STM32H7 series resistors in data lines ?

[MikeDB]

With a 400MHz clock and very high speed ports, I was assuming the faster data lines would need series resistors to avoid reflections in the way things like FPGAs do. But I've just noticed the evaluation board doesn't have any and routes even high speed lines off the board and to the LCD without any. The DSA lines are even labelled at 500MHz clocking.

Do STM MCUs have some way to avoid signal reflection (internal resistors ?) or should I leave them in anyway. It would save quite a bit of board space to remove them as I've got quite a lot of buses going between multiple MCUs.

[Tesla DeLorean]

One can reduce the slew-rate/drive on the pins. There are references to a "compensation cell"

But yes, I'd probably look to have the option to put series resistors on shorter runs. Frequently recommended for eMMC devices, for instance.

[MikeDB]

Ah I'd noticed the compensation cell mentioned as being enabled in the data sheet current consumption figures but that's the only time it's mentioned, at least in the H750 datasheet.

How to enable it and what it does isn't explained. I'll dig deeper in STM's other documents. Thanks very much for the lead as it sounds to be what I need.

...........

And indeed it was. Document RM0433 section 11.3.7 for anyone else designing their own PCBs who hasn't noticed this feature.