Bob Barr >Reply-To: pic microcontroller discussion list >To: PICLIST@MITVMA.MIT.EDU >Subject: Re: [PIC]: Newbie trying to get a 16f84_4 to work unsuccessfully >Date: Wed, 19 Sep 2001 12:54:58 -0400 > >William Cox wrote: >> >>Hi, I'm new to the PIC world. I do robotics. I've got a programmer (Tait >>style) from www.electronics123.com (P16PRO). I've got it working and I've >>programmed a PIC with the JAL code on this page >>(www.gorobotics.net/zac/ppu.shtml). I've also hooked it up according to >>the >>schematic on the above page (5.5v MCLR pulled high, resister through LED >>to >>GND, 24pF cap and 21k R/C oscillator) but it wont work (it's supposed to >>blink a LED). I think the problem is my oscillator. I'm not sure what >>values >>I should use. Right now I've modified the JAL library for the f84 to be in >>XT mode with a 2mHz clock. I'm using a 24 pF cap and a 21k resistor. That >>should give me ~2mHz right? I don't have a o-scope so I can see. Does >>anyone >>have any hints? Is there a good tutorial about getting a simple LED to >>blink >>on a x84 with a R/C clock? Thanks. >>-William >> > >Your R and C values appear about right but your mode needs to be set to RC >mode, not XT mode. I'll check the frequency on a breadboard that I've got >and get back to you with the value I read. > With a 22pf cap and a 22k resistor, I'm seeing about 280 KHz on CLKOUT. That's an Fosc of 1.12 MHz. Since you're using 2 more pF of capacitance and 1 less K of resistance, you're probably pretty close to your 2 MHz clock. YMMV. Regards, Bob _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads