frequencies of STM32F4

[betuel]

Posted on October 17, 2012 at 11:48

Hi everyone!

I'm new to the world of microcontrollers,

these days I'm

doing my

first

espeienze

with

STM324

discovery,

I'm reading

the various manuals

and trying out the

various

examples, but

I can not understand

how you set the

various frequencies

HSE

, HSI

and

especially

APB1e

AP2

could you give me

directions?

thanks

[Tesla DeLorean]

Posted on October 17, 2012 at 13:46

You might want to review the clock tree in the manual.

HSI is fixed by the internal oscillator

HSE is fixed by the external crystal

APB1, and ABP2 are set to fractional (/1, /2, etc) of the AHB clock

The PLL clock can get you any clock up to 168 MHz (VCO actually is twice that), which you can factor from the PLL settings with a 1-2MHz comparison frequency.

You will typically set these parameters in system_stm32f4xx.c, and by the C initialization call SystemInit()

[betuel]

Posted on October 18, 2012 at 13:44

thank you very much

!

between all the manuals I have a bit of confusion ...do you want tell me in which manual is the clock tree?

 

[Tesla DeLorean]

Posted on October 18, 2012 at 14:10

The Reference Manual, Figure 9, Page 85

http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/REFERENCE_MANUAL/DM00031020.pdf