Actually, the 675 (or its cheaper brother the 629 or even cheaper cousin the 509) is perfectly fine for the task you described. I would not bother using the timer or interrupts. Just code the 38K generation in a timed loop. You can get 1/2 clock (2 Fosc) resolution by using n clocks high and n-1 clocks low. You can further tweak Fosc by playing with the osccal value. The good news is that most IR receivers are pretty forgiving of the exact frequency - most spec sheets I've seen show a couple of khz range centered around the frequency (38K in your case). Depending on your IR LED, you may be able to drive it directly from the PIC. I'd go up to 20 mA. Use a pin per LED if you need more than one. Of course, I'd be remiss if I didn't point out that a simple 555 timer would make an excellent beacon generator with a couple of Rs and Cs and can drive a lot more LED current. But then what's the fun of that? --- Tom Wrighton wrote: > Denny & Byron, > > Thanks very much for the response. I understand > that I am probably > setting myself up with a handicap by using the > 12f675, but that is > what I have so I'm trying it out first. I fully > intend to explore many of > the other features of the different PICs and I have > all the time in the > world, so I'm taking them one-at-a-time. Since I'm > in a robotics club > (www.chibots.org) I will be getting into PWM for > motor control soon. > After I get this project operating I intend to try > another (different) PIC. > Another response I got suggested using a ZTX > transistor to drive the > IR LED. I believe that to be Australian or > European. Does anyone > know what would be a good substitute available here > in the states. > Once I get comfortable with assembly, I will > probably swing over to > a version of 'C' which I used to do career wise > about fifteen years ago. > Of course there will be a significant relearning > process but I look forward > to it. I had better not drag this out. Again > thanks for the response and > looking forward to communicating on the list more in > the future. > > Best Regards, > > Tom > > Byron A Jeff wrote: > On Tue, May 03, 2005 at 04:02:36PM -0700, Tom > Wrighton wrote: > > > Hello All, > > Welcome Tom. > > > I'm a newbie, hobbyist, nonprofessional and > retired. I make these > > declarations up front so you might take my query > with a grain of salt. > > Must be nice. Hope you are enjoying it. > > > I?m still working on my 1st PIC project, though at > this point I feel I have > > learned a lot (for me anyway). I bought a PICkit-1 > after seeing it at one of > > our robot club meetings. As many of you know it > comes equipped with a > > 12F675. I have become obsessed with using it for > my project idea, and also > > to program it with assembly language. > > Both the part and the language could be problematic > if you're obsessed with > it. > > > [Snip of the issue. To much to do, not enough > time. ] > > > The best I can do so far is 32 and a fraction KHz. > > At this point I am wondering if I need to use a > crystal osc. And run it at > > 10 MHz instead of the 4MHz of the internal? I have > followed the PICLIST > > for several months and am very impressed with the > expertise and > > graciousness of the membership. > > Well that's certainly kind of you. Using the crystal > could help, and losing > the two I/O pins won't kill your project in this > case. > > > Up front: any and all comments and guidance you > might > > offer will be greatly appreciated. > > Well back to the obsession thing. I've been pointing > out to members on this > list that using hardware can simplify the life of > beginners. And I'm always > told that it's too complex. > > Your case is a perfect example. The PWM module on > other PIC chips are the > perfect set and forget tool required to get your job > done. A 16F88 would > solve the job easily with just a simple setup of the > peripheral. > > A quick poke around the pickit description doesn't > point to any parts that > has PWM built it. > > Finally on the language thing. Learn enough assembly > so that you can > communicate ideas with others in it. Then consider > higher level languages > simply because they facilitate setting up things > faster. > > Good luck on your project. And remember that PIC > hardware peripherals such > as the USARTS, PWM/CCP, ADC/comparators, and the > timers really are your > friends. > > BAJ > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > > > __________________________________________________ > Do You Yahoo!? > Tired of spam? Yahoo! Mail has the best spam > protection around > http://mail.yahoo.com > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist