Post by thread:Oscillator Running?

cdupuy wrote: > > I have a 4mhz crystal attached to an 16f84 (pin 15 & 16). > I am having a problem picking up TMR0 interrupts. > Program appears to work fine in the simulator. > Is there a way to tell with only a DMM if the osc. is running? I think that looking at OSC2/CLKOUT (pin 15) with a x10 probe is best. Michael * TAKE THE '.NOSPAM' OUT OF MY ADDRESS TO REPLY ********************************************** Outside of a dog, a book is man's best friend. Inside of a dog, it's too hard to read anyway! Groucho Marx **********************************************

Michael J. Ghormley wrote: > > cdupuy wrote: > > > > I have a 4mhz crystal attached to an 16f84 (pin 15 & 16). > > I am having a problem picking up TMR0 interrupts. > > Program appears to work fine in the simulator. > > Is there a way to tell with only a DMM if the osc. is running? > > I think that looking at OSC2/CLKOUT (pin 15) with a x10 probe is best. > > Michael If you can connect a spare inverter (7404 or the like) on OSC2, use a pullup of course if that's an OC inverter, you should be able to use that as a buffer & read about Vcc/2 at the output (referenced to either Vcc *or* ground), with just a DVM (I haven't tried this yet, but I've planned to get to it. It's sure worked in many logic circuits I've worked with before!) I assume a 50% duty cycle for OSC2, but IIRC that's the right number <G> A buffer or spare J-K flip flop or whatever would work as well. Also a 4 MHz Shortwave receiver, or a frequency counter, if you have one of those handy <G> Mark Keeping leads short between the PIC and the inverter's input here would be a *good* idea, but I don't know of other problems than that

Michael J. Ghormley wrote: > cdupuy wrote: >> Is there a way to tell with only a DMM if the osc. is running? > I think that looking at OSC2/CLKOUT (pin 15) with a x10 probe is best. Mmm, if you count a Fluke Scopemeter as a "DMM". Actually, you don't really want the DMM at all. You want a LED connected to one port (pin) with a 220 ohm resistor, and a test program which generates a 1Hz flash on that port using no WDT, no interrupts, just program loops. The program WL84.HEX might be of use. See: http://www.dontronics.com/dt001cha.html#testing First rule; start simply. -- Cheers, Paul B.

Hi, I haven't tried this but it will maybe work. Put a series capacitor on the OSC2 pin (about 100pf) and set your DMM to AC voltage reading. Most DMM's have high impedance input so this may work. If you got a voltage reading, the oscillator is working. regards Reggie cdupuy wrote: > > I have a 4mhz crystal attached to an 16f84 (pin 15 & 16). > > I am having a problem picking up TMR0 interrupts. > > Program appears to work fine in the simulator. > > Is there a way to tell with only a DMM if the osc. is running?

Hi, have you grounded both pins with a 22 pF capacitor? Imre On Thu, 7 Jan 1999, cdupuy wrote: > I have a 4mhz crystal attached to an 16f84 (pin 15 & 16). > > I am having a problem picking up TMR0 interrupts. > > Program appears to work fine in the simulator. > > Is there a way to tell with only a DMM if the osc. is running? > >