18F4515 fuses and oscillator

Guest · Posted: Tue Jan 31, 2006 6:38 am

Can anyone point me to a document that describes the fuse constants and oscillator setup for the 4515? I want to run with a 10MHz crystal and the PLL enabled.

Thanks.

ckielstra · Joined: 18 Mar 2004 Posts: 3680 Location: The Netherlands

Check the top of PIC18F4515.h for all allowed fuse settings.
A description of the fuse acronyms can be found in fuses.txt in your PICC directory.

More detailed info on the fuse settings is in the Microchip PIC18F4515 datasheet.

For 40MHz operation you use a 10MHz crystal and the H4 fuse setting.

Guest · Posted: Tue Jan 31, 2006 10:46 am

Thanks, I have it running. The fuses.txt file was the thing I missed.

Ringo42 · Joined: 07 May 2004 Posts: 263

Is there a way to use a 20Mhz crystal and use a 2X PLL? I didn't see the option in #fuses but want to make sure. Also to use the 4Xpll is this how you do it?

#fuses h4,nowdt,noprotect,put,lvp
#use delay(clock=10000000)

Ringo
_________________
Ringo Davis

Ttelmah · Guest

Look at the chip's data sheet. The only PLL available for the external oscillator is *4, hence the lack of fuses for anything else...
No, the setup for a 10MHz cystal, running with the PLL at 40Mhz, would be:

#fuses h4,nowdt,noprotect,put,lvp
#use delay(clock=40000000)

The setting you give would be for 2.5Mhz *4, which is an invalid configuration for the HS oscillator.

Best Wishes