to say it built and programmed fine. The commands are detailed in the code, but basically V shows a version string, R aaaa reads from address 0x aaaa, and W aaaa: dd writes data 0x dd to address 0x aaaa (can be multiple bytes e.g. W aaaa: dddddd ). You can drive this from the serial monitor, but there are two provided front ends, a command line version and a desktop app. Yes, I have put labels on the chips, the etched labels can be tricky to read at some angles. No, of course my eyesight isnt getting worse, of course Im not getting old. I was able to read in data from the chip fine, but writing didnt seem to work. I checked with the author and he was using the same chips as me, and they were working fine for him. ![]() It was then I noticed the lines about Software Data Protection. Checking the AT28C64B datasheet, it seems there is a sequence of instructions that can be sent to the chip to lock it to disable future writes, and to unlock it again. My Minipro programmer was unlocking at the start, programming and then locking again. I tried removing the SDP (Software Data Protection, not the Social Democratic Party) and was then able to successfully program using the Arduino based programmer. There was no code present in there to do SDP which explains why it wasnt working on chips I had already used with my EPROM programmer. I had tried a chip fresh from the tube, but stupidly checked that it was working first by programming it on my EPROM programmer, which locked it. As there wasnt any provision for SDP in the code, so I tried enabling it using write instructions, W1555:AA, W0AAA:55 etc. Eprom Programmer Kit Series Of EventsChecking the datasheet, they specified a series of events, so I took the V0.01 code and built a V0.02 with SDP enable and disable built in, trying to follow this sequence. This didnt work either, I tried a few ways around it, but thought it may be timing related. The exiting code has an overly generous 10mS write pulse, which is actually the maximum the chip can support.
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