STM32H7 maximum timer frequency

[Uwe Bonnes]

Posted on June 26, 2017 at 17:14

Hello,

the STM32H743 datasheet is out. I think the datasheet disaggrees on 'Max timer clock'. Table 4 in footnote 1 tells that 400 MHz is possible depending on  the TIMPRE bit, while electrical characteristics 6.3.31 Timer characteristics has a maximum clock value of 200 MHz.

#stm32h7

[Tilen MAJERLE]

Posted on June 27, 2017 at 09:38

Hello Uwe,

maximal clock for timer TIM1-TIM17 is 200MHz, while Systick timer can work up to 400MHz.

In the table for timer specifications Table 98: Timer specifications, you have this note:

The maximum timer frequency on APB1 or APB2 is up to 200 MHz, by setting the TIMPRE bit in the RCC_CFGR register, if APBx prescaler is 1 or 2 or 4, then TIMxCLK = rcc_hclk1, otherwise TIMxCLK = 4x Frcc_pclkx_d2

You can find details about setting bit for prescalers in RCC registers in reference manual RM0433 on Table 48: Ratio between clock timer and pclk.

When you come to situation where you are not sure about maximal clock setup, you can always use STM32CubeMX and select MCU you are interested in. Later, you can play with Clock Configuration window to check available values.

[Uwe Bonnes]

Posted on June 27, 2017 at 10:24

Please comment on footnote (1) in Table 4 stm32h743(XX).pdf

[Tilen MAJERLE]

Posted on June 27, 2017 at 11:23

Hello

Bonnes.Uwe

‌,

Table looks ok and footnote too. Maximal clock isup to 400MHz and it is only for HRTIM which is high resolution timer. It has interface and tick clock up to 400MHz, while all others have interface clock up to 100MHz and tick clock up to 200MHz.