Using PLL with an external crystal oscillator

[kgng97ccs]

I am using PIC18LF46K22, CCS C compiler v5.078, and MPLAB IDE v8.92.

Section 2.8.1 (PLL IN EXTERNAL OSCILLATOR MODES) of the PIC datasheet says that “The PLL can be enabled for any of the external oscillator modes using the OSC1/OSC2 pins by either setting the PLLCFG bit (CONFIG1H<4>), or setting the PLLEN bit (OSCTUNE<6>). The PLL is designed for input frequencies of 4 MHz up to 16 MHz …”

I tried to set up PLL with an external 16-MHz crystal oscillator with this code:

[Ttelmah]

The reason it complains is that the PLL cannot do *2. Look at the datasheet
and the clock section _*4 PLL_. Not *2.

So:
#use delay(xtal=16MHz, clock=32MHz)

Can't be done.

#use delay(xtal=16MHz, clock=64MHz)

Can

[kgng97ccs]

Thank you, Ttelmah, for highlighting that. I had misunderstood the 4xPLL to mean "up to 4x".

[Ttelmah]

On the DsPic'x, there are programmable PLL's. On the standard PIC's,
they are only fixed multiples...

[kgng97ccs]

Thank you, Ttelmah. It is good to know that.