About VolkerKugler

VolkerKugler · 2020-09-02

We want to realise a cheap measurement of a external voltage over a voltage divider with a STM32F765ZI processor. We calculate VIL with the formula "0,35*VDD-0,04" which is guaranteed by design. On base of this calulated VIL we calculate our voltage ...

VolkerKugler · 2020-09-02

In the datasheet of the STM32F765ZI and many other datasheets I have read, the specification value of hysteresis voltage between Schmitt trigger switching levels is missing. There is a comment (8) under the table (here table 66 I/O static charasterit...

VolkerKugler · 2020-09-03

Can I believe on the levels for VIL and VIH given in the datasheet with "guaranteed by design", when the hysteresis (guaranteed by design) is not exactly like defined in the datasheet?

VolkerKugler · 2020-09-03

I tried more measures directly at the CPU pins without a voltage divider and on more pins. What I can see is, that the hysteresis on most of the pins is only 30mV to 70mV and they toggle extremly. Less of the pins have a hysteresis of about 200 to 27...

VolkerKugler · 2020-09-03

I tried to measure directly at the pins PF0 to PF7 of a nucleo STM32F767ZI to get a better idea of the real situation.What I can see is, that PF0 to PF5 toggle extremly when starting at 0V and turn up the voltage slowly. They start toggeling at 1,50V...

VolkerKugler · 2020-09-03

No, that are voltages at a resistor voltage divider with the factor 0,4351.That means 3,115V at the divider = 1,3553V at the pin of the controller.

VolkerKugler · 2020-09-03

Thanks, and this has no tolerance? We have measured the hysteresis on two pins.One pin has 340 mV, that was nearly the specified value of 331mV (10% VDD), but the other pin has only a hysteresis of about 96 mV.Best regardsVolker

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Exact meaning of VIL and VIH and the resulting switching point between HIGH and LOW

Missing "hysteresis voltage between Schmitt trigger switching levels" in datasheet

Re: Missing "hysteresis voltage between Schmitt trigger switching levels" in datasheet

Re: Exact meaning of VIL and VIH and the resulting switching point between HIGH and LOW

Re: Missing "hysteresis voltage between Schmitt trigger switching levels" in datasheet

Re: Exact meaning of VIL and VIH and the resulting switching point between HIGH and LOW

Re: Missing "hysteresis voltage between Schmitt trigger switching levels" in datasheet