Lolin D32 PRO Reverse Voltage on I2C port!!!

[perigalacticon]

I just tested the I2C port for the first time on my Lolin D32 PRO board and found that it supplies NEGATIVE VOLTAGE to the I2C port!!! I used a standard I2C cable from Adafruit and when I connected it to my Adafruit Seesaw board it got very hot and didnt power up so I then connected the cable to a breadboard I2C port adapter and using a voltmeter found that the supply voltage is actually 3.3V!!! I tried to find a contact for Lolin/Wemos but couldn't really find anything so if you know how to please let me or them know.

[Sprite]

That would be very surprising, as that board does not to have any components that are capable of inverting the input voltage. How did you measure this?

[perigalacticon]

The schematic for the board shows the port pinoit is different from the standard stemma I2C port. I am so effing annoyed at the lack of standardization among hardware and code for arduino.

[perigalacticon]

Pinout. Why cant you edit your own posts on this forum?

[lbernstone]

There's no native pins for I2C. You can assign whatever pins you want to a Wire object bus. The author of arduino-esp32 has provided some suggested pins in the variant file. The bus needs pull-up resistors on the pins (maybe more than what the internal iomux can supply), so if you measure the voltage on an active bus, it will be high during idle periods.

[perigalacticon]

You dont know what your talking about. I am talking about the I2C port on the board, its a 4-pin JST SH 1.0 connector. Typically known as Stemma QT or Qwiic by adafruit and sparkfun respectively.

[MicroController]

found that the supply voltage is actually 3.3V!!!

Of course it is. Why wouldn't it?

You dont know what your talking about.

But now you have learned a lesson: Never just assume that different vendors use the same pinout for their proprietary connections; always check the documentation before plugging things together.

[perigalacticon]

Yeah it was missing a minus sign. something I could have changed if you could edit your own posts. What I learned is that Lolin and Arduino sucks.

[MicroController]

On PC, I can edit my posts ("pen" button at the top-right of the post). The mobile version of the forum seems a little broken.