18f2550 oscillator problems

[rjones2102]

Hi all,

I am running an 18f2550 using internal oscillator. I have a timing problem that causes the program to run what I believe is 4 times slower than it should.

I have the following fuses set in 18f255.inc in the PBP directory.

__CONFIG _CONFIG1L, _PLLDIV_1_1L
__CONFIG _CONFIG1H, _FOSC_INTOSCIO_EC_1H
__CONFIG _CONFIG2H, _WDT_ON_2H & _WDTPS_512_2H
__CONFIG _CONFIG3H, _PBADEN_OFF_3H
__CONFIG _CONFIG4L, _LVP_OFF_4L & _XINST_OFF_4L

I have the following code running on chip.

OSCCON=%01100000
DEFINE OSC 4
TRISA=%0000000
ADCON1 = 7 ' A/D off, all digital
high PORTA.5
pause 1000
low PORTA.5
pause 1000
high PORTA.5

I am sure the LED on PORTA.5 is staying on for 4 seconds and then goes off for 4 seconds before finally coming back on. What am I doing wrong?

[rjones2102]

Sorry, I should also have said I am using MPASM

[Ronald123]

Hi,

Try to set de _PLLDIV_1_1L to _PLLDIV_5_1L. This is also the setting when I'm using USB on the 18F2550 with a 20MHz oscillator.

Regards,
Ronald.

[mister_e]

i'll bet on

        __CONFIG _CONFIG1L, _PLLDIV_1_1L & _CPUDIV_OSC1_PLL2_1L

[mackrackit]

INTOSCIO ??? How about INTCKO instead.

Try -- OSCCON=%01111100

[mister_e]

INTCKO is not a valid fuse in my current MPASM version (5.11) for the 18F2550

;----- CONFIG1H Options --------------------------------------------------
_FOSC_XT_XT_1H       EQU  H'F0'    ; XT oscillator, XT used by USB
_FOSC_XTPLL_XT_1H    EQU  H'F2'    ; XT oscillator, PLL enabled, XT used by USB
_FOSC_ECIO_EC_1H     EQU  H'F4'    ; External clock, port function on RA6, EC used by USB
_FOSC_EC_EC_1H       EQU  H'F5'    ; External clock, CLKOUT on RA6, EC used by USB
_FOSC_ECPLLIO_EC_1H  EQU  H'F6'    ; External clock, PLL enabled, port function on RA6, EC used by USB
_FOSC_ECPLL_EC_1H    EQU  H'F7'    ; External clock, PLL enabled, CLKOUT on RA6, EC used by USB
_FOSC_INTOSCIO_EC_1H EQU  H'F8'    ; Internal oscillator, port function on RA6, EC used by USB
_FOSC_INTOSC_EC_1H   EQU  H'F9'    ; Internal oscillator, CLKOUT on RA6, EC used by USB
_FOSC_INTOSC_XT_1H   EQU  H'FA'    ; Internal oscillator, XT used by USB
_FOSC_INTOSC_HS_1H   EQU  H'FB'    ; Internal oscillator, HS used by USB
_FOSC_HS_1H          EQU  H'FC'    ; HS oscillator, HS used by USB
_FOSC_HSPLL_HS_1H    EQU  H'FE'    ; HS oscillator, PLL enabled, HS used by USB

and the OSCCON was right in the first post.

Sorry mackrackit