Setting BOR Enabled

JerryR · Joined: 07 Feb 2008 Posts: 167

I am having a problem enabling BOR at 4.5 volts on a PIC18F4525. Using CCS PCWH 4.121 with MPLab 8.70 IDE. IDE in Release mode and compiled code. Flags set as below:

edmundopt · Joined: 08 Dec 2011 Posts: 15 Location: Portugal

maybe use

JerryR · Joined: 07 Feb 2008 Posts: 167

edmundopt: Thanks for your reply. BOREN is not a valid flag for the PIC18F4525, and indeed it does produce a compiler error.

Anyone else have a suggestion? Is there a document anywhere that explains the CCS fuses?

Thanks

drh · Posted: Sun Dec 11, 2011 8:52 am

These are the brown out fuses for that device.

NOBROWNOUT, BROWNOUT_SW, BROWNOUT_NOSL
BROWNOUT, BORV45, BORV27, BORV20
_________________
David

JerryR · Joined: 07 Feb 2008 Posts: 167

Thanks for the reply David

Yes, I see these combinations in 18F4525.h. However, no combination of these bits enable brown-our reset at 4.5 volts. This is confirmed by viewing the configuration bits in MPLAB after compiling in RELEASE mode. MPLAB reports:

BOREN Brown-out reset disabled in hardware and software
BORV Maximum setting

I have been having problems with an old project where EEPROM is being corrupted on either power-up or power down. Brown out reset should fix the problem and I can't enable it.

I would like to enable BOR at 4.5 volts with flags. Shouldn't the following combination provide this?

Ttelmah · Joined: 11 Mar 2010 Posts: 19515

You need to get rid of the ICD=TRUE in your code, as well as changing to release mode.

#FUSES BROWNOUT,BORV45

is the correct combination, and does work.

Get rid of *=16. This only applies to PIC16 chips.

Best Wishes

JerryR · Joined: 07 Feb 2008 Posts: 167

Ttelmah:

Thanks for your reply. I'll give that a try.

All the best