PIC16f690 xtal for T1

Hello,

Is it legitmate to use an external xtal on osc1(RA5) and osc2(RA4) for Timer1s' clock source whilst at the same time using the internal RC oscillator as the main program clock source? I'm a tad confused after reading the data sheet.

Thus far on my current project I have used the internal oscillator at 8Mhz as the system clock and, connected to RA5 (T1CKI), an external clock derived from a HEF4060 driven by a 4.194304Mhz xtal. I want to do away with the 4060 if I can. Tried connecting a 32768Khz xtal to the pic but it won't run although I can get it to work on the 4060. So maybe what I'm trying is either 'illegal' or my configuration / setup is wrong.

Any help greatly appreciated, thanks in advance.

Works fine. The TMR1 osc is only rated for a 32,768 Hz crystal. Some older PICs went to 200kHz but if you want several MHz you need to supply it with a TTL level oscillator.

My Dragonfly kit uses a 32,768 crystal on TMR1, see the Dragonfly manual for schematics and source code for a clock.