16F876 : settings for 40Mhz

[mischl]

ok, i now have a 18f242 with the possibilty to clock with 40mhz. and i have read the manual with the pll section. now i know that i must configure something the FOSC bit to multiple with 4. how i do that exactly in PBPro or with a assembly line inside?

thanks a lot for an explanation. greetings from a geek

[mister_e]

you must se configuration fuse and add a DEFINE OSC 40 at the top of your code

look here to know how to define your config fuses

the end of your 18f242.inc file look like this

;Configuration Byte 1H Options
_OSCS_ON_1H        EQU  H'DF'	; Oscillator Switch enable
_OSCS_OFF_1H       EQU  H'FF'
_LP_OSC_1H         EQU  H'F8'	; Oscillator type
_XT_OSC_1H         EQU  H'F9'
_HS_OSC_1H         EQU  H'FA'
_RC_OSC_1H         EQU  H'FB'
_EC_OSC_1H         EQU  H'FC'	; External Clock w/OSC2 output divide by 4
_ECIO_OSC_1H       EQU  H'FD'	; w/OSC2 as an IO pin (RA6)
_HSPLL_OSC_1H      EQU  H'FE'	; HS PLL
_RCIO_OSC_1H       EQU  H'FF'	; RC w/OSC2 as an IO pin (RA6)

so _HSPLL_OSC_1H have to be choose

[mischl]

thanks for your support.

my file starts so :

@ __config _HSPLL_OSC_1H

DEFINE OSC 40


i compile with the mpasm and get this error message :
[126] .. : argument out of range (not a valid config register address)

[mister_e]

NOP.... Read the bottom of your .inc file. you must write...

@ __CONFIG _CONFIG1H, _HSPLL_OSC_1H
DEFINE OSC 40

what about now

[mischl]

first i got two error messages about "overwriting previous address content" which i fixed with comment out the line "_CONFIG1H......" in 18F242.inc from the PBP root.

for testing i work with a simple programm which blinking a led. it works..., but the pause command is 4 times slower then it should be. so, it seems the pic works with the 10mhz from the external oscillator, not with the 40mhz i wish.
in the melabs programmer i've set the oscillator to HS as HSPLL too for testing, the result is the same. what can be wrong again?

thanks a lot for a support

[mister_e]

That's strange. I'm not 100% of what i say but, looks like your programmer don't program the configuration bits for your device.

What's happening if you use a 20 MHZ oscillator and use HS mode???

what about now if you use a 4mhz and and use XT mode???

[Melanie]

Whether you set the config bits in your program or not, you should be capable of setting those bits manually prior to burning the PIC. If your programmer is incapable of doing that, you may need a sortware update for it, or alternatively you might need a better programmer.