source= http://www.piclist.com/postbot.asp?id=piclist\2001\05\29\214033a Not to minimize the problem, but I think people are overstating this issue of haveing to multiplex each target pin on a "universal" programmer to 5, 10, 100 etc... different sources. Yes, each target pin could need to be high, low or floating and the high and low need to be from the target power for in circuit programming. Any uP (e.g. a PIC) can do standard logic levels and tri-state its pins so that takes care of that one. Devoting a target powered big fat PIC (or two or more as needed) to that should work nicely. Or several pairs of shift registers with one feeding the inputs of a tri-state buffer and the other feeding the output enables. Then you need a programming voltage which can be, as pointed out, +6, +12, +13, +21.5 and a whole bunch of other possibilities, but I don't believe I've ever seen a case where you need more than one "programming voltage" at a time, and I don't remember ever seeing that it needed to be applied to more than one pin at a time. Tony's Pocket implements an idea from the CUMP project to produce a PIC controlled voltage source using only a few components. Routing it to the appropriate pin could be accomplished by any number of techniques: A) PCB adapter cards (ala the Needhams EMP-20 simm card) in the CUMP project, this was more or less built into the adapter "daughter boards" for each family of processor since they tend to be very simular in each family. B) a simple rotary switch to be manually set by the user as instructed by the programmer. I'm sure that turning a switch is not to much to ask of an operator? C) Finally, as a fun, Rube Goldburg solution, why not mount a wiper on a block of wood riding over a set of PCB pads on a threaded rod connected to a small motor? My dad did just that for a testing machine that was used by telephone switching manufacturers to check the old rotary stepper switches used in central exchanges. And don't give me the "unreliable contact" argument. Multiple strips of spring steel with a sharp nub punched in the wiper end WILL get you a reliable contact. Any any case, the number of adapter PCBs or poles on the rotary switch, etc.. can be limited by carefull selection of the required insertion position of the target. This is what Tony's pocket and many other programmers do. I'm really interested to hear the arguments either way WHEN they teach us something about the difficulties encountered or the solutions available with this type of problem. Lets keep learning even if the result is "rediculous" or not commercially "realistic" And Dan, I would really appreciate it if you would consider that we have all heard your complaints about the CUMP project now. We get that you were hurt, and I, for one, am sorry that you didn't profit from the time you spent on it. You have had your say and thank you for warning people that open source development and learning are not always commercially profitable and often do not produce any results. Now, I would like to get on with learning about programmers and how to implement them with PICs. I was very happy with what was learned while the CUMP project was active and the good suggestions (and there were many) that came out of it. Also, for any commercial programmer vendors who enjoy laughing on the list at those of us who are interested in spending some time learning about how you do your thing, I'm sorry if you feel threatened or just wish to discourage people from learning in this area. I don't begrudge or disparage your PIC related products or business and I want to do anything I can to support them (tell me how) but please don't disparage our desire to learn. It is not based in a desire to destroy you. I hear good things about the Xeltek Unipro and would like to recommend them on the web site, but I don't seem to be able to find any current source. Did they go out of business? --- James Newton, PICList Admin #3 mailto:jamesnewton@piclist.com 1-619-652-0593 http://www.piclist.com/member/JMN-EFP-786 PIC/PICList FAQ: http://www.piclist.com -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body