GPS Project: PIC18F26K22 or PIC18F46K22

[Ioannis]

pause 10 is too little time.

Maybe you need to make this 1000.

Then check with a timer that it actually pauses every 1 sec confirming that osc is setup correctly.

Recently I had similar matter setting up system oscillator again with 4xPLL and was running slow. Richard got it and we are OK now.

Ioannis

[astanapane]

pause 10 is too little time.

Maybe you need to make this 1000.

Then check with a timer that it actually pauses every 1 sec confirming that osc is setup correctly.

Recently I had similar matter setting up system oscillator again with 4xPLL and was running slow. Richard got it and we are OK now.

Ioannis

Ioanni,

thanks a lot for the help. I'll do it tonight and try to increase the time.

To be honest i made many changing to the pause commands like : 10ms , 100ms, 1000ms, 2000ms. All seem to work fine.

It would be a good practice to see how could we identify that the PIC clock now is running at 64Mhz?

Is there any way to measure this with an Oscilloscope? I believe that this is a question have been asked many times.

If someone could help me to identify the cpu clock speed of the PIC with the new setting of external 16Mhz crystal and 4xPLL, i can do the testing, and share the information step by step in here. If there is already posted an example like this i would like to have a look at it.

thanks a lot.

[richard]

Is there any way to measure this with an Oscilloscope?

measure the led on/off time with the Oscilloscope if the osc is correct then the on/off times will be as per your code


I would leave CONFIG PWRTEN = ON


AND ADD THIS
OSCCON = %01110000 ; 64Mhz
OSCTUNE.6 = 1 ; Enable 4x PLL
while ! osccon2.7 :WEND

to make sure the pll has stabilised before you run any other code , if timing is critical

[astanapane]

measure the led on/off time with the Oscilloscope if the osc is correct then the on/off times will be as per your code


I would leave CONFIG PWRTEN = ON


AND ADD THIS
OSCCON = %01110000 ; 64Mhz
OSCTUNE.6 = 1 ; Enable 4x PLL
while ! osccon2.7 :WEND

to make sure the pll has stabilised before you run any other code , if timing is critical

Hi Richard,

Thanks, i will do that. So that means that the 8th Bit of the OSCCON2 which is the .7 must be presented?

[richard]

I seldom use crystals [you lose two pins for marginal increase in accuracy ] but I believe you can set pll mode in the config section and is all you need

CONFIG PLLCFG = ON
;CONFIG PLLCFG = OFF // pll can only be engaged with software selection for int osc


and then all this is not valid , it applies to internal osc only

OSCCON = %01110000 ; 64Mhz
OSCTUNE.6 = 1 ; Enable 4x PLL


this may or may not be necessary with xtal osc , I have found bootloaders won't sync up unless this is done using int osc with pll.
the PLLRDY bit is asserted when pll is stable [although I can find no mention in data sheet]
while ! osccon2.7 :WEND

[astanapane]

Hi Richard,

i got confused. Really im reading the datasheet and there is nowhere clear setting for using external crystal.

I came up with the following

OSCCON = %01110000 ; 64Mhz
OSCTUNE.6 = 1 ; Enable 4x PLL

Because i was thinking that in order to specify the OSCCON, and the multiplier PLL we need to add those lines even if it is for internal or external source. I didnt think that those where valid only for internal OSC.

So what should i add as OSCCON value, as i use and external crystal 16Mhz? How do i specify the OSCCON value for 64Mhz?

thanks once again. Apologize for all my questions.

[richard]

So what should i add as OSCCON value, as i use and external crystal 16Mhz? How do i specify the OSCCON value for 64Mhz?

nothing , leave it alone

OSCTUNE.6 = 1 ; Enable 4x PLL becomes non functional if CONFIG PLLCFG = ON