Thanks. Jim Robertson wrote: >> >>> Bob Axtell wrote: >> >>> >> >>>> The programming algorithms for the PIC's have gained tremendous >> >>>> complexity >> >>>> (needlessly so, methinks) and those parts require a completely new >> >>>> approach >> >>>> in order to program them. > > > Bob, The parts the original poster was talking about were the 16F870 > and 16F777. The > algorithms for these flash parts are among the very earliest. The '870 > is part of the 87x > family and these were the second family of flash PICs, the 16[C/F]84 > being the first. > > The 16F777 algorithm is exactly the same as the 16F7x and again, these > are some of the > earliest flash PICs. So, "those parts" don't require "a completely new > approach in order > to program them." They require the older algorithms. > > >> >>> I think the reason for the increased programming complexity >> >>> is the effort to speed up the process. By a factor 8 in the >> >>> case of the 'A' v.s. non 'A' parts. > > > For the 16F87x Vs 16F87xA this is right of course but don't tie the > improvement to 'A' Vs > non 'A' as it is not always true. Let's just say Newer Vs older > algorithms. > >> As PIC flash capacity >> >>> increases, do you really want to wait 655 seconds (11 minutes >> >>> for 10msec/location) for a 65k word part? >> >>> >> >>> I can live with a more complex algorithm if it saves me 10 >> >>> minutes programming time. >> >>> >> >>> Robert >> >> >> >> Very good point, Robert. But look at the PIC18F "advances"; it >> >> takes 15 payloads to send a single word. Nothing faster about >> >> that scheme. Looks like it was developed after hours at Hooter's. >> > >> > >> > Really? >> > >> > >> http://ww1.microchip.com/downloads/en/DeviceDoc/30499b.pdf >> >> > PIC18F6X2X/8X2X >> > >> > "All instructions are 20 bits, consisting of a leading 4-bit > > > snip... > > >> > Doesn't seem THAT bad. >> >> Its worse. >> >> > " >> > Typically, all of the program buffers are written in parallel >> > (Multi-Panel Write mode). In other words, in the case >> > of a 64-Kbyte device (8 panels with an 8-byte buffer per >> > panel), 64 bytes will be simultaneously programmed >> > during each programming sequence. >> >> But each one of those 64 bytes, being unique, have to be >> shoved into a buffer to be written. 20bits per pop. Plus all >> of the table setups. Takes about 15 20-bit writes for each >> word written into the PIC18F device. There's not any savings >> anyplace that I can see. >> >> MY math says it takes about 8x what it does to write the >> same amount of PIC16F data word. > > > Bob, you math sucks! It is nothing like 8x the overhead. It takes 80x > 20 bit shifts to > load and program 8x8 panels (64 bytes) worst case. There is no begin > program > command required, no end program command required and no address > increment > either. Also, there is no start and stop bit required as for the PIC16 > family. > > It takes 22 clocks to load ONE 14-bit word on the 16F and this is NOT > including > begin and end programming commands and address increment command. > > My Math: > > 18F252: (32 * 20) + (8 * 6 * 20) = 1600 clocks + 1x prog time. > 16F877A (32 * (6+16+6)) + (8 * (6+6) ) = 902 clocks + 4x prog time > > (You could score a win on the extra brackets, or are they braces?) > > Anyway, bottom line times from a nameless USB programmer: > > 16F877A (8k x 14-bit) chip erase, code, ID, Config program = 3.6 > seconds > 18F252 (16k x 16-bit) chip erase, code, ID, config program time = 3.1 > seconds > 18F8722 (64k x 16-bit) same deal as above = 6.12 seconds > > Notice that the 18F8722 is 4x the size of the 18F252 > but takes less than HALF the program time. Role on > microchip advances. Another beer please Mr. Hooter. :-) > >> snip.. >> > I didn't realize the 18F was 32 times more efficient >> > at writing. And so what if more commands are required? >> > They're sent at megahertz, not the 100 hertz of programming >> > time. >> >> I didn't either. Megahgertz? Gosh, I gotta get better glasses... > > > And calculator too... > > Regards, > > Jim Robertson > NEWFOUND ELECTRONICS > > > > -- Note: To protect our network, attachments must be sent to attach@engineer.cotse.net . 1-866-263-5745 USA/Canada http://beam.to/azengineer -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist