Posted on May 23, 2018 at 11:32
Hello, I�m struggling understanding the I/O static characteristics for the STM32H7 devices.
I think that below 0.3xVdd a normal input is low and above 0.7xVdd it is high. But what is the meaning of the red marked lines?
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#stm32h7 #vil #vih
Posted on May 29, 2018 at 16:47 
So, if you're using a voltage values above ''0.3*VDD'' but below ''0.4*VDD - 0.1'', the state of the pin is considered as low. The same for the high state, if the voltage is above ''0.47*VDD + 0.25'', the state is high even if the voltage is below ''0.77*VDD''. The two values are kept in order to show that using the STM32, we minimize the voltage interval in which the state of the pin is undetermined. 
Hi
Noetzold.Kilian
,After further check, we found that the information shown on the datasheet are correct and will not be removed.
Actually, the first lines (colored in green) show the standard voltage values below/above them the input voltage is considered as low/high (general rule).
On the second lines (colored in red), we precise the voltage characteristics particularto the STM32H7 pins. So, if you're using a voltage values above ''0.3*VDD'' but below ''0.4*VDD - 0.1'', the state of the pin is considered as low. The same for the high state, if the voltage is above ''0.47*VDD + 0.25'', the state is high even if the voltage is below ''0.77*VDD''. The two values are kept in order to show that using the STM32, we minimize the voltage interval in which the state of the pin is undetermined. Hope this is clear and sorry for my first answer.
Khouloud.
Posted on June 01, 2018 at 10:12
Hi
Khouloud,
thank you for explaining!
Now I understood the purpose to but it is a bit confusing that the same Parameters have different Max/Min values and it is not clear that red overrules green. Maybe a footnote would be helpful.
Never the less at least the blue marked ''low'' should be ''high''.
Kilian
