After fixing a few crossed ICSP wires, the chip programs and verifies OK. Well, the plot thickens. I had a 4 MHz crystal and two capacitors (22 pF, IIRC), and still could not get my PIC to oscillate. I replaced the crystal and caps with a 4 MHZ packaged ceramic resonator with internal caps, and the oscillator strarts fine. So what causes one kind of crystal to not oscilate with the PIC, another to work OK? I've never really run into this before. --Lawrence ----- Original Message ----- From: "Lawrence Lile" To: "pic microcontroller discussion list" Sent: Thursday, June 13, 2002 8:55 AM Subject: [PIC]: Will an unprogrammed chip oscillate? > Will a fresh, unprogrammed chip oscillate if it is powered up? > > I have a circuit with ICSP that seems to have two problems - first I can't > get my programmer to successfully program it, and second, I don't find any > signal on the oscillator pins. > > The first problem is probably going to fall after I make a shorter > programmer cable, and double check all the connections, and remove some > capacitance that might be in the MCLR line. This has deviled me before. I'll > make sure the chip really has 5V and also double check all the wiring to the > PIC. > > Meanwhile, though, I expected the chip would oscillate by default, and I am > wondering if I should be seeing something on the OSC pins or not. I am > using a 4 MHz crystal, which should require the XT oscillator option. What > is the default oscillator fuse on a 16F73? > > > --Lawrence > -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.