I picked us a dozen of these really cheap and figured I would make a programmer for them. This family of chips uses a 10-bit serial command (at 2Mhz) to select the different program modes of the chip (read, verify, encrypt, security, and signature (chip type).. I searched the internet and couldnt find any programmers out there. So I designed one myself based on the 87c751 data sheet information.
It turned out to be fairly complicated but I completed the programmer, which is driven by the parallel port of a PC. It provides the required input signals as specified by the data sheet. But I dont believe the serial command sequence is working. Before trying to burn code into one I figured I would just try to read the signature byte. An operation that is relatively simple. Just send a 294h serial command to the reset line, present a 1Eh to the address line, and read the data which should be 9Fh for the 87c751.
Does anyone have experience with the 87c75x series processors? I have a few questions... Has anyone seen a programmer design for them? Could you point to it or post it here. If someone would like to see it, Ill post my design here, I used ExpressSCH, converted to PDF's.
Thanks
Aule
It turned out to be fairly complicated but I completed the programmer, which is driven by the parallel port of a PC. It provides the required input signals as specified by the data sheet. But I dont believe the serial command sequence is working. Before trying to burn code into one I figured I would just try to read the signature byte. An operation that is relatively simple. Just send a 294h serial command to the reset line, present a 1Eh to the address line, and read the data which should be 9Fh for the 87c751.
Does anyone have experience with the 87c75x series processors? I have a few questions... Has anyone seen a programmer design for them? Could you point to it or post it here. If someone would like to see it, Ill post my design here, I used ExpressSCH, converted to PDF's.
Thanks
Aule