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System tick timer in stop mode

Question asked by koichimatsuo Employee on Oct 6, 2015
Latest reply on Oct 29, 2015 by koichimatsuo

Our customer, SONY has one question about System tick timer in stop mode.

They want to understand if they can use SysTick timer to wake up from STOP/PSTOP2 in K22.

 

The sentence “The System Tick Timer's clock source is always the core clock” is written in 3.2.1.2 System Tick Timer of  K22P121M120SF7RM.pdf.

So they believed that SysTick did not function in stop/Pstop2.

 

But they found one comment of Freescale AE team in last comment of http://community.arm.com/thread/7830 and then they are confusing now.

 

Extracted Freescale AE team comment from community

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It’s not very clear in the manual, but the systick is actually clocked by the platform clock which is the same frequency as the core clock. We don’t really document the difference between the two very well. Since they are the same frequency most of the time it doesn’t matter, but for low power modes it starts to become important. The platform clock runs in WAIT mode, so it is expected operation for the systick to run in WAIT mode and be able to wake you up. I think the platform clock still be available in STOP mode too, not the BUS clock and this clock's never mentioned in the RM yet.

 

 

Again, I checked Table 7-2. Module operation in low power modes of K22P121M120SF7RM.pdf

As the result, I verified that "platform clock" is off in stop mode.

 

Does anyone comment us?

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