f_lez
- 28th October 2009, 00:22
Ok 4mhz crystal, 18f2550, led...
basic program is simple enough
'
'
define osc 16
ADCON0 = 0
CMCON = 7
trisa=0
loop:
porta=255
pause 1000
porta=0
pause 1000
goto loop
'
'
'
and these fuses are in a p18f2550fuses.inc
CONFIG PLLDIV = 1 ; set for 4mhz to pll
CONFIG CPUDIV = OSC4_PLL6 ; set for 16mhz cpu core
CONFIG USBDIV = 2 ; usb=pll/2
CONFIG FOSC = HSPLL_HS
CONFIG FCMEN = ON
;
;
;
;
(other fuses omitted)
thing is i can set the define osc to whatever i want, the speed the led flashes at is not changed, i thought the define osc was used to re-compile the delays etc in the pause routines? (amongst other things)
why do i not see a speed change in the led when i change it, why do i not see one second on and one second off, its more like a 1/4 of that irrespective of setting of define osc
I can set the fuses for the chip by hand at burn time, so i know the fuses are burned correctly as if i do set them by hand, same result, also if i set them wrong i can get faster flashing, but i cant get it to slow to 1hz irrespective of cpudiv/osc etc, i seem to get 2/4/8hz
basic program is simple enough
'
'
define osc 16
ADCON0 = 0
CMCON = 7
trisa=0
loop:
porta=255
pause 1000
porta=0
pause 1000
goto loop
'
'
'
and these fuses are in a p18f2550fuses.inc
CONFIG PLLDIV = 1 ; set for 4mhz to pll
CONFIG CPUDIV = OSC4_PLL6 ; set for 16mhz cpu core
CONFIG USBDIV = 2 ; usb=pll/2
CONFIG FOSC = HSPLL_HS
CONFIG FCMEN = ON
;
;
;
;
(other fuses omitted)
thing is i can set the define osc to whatever i want, the speed the led flashes at is not changed, i thought the define osc was used to re-compile the delays etc in the pause routines? (amongst other things)
why do i not see a speed change in the led when i change it, why do i not see one second on and one second off, its more like a 1/4 of that irrespective of setting of define osc
I can set the fuses for the chip by hand at burn time, so i know the fuses are burned correctly as if i do set them by hand, same result, also if i set them wrong i can get faster flashing, but i cant get it to slow to 1hz irrespective of cpudiv/osc etc, i seem to get 2/4/8hz