Continuing the discussion from GPIO current limits on Jetson Nano:
Hi,
I’m trying to use the GPIO pins on the Jetson Nano Developer board. When I try to turn Board Pin 12 to HIGH, the output voltage becomes 1.8 V instead of 3.3 V. Multiple articles say that the in-built level shifter keeps it at 3.3 V by default, and that we can ‘reconfigure’ the pins to make that 1.8 V instead, but I cannot seem to figure out why I am getting 1.8 instead of 3.3 V . Please help ! I would like to get 3.3 V.
Do you mean the pin 12 of J41 connector? You can refer to the carrier board schematic (P3449) in DLC for the connection of level shift and connector. It should be 3.3V since it passes through a 1.8V to 3.3V level shift. If it is not 3.3V, maybe something wrong during your test and also you can check the 40-pin header doc in DLC for the requests of load of the pins.
Yes, Pin 12 of the J41 40-pin GPIO. Nothing is wrong during the test. When I connect an LED across this pin and GND, it lights up very dimly. When I check the voltage using a multimeter or a low capacitance mode oscilloscope, it shows 1.8 V. When I set the pin to LOW, it shows 1.4 V. So the pin is obviously outputting 1.8 instead of 3.3 V. I know that’s a problem, and that’s the whole reason why I asked for specific help on this forum. The DLC link that you repeatedly share shows me 233 files, so could you please show me exactly which file I need to look at? I have gone through almost every file on the board but have been unable to locate any help on this matter.
Additionally, I saw that multiple other users had the same problem and posted about it here. Your replies to them said the same vague thing that it should be 3.3 V and asked them to check “documentation” on how to toggle between 1.8 and 3.3 V, but you never actually mention how we can change that.
If you know how to solve this problem, please help me out. Otherwise, please point me to someone else who can fix it.
Have you searched “P3449” and “40-pin” in DLC as I comment? Here are the links: https://developer.nvidia.com/jetson-nano-carrier-board-design-files , https://developer.nvidia.com/jetson-nano-developer-kit-40-pin-expansion-header-gpio-usage-considerations-applications-note
Dear Trumany,
I just read through both these documents. I still don’t understand what problem is causing my GPIO pins to fluctuate between 1.8V high and1.2 V low, and how I can fix this specific issue. I have read the documents and checked all connections. I am still having the problem. Can you please tell me what the problem is, and what I should do to fix it?
The GPIO 5V and 3.3V supply pins are outputting the accurate voltage FYI. Only the GPIO pins are outputting lower values when I set them to logic HIGH or LOW.
Please tell me exactly how to fix this issue and get the accurate 3.3V HIGH on GPIO pins.
First, you can check and make sure your measurement load is in the requested range in doc that will guarantee the voltage level won’t be affected by measuring. And you can check the pin level of 1.8V side of level shift to check if the output 1.8V from module is correct. If no problem with your measurement, you can also check other pins from same level shift and other level shift to make sure it is a pin related issue or level shift issue. If you can confirm it is module or level shift issue, you can run RMA for the devkit then.
Thank you so much! Please tell me how I can access the 1.8V side of the level shifter. I don’t see it on the board. Do I have to unscrew and remove the module from the Dev board in order to access it?
The level shift is on carrier board not on module. You can get the level shift (U48) location by the schematic and assembly file of carrier board (P3449) in the doc package in DLC. Log in | NVIDIA Developer
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