Oscillator PICmicro Microcontroller

[r2d2droids]

hi all,
"The HS oscillator is designed to give the maximum gain and frequency response. The current consumption is accordingly higher. The gain is roughly five times higher than that of the XT oscillator. This gives the PICmicro the ability to operate at frequencies up to 20 MHz."

is it means, i must apply OSC1 input about 80MHz external clock cycles in order to operate PICmicros at 20MHz?

 

[aland]

Hi, what PIC?

Some divide extenal osc by 4, some take external osc and multiply it through an internal PLL by 4. but I think the highest clock I've seen on a PIC is 40MHz, so I'm taking an educated guess that your PICs Maximum is 20MHz divided by 4 to give an internal clock of 5MHz.

You may also need to set bits to select different clock sources.

Apart fom the earlier RISC PICs where one external clock matched one internal clock other PIC's depend on the actual PIC. Have a closer look at Microchips site.

 

[VVV]

The maximum oscillator frequency is 20MHz. Some parts have an internal PLL, which allows them to work at up to 40MHz internally.
However, one instruction cycle takes 4 oscillator periods, so if the part is running at 20MHz clock, the actual instructions execute at 5MHz (except goto's).
That gives you the 200ns/ instruction time (1/5MHz=200ns) or 100ns (1/10MHz=100ns). In the latter case, the core is running at 40MHz clock, divided again by 4.

 

[r2d2droids]

the PICmicro is PIC16F877. how to operate this PICmicro about 20MHz core frequency? is it possible?

 

[KST]

the PICmicro is PIC16F877. how to operate this PICmicro about 20MHz core frequency? is it possible?

Haven't got any PIC16Fxxx or 18Fxxxx with 20MHz (Mbps) core. Max = 12 Mips (18F2550/4550, . . . )
PIC24Fxxxx has got 20Mips core 16 bit.
Good luck for U !

 

[aland]

Not possible to put this PIC on roids.

8 bit micro, DC to 20MHz external, 5MHz internal.

 

[r2d2droids]

ok. i got it.
thx for all replies

 

[sarin]

can i use some other microcontrollers using the same idea