Modern CPU clock multipliers

Sceadwian

Banned

• May 3, 2007

• #1

Can anyone provide any links for the operation of a modern CPU's clock generator? I'm asuming there's some sort of base crystal frequency on the board and then it's sent through a PLL synthesizer that's made for high numbers of multiplication.

 

ericgibbs

Well-Known Member

Most Helpful Member

• May 4, 2007

• #2

hi,
The 18F452 datasheet gives a brief description of its internal PLL.
[Just in case you did'nt already know.]


**broken link removed**

 

Last edited: May 4, 2007

gramo

New Member

• May 4, 2007

• #3

Here's an example of setting up the internal OSC and 4*PLL for most 18F PIC's with Swordfish

Code:

Device  = 18F4520
Clock = 32
Config OSC = INTIO67

OSCTUNE.6 = 1                   // Enables PLL

OSCCON = %01111111       // Sets up the internal oscillator

'
'
' Continue with progam

Note - You must define the Clock speed to be 32 not 8 as PLL is used! This will ensure the compiler generates the right delays for other functions/procedures

 

gramo

New Member

• May 4, 2007

• #4

The config;

Code:

Config OSC = INTIO67

Makes PORTA.6 and PORTA.7 normal I/O's when the internal OSC is used

 

evandude

New Member

• May 4, 2007

• #5

No offense, but what does a walkthrough of configuring a PLL in a microcontroller in BASIC have to do with the OP's original question about the hardware used in clock generation for modern CPU's??

 

gramo

New Member

• May 4, 2007

• #6

evandude said:

No offense, but what does a walkthrough of configuring a PLL in a microcontroller in BASIC have to do with the OP's original question about the hardware used in clock generation for modern CPU's??

Click to expand...

Nothing really, I guess I miss read it