APB 1 36MHz Limit

[sirpak]

Posted on October 01, 2013 at 21:43

I am using STM32F103R6 for a motor control application.

STM states that the APB 1 frequency limit is 36 MHz, but I am using it with 72MHz and it looks like that all peripherals work fine. What risk am I taking? Is there a particular peripheral that need this limit?Has already someone experienced something like this?Thanks in advance,Marco #core-peripheral-clock #clock-config

[Tesla DeLorean]

Posted on October 01, 2013 at 21:58

Why?

The timers can run at 72 MHz if the APB is at 36 MHz, what are you running that needs to be at 72 MHz? It's not going to catch on fire, the likely result is that data will be clock incorrectly over temperature.

[sirpak]

Posted on October 10, 2013 at 10:24

Thanks for the quick reply.

How can I run the timers at 72MHz while clocking them with a bus at 36MHz?As far as I know the prescaler can only divide the input frequency.Thanks,

[sirpak]

Posted on October 10, 2013 at 10:25

How can I run the timers at 72MHz while using a clock at 36?

[Tesla DeLorean]

Posted on October 10, 2013 at 13:57

How can I run the timers at 72MHz while using a clock at 36?

If you run the APB1 at 36 MHz, then the TIMCLK will still be at 72 MHz, please review the Clock Tree.