On Wed, Dec 08, 2004 at 08:23:15PM -0500, John J. McDonough wrote: > ----- Original Message ----- > From: "Ralph Seguin" > Subject: [PIC] HELP!! PIC 16F88, Olimex PG4-D, Newbie problems... > > > > Set of sample programs for the 16F88? 16F877A (which I'm going to > > stick on an Olimex P40-B)? > > Ralph > > I should have caught this one earlier, too. The 16F84A programs almost > identially to the 16F84. However, the 16F877A programs entirely differently > than the 16F877, so don't get caught in the same problem when you move to > that chip. It's not entirely different. All of the newer chips in the 16F family, and all 18F chips IIRC, do block writes. So you have to write a group or 4 or 8 consecutive words if you want it to program properly. Also each chip has a slightly different algorithm for erasure. The upshot is that you generally cannot simply switch from one programming algorithm to another blindly without consequences. > > There are a handful of different programming algorithms, but basically the > older parts program one word at a time. For larger memories this gets slow. > So on the newer parts, they are programmed four words at a time. The 88 and > 877A are this way, but the 84A and 877 are not. A lot of the older > programming software only knows the old way. Bingo. BTW I believe the 877A is 8 words writes. > > There actually is a tiny difference in programming between the 84 and the > 84A, but it's so tiny that a programmer would have to work hard to write > software that would work on one and not the other. But the difference > between the 877 and the 877A is night and day. Not night and day, but sunrise and sunset. You can generally get away with programming a 16F877A with the 16F877 algorithm if you write the entire memory. BAJ _______________________________________________ http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist