Hi there,
I have a PIC18F4XK20 Starter Kit board (with a PIC18F46k20)
( **broken link removed** )
which has a 32.768kHz crystal connected to the T1OSO and T1OSI (Timer1) pins. My application needs either a 32Mhz or 64Mhz clock frequency, and has to use an external oscillator as it requires timing accuracy. To increase the crystal frequency, I had planned to use it with the PLL in HSPLL mode. However, I have read that this 'High Speed' mode will only work with crystals of 3-4Mhz or more, and so I'm guessing that I won't be able to run my 32kHz in this HSPLL mode. Is this true ?
Furthermore, from PIC MCU Clock Source Block Diagram it looks like the T1OSO and T1OSI pins (secondary oscillator) are not connected to the PLL, only the primary oscillator and internal oscillator. So it seems to me that I cannot use that board's crystal for my application after all; however I'd just like you guys to confirm my suspicions, as I'm not really familiar with oscillators and PLLs.
Thanks for you time.