What is the difference between processor clock and system clock?

Question

In the TM4C123G Launchpad Workshop page 129, there is a note about power modes. This note differentiate between processor clock and system clock. So what is the difference between them ? Is this a general concept or is it specific to the TM4C123GH6PM micro-controller ?

score 4 · Answer 1 · edited Dec 23 '14 at 16:45

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From the datasheet, the processor has a main clock, which the system clock is derived from as shown in the image below: enter image description here

edited Dec 23 '14 at 16:45

Some Hardware Guy

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answered Dec 23 '14 at 15:21

R Djorane

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Eugene Sh. · Accepted Answer · 2014-12-23T15:23:18.790

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The processor clock is derived from the system clock, but for the mode you are mentioning it is just "disconnected" from the processor core. So the system clock is not stopped (in the Deep Sleep it is stopped as well), it is just stopping feeding the core.

edited Dec 23 '14 at 15:23

answered Dec 23 '14 at 15:15

Eugene Sh.

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score 1 · Answer 3 · answered Dec 23 '14 at 15:19

Different clocks control different parts of the microcontroller. One of those clocks control the main code, while the other controls timers. By using low power modes, you turn off the main code clock but leave the other on so your timer or adc or other peripheral that runs on that timer still works. Essentially all microcontroller work this way.

What is the difference between processor clock and system clock?

3 Answers3