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18LF2520 Crystal

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camerart

Active Member
Hi,
Looking at the Data sheet for 18LF2520 PIC, it shows the highest speed crystal as 25MHz. I only have 32MHz, will they work ok?
Camerart.
 

Ian Rogers

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Most Helpful Member
I don't think so.... The max speed of this is 40Mhz but 10Mhz (4x) PLL.. So 32Mhz should only be an 8 Mhz crystal with the PLL..

I don't think a 32Mhz crystal would stabilize.... This is just in my opinion...
 

camerart

Active Member
I don't think so.... The max speed of this is 40Mhz but 10Mhz (4x) PLL.. So 32Mhz should only be an 8 Mhz crystal with the PLL..

I don't think a 32Mhz crystal would stabilize.... This is just in my opinion...
Hi R,
Ok, that's a shame. Anyone want 20x32MHz crystals? :)
C.
 

camerart

Active Member
Hi,
On re-reading the Data sheet, I think the PIC will work without a crystal.

I've tried setting OSCCON and PLL, but 18LF2520 does appear to be running correctly. Can anyone supple the OSCCON and PLL settings for 8MHz and X4 please.
C
 

Ian Rogers

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Forum Supporter
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You need to set OSCCON to 0x70 ( 8Mhz) and set the PLL bit in the config register.. I think there is a software bit aswell.

So config FOSC= INTIO2 and PLLEN = 1

Then OSCON = 0x70
Then OSCTUNE bit 6 needs to be 1.
 

jjw

Member
Hi I,
I think I've got it set correctly, but it's too fast.

Can you try it in the simulator please. The SIM is a bit faster than the PCB, but still shows too fast.

There is no INTIO1 and 2 option. I used this:

Thanks, C.
What is too fast?
Waitus 1000?
Define clock_frequency 8 -> change to 32
 
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