Jetson Nano Dev Kit SPI MISO shifted up by 1.2v

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We are running into an issue with SPI MISO line on the Jetson nano devkit where the input doesn’t get pulled low all the way to 0v but rather stays around ~1.24 volts.

Here is an output from our motor driver chip, without plugging it into the Jetson Nanos MISO input. It toggles from 0 to around 2.292 V (it should be 3.3 but that seems to be another unrelated issue with our tristate buffer circuit)

This is the logic analyzer trace after the MISO is plugged into the Jetson MISO. The logic high stays around 2.29v but the logic low is shifted up to 1.236v.

The reason why we are investigating this in the first place is that the MISO line has been very unreliable, and we’ve been getting noisy data.

Any advice on where this 1.2v may be coming from? Thanks in advance!

Hi, please check below 40-pin header docs first. There are some requests on the usage of these pins.

https://developer.nvidia.com/jetson-nano-developer-kit-40-pin-expansion-header-gpio-usage-considerations-applications-note

https://developer.nvidia.com/embedded/dlc/Jetson-Nano-40-Pin-Expansion-Header-1.1

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