----- Original Message ----- From: "Ken Pergola" To: Sent: Thursday, August 28, 2003 10:08 PM Subject: Re: [PIC:] 18f1220 xtal osc. > Hi George, > > Sounds like you still have some strange behavior with your project, yes? > > Yeah, you have to keep the 'scope's loading effects in mind when probing the > OSC pins. In case you might need to gauge the accuracy of your crystal (say > in the future or something), you can always spit out a PWM signal via the > hardware CCP and measure that signal -- at least it will not load down the > oscillator circuit and affect the frequency (load-pulling). > > If you haven't already, you might want to download the PIC18C Reference > Manual (DS39502A) from Microchip's web site. Check out section 2.10 on page > 2-24. Actually, all of Section 2 is on the Oscillator. > Hi Ken, I have a printed version and studied the osc section. The symptoms are what you would expect if the osc is not running, ie all i/o's high impedance, no outputs etc. what I don't understand is that the watchdog is enabled, surely it should cause a reset? Mclr is only connected to the icsp header and is disabled, though I have since redesigned it with microchip's reccomended circuit. I have just got back from delivering the artwork to the pcb guy and will get it back over the week end so that I can try it. Exact frequency is not too important, it is driving a sort of 26khz igbt inverter consuming about 8A from 230Vac, and as it is resonant, has to syncronise the igbt drive signals. George -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu