1,5V in GPIOs. Is this normal? (AGX XAVIER)

Hi guys, I’m using the GPIOs to work with a MOSFET, and I noticed that the mosfet was not saturating, so I checked (with a multimeter) the voltage of the GPIO I was using (pin 18), and the voltage was 1,5V. I was expecting to have 3,3 V there.

So, is this normal? Is there any way to use a GPIO with 3,3V?

Thanks in advance

Hi, what is the connector of this pin 18? Have you measured the voltage level by disconnecting MOSFET? You can find voltage level of each pin in TX2 pinmux sheet in DLC.

This is the GPIO diagram

Yes, I have measured the voltage without any load, just using the multimeter on the naked pins.

Why am I getting 1,5V instead of 3,3V ?

What about other pins of the connector, like pin 15? It should be 3.3V too. Pin 18 and Pin 15 are routed through a 1.8V to 3.3V level shift, so in normal situation it should be 3.3V. And you can check the J514 jumper, it is to select output voltage (1.8V/3.3V) of level shift.

I’ve placed that jumper to use 3.3V and now I have 3.3V on that GPIO, but when I connect a transistor to the GPIO, the voltage drop to 1.5V.
I’m not moving big loads, just a transistor, so I don’t know why the voltage is dropping so much.
Is there any solution to this?
Thanks in advance

You can check the level shift info in the doc (https://developer.nvidia.com/jetson-nano-developer-kit-40-pin-expansion-header-gpio-usage-considerations-applications-note), there are some requests for the usage of load.

Hi @Trumany,
In my case, I’m not using jetson nano, but AGX Xavier.
Is there any solution to have a bigger current on the gpios in this board?

It is same level shift on Xavier board. Please refer to that doc.

I’ll add a note that if that is a bipolar transistor, then it draws a bit of current which you wouldn’t see with an FET or MOSFET. Most of the time, unless you have a low current draw device, you’ll end up buffering with a logic gate before using the output. Often GPIO is used directly with some sort of logic board (with FET/MOSFET tech), and so it never needs the buffering. Also, the reason for assuming TX2 is that this was posted in the TX2 forum (although the title did say Xavier, but there is an Xavier AGX forum).

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