You are probably right- I was guessing. They are pretty cheap at hamfests but I suppose the could have run out in the surplus market. John Ferrell W8CCW "All that is necessary for the triumph of evil is for good men to do nothing." -- Edmund Burke http://DixieNC.US ----- Original Message ----- From: "PAUL James" To: "Microcontroller discussion list - Public." Sent: Tuesday, April 29, 2008 9:29 AM Subject: RE: [PIC] LED flash help > > John, > > 3.59Mhz as a watch crystal? I have never heard of this. Most of the > watch crystals I've seen have been 32khz. > The 3.58 mhz crystals (actually 3.579545 mhz) are for color burst in a > color TV. > > If there is a 3.59 mhz watch crystal, that must be some watch. > > > > Regards, > > > Jim > > > > -----Original Message----- > From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf > Of John Ferrell > Sent: Tuesday, April 29, 2008 7:49 AM > To: Microcontroller discussion list - Public. > Subject: Re: [PIC] LED flash help > > The led needs a series resistor to protect it and the processor from > over current. 330 ohms is popular there. > If the code works in the simulator the problem is nearly always either > in the configuration word or the clock circuit. > > I prefer crystals over resonators and 3.59 MHz watch crystals are pretty > cheap. > I Jameco to be the most complete vendor with the easiest catalog to deal > with. > There are smaller vendors who cost less and do a good job! > > I also prefer 4 AA batteries for bread board work rather than power > supplies. Less likely to toast something! > > John Ferrell W8CCW > > "All that is necessary for the triumph of evil is for good men to do > nothing." -- Edmund Burke http://DixieNC.US > > ----- Original Message ----- > From: "James Alspach" > To: "Microcontroller discussion list - Public." > Sent: Tuesday, April 29, 2008 12:26 AM > Subject: [PIC] LED flash help > > >>I have been lurking for a long time now and I finally bought a PICit 2 > and >> am excited to get past the first step...flash a LED. >> I decided to use a 16F628A partly because I did not have the parts >> available >> to add a clock (I am looking for a good place to buy low quantity > ceramic >> resonators hopefully with the caps built in). I used the 'simple' > sample >> program changing only the processor type. >> I put the chip on a solderless bread board and ran power to pins 5 and > 14 >> I >> also ran a wire from pin 8 to one side of an LED and from the other > side >> back to the power rail. >> I was able to program the chip successfully (the PICit recognized the >> chip, >> uploaded the program, and verified it.) but the LED does not light (on > the >> bb, the ones on the PICkit work just fine). I tried switching the > wires >> going to the LED in case I have the polarity wrong (unfortunately I >> removed >> this from an old CDROM and there is no flat side or longer lead) I > know it >> works though since I can quickly put it to the power supply and it > lights >> (This would tell me the polarity if I had thought to pay attention). > I >> also >> tried switching which rail I take the other side of the LED to > (positive >> or >> negative)..and then swapping the wires to the LED again. All to no > avail. >> >> Now for where I imagine the problem is coming in (let me know what you >> think). >> 1) I have not tied any of the other pins to anything. Can I tie them > all >> (selected pins?) to a resister and then that to the negative rail or > do I >> need enough resistors for every unused pin? >> 2) The power supply is an old Motorola cell phone wall wart charger. > It >> gives me about 4.6V @ up to 1.5 A but I have not put any caps > anywhere. >> >> I have read the FAQ's and searched online but am not sure where to > head >> next. >> >> Thanks for your help; >> James >> >> >> >> -- >>>From the desk of >> James, Melody, James and Savannah.. >> ...its a big desk. >> p.s. before you forward anything to us...please check www.snopes.com >> >> -- >> http://www.piclist.com PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist >> > > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist