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