Clock configuration and SYSCLK for STM411RE

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SpotlightKid
Posts: 463
Joined: Wed Apr 08, 2015 5:19 am

Clock configuration and SYSCLK for STM411RE

Post by SpotlightKid » Sat Mar 05, 2016 11:19 pm

I see that the configuration for the pyboard lite and the STM32F411DISC set the STM411(RE) to run at 84 Mhz even though it can run with up to 100 Mhz. Is there a particular reason for this?


Update: Oops, sorry, it's 96 Mhz for the pyboard lite. But 100 Mhz should still be possible, shouldn't it?

chrismas9
Posts: 152
Joined: Wed Jun 25, 2014 10:07 am

Re: Clock configuration and SYSCLK for STM411RE

Post by chrismas9 » Sun Mar 06, 2016 12:19 am

I believe you can't derive the 48MHz USB clock when you set the PLL to 100 MHz

SpotlightKid
Posts: 463
Joined: Wed Apr 08, 2015 5:19 am

Re: Clock configuration and SYSCLK for STM411RE

Post by SpotlightKid » Sun Mar 06, 2016 4:37 am

Yes, I figured this out myself after I had written the post. The closest you can get is 50 Mhz for the peripheral clock - or you overclock the cpu at 108 Mhz :)

Still leaves the question why the STM32F411DISC is configured at 86 Mhz instead of 96 Mhz?

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