-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 When I developed my '877 programmer, I used LEDs in the ICSP circuit so I could verify the operation of the programmer firmware. It turns out that I refer to them frequently as I download new software & activate the program, and I like having them in my design. The JDM programmer doesn't have enough umpf to power them from my serial port, so I have been working some in that area this week. I have made a preliminary SwitcherCAD model of the RS-232 driver circuit, the JDM programmer (in write mode), and my LED indicators. This is set up so that you can easily cut my portion of the circuit, and have a model for the JDM programmer. The voltage sources in the model are simply step supplies, each with twice the frequency as the one before, so that there is a binary counting sequence that represents all the possible input states. I modeled the RS-232 portion as +/- 10V into 1K ohms. This is almost certainly different from your own RS-232 port. It would also do for someone else to audit the JDM portion, to be sure that I haven't crossed something up. This SwitcherCAD file is available at http://www.jump.net/~vima/PIC/ICSP/icsp_02.asc The corresponding .pdf file shows some well behaved voltages with +/- 15 V RS-232 levels. A MPlab assembly file has some values of constants that tell when the circuit appears to be producing legal output voltages. This file, in the same directory, is states.asm and states.lst The next step to take is to compare the signal levels delivered to the JDM programmer by the IC-PROG software. If anyone has captured those voltages, I wish you would post them, as it would save me a couple of hours. One peculiar observation is that the voltages don't quite match the voltages I obtain on the bench, and that there are only two, not 4, legal programming states, so something is not quite right in the simulation or the analysis logic. - -- Aubrey McIntosh, Ph.D. -----BEGIN PGP SIGNATURE----- Version: PGPfreeware 7.0.3 for non-commercial use iQA/AwUBQAVc+gKlSw8yssF7EQLV2gCfaN9XYJB9zW2njYlBxbvSyPC2zxIAoLX2 nLZ3zDj5Q7FGFN2KiL53a3Ij =se5q -----END PGP SIGNATURE----- -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.