Thanks!!! FWIW, I am using it in HS mode.. that is correct isn't it? or should I be = in XT mode? Thanks, Des >>> dwayner@PLANET.EON.NET 12/03/03 7:07:31 am >>> At 06:10 AM 3/12/03 +1000, Des Bromilow wrote: > >>> "Des Bromilow" 11/03/03 8:48:14 pm >>> >G'Day, >My circuit with a 16F84a operating off a 4MHz crystal (with 2 x 33pF = caps) >doesn't seem to work on the most simple of programming tests. >I suspect my Crystal may be dead.. but I don't have a CRO to check, all I >have to test with is a Digital multimeter (DMM) >I would expect to see a 2.5 VDC voltage on OSC1, OSC2 due to the 5VDC >clock, and it's duty cycle. You can check the OSC2 pin with a multi-meter if you wrap one end of a = 100K resistor on the positive test lead and use the free end of the resistor to measure the DC voltage. It should be about 1/2 the supply voltage. The 100K resistor isolates the capacitance of the DMM and test leads from the crystal and allows it to continue oscillating (if it is). This same trick does not work on the OSC1 pin - even 100K load is usually too much. If it looks like an oscillator problem, try removing the crystal components= and configuring the PIC to use external RC oscillator mode. This requires connecting a resistor from Vdd to OSC1 and a small capacitor from OSC1 to ground. See the data sheet for the details. The accuracy is horrific but you can at least get a LED flashing. Then work back to using the crystal. One final thought - just for the heck of it, try changing from XT mode to HS mode before giving up on your current crystal configuration. dwayne -- Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 19 years of Engineering Innovation (1984 - 2003) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email. -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body