#FUSES options

Ttelmah · Joined: 11 Mar 2010 Posts: 19828

Realistically, this is a 'read the data sheet' question.
Combined with what you actually want the chip to do.

WDT - enable the hardware watchdog. Generally actually using the watchdog usefully requires a lot more careful code than most people use.
<https://betterembsw.blogspot.com/2014/05/proper-watchdog-timer-use.html>

PROTECT - enables read protection of the chip's ROM. Only ever turn this on when your code is finished. Having this enabled, increases wear on the ROM when doing code development.

PUT - delays chip start to give time for a crystal to stabilise. Should be used if you are using a crystal.

BROWNOUT - enables brownout reset on the chip. If the supply droops below the point where the chip can actually work properly, ensures the chip physically resets.

Most modern chips will have hundreds more fuses than this. All are described in the data sheet, and this is why this is vital when working with any PIC. The fuses need to be set correctly if the chip is going to work as expected. The 'defaults; are rarely what is needed.

temtronic · Posted: Sun Nov 04, 2018 6:32 am

I've always had PUT enabled for all the PICs+, for all types of clocks. That extra 50-60ms doesn't really cost anything on 'bootup' yet helps ensure the PIC starts up properly.

The sad thing is there are so many Fuses ! I've had to make an 'include' file of all of them,in a KNOWN working configuration. It saves a lot of typing (2 fingers here, one 1/2 dead..). Remembering 30-35 instructions was easy, fuse not so much !!

Jay

Ttelmah · Joined: 11 Mar 2010 Posts: 19828

An early PIC like the 16F84, has a really low number of fuses (just 5 in this case). Modern PIC's, especially those supporting USB, can have a huge number. For example the PIC24FJ1024GA610, has 88. Some of the 'medium age' devices that have peripheral that are re-configured by the fuses, have even more. The highest number I have met is about 120....
It is always worth simply printing this part of the data sheet, and working through it marking the ones that need to be set. Then working out the actual values for all of them. As Jay says, making an include file with the settings you want for a project/chip is a very good way of handling this. Particularly since if you then do another project with the same chip this can simply be copied, and any small tweaks made for the new project....

dluu13 · Joined: 28 Sep 2018 Posts: 395 Location: Toronto, ON

I found a handy file in my "c:\program files (x86)\PICC" directory named Fuses.txt

It appears to be a comprehensive list of fuses, along with what each one stands for. The header file for your PIC will list what fuses are available for your device. These will just help you figure out what the abbreviations mean, but you should still check your datasheet to figure out what to do with them.