GPIO signal noise of Orbitty carrier board(Jetson TX2)


I am trying to control two Photocouplers(TLP785) using GPIOs output on the Orbitty board and Jetson TX2.
However, a noise (high frequency ON(3.3V)/OFF(0V) signal) occurred to a signal of some GPIOs, when I turned off GPIO.

I checked the electric current in a circuit. It was 1-3mA(3.3V) at GPIO ON.
The recommended electric current(If) of TLP785 is 16mA.

DataSheet :

I removed the resistor (10 ohm to 0 ohm) of my circuit, but the GPIO noise occurred.
I added a resistor (10 ohm to 20 ohm) to my circuit to suppress the electric current, the noise did not occur.

I think that it may become the GPIO error, when output electric currents of GPIOs increase.
Do you know the specifications of GPIO of the Orbitty board?

Hi, could you please share more information such as which GPIOs you are using to Photocouplers? What’s this 10 ohm resistor? Basically the GPIOs on Jetson board should have no errors for general usage.

Hi, Trumany-san.

GPIO which I use is as follows.

GPIO388 (Orbitty Board Pin #7) - Photocoupler#1 (green LED control)
GPIO486 (Orbitty Board Pin #10) - Photocoupler#2 (red LED control)

10 ohm is a protection resistor of the photocoupler.
To make electric current(If) of the photocoupler 16mA, I used 200 ohm. (3.3V / 16mA = 206 ohm)
However, the electric current which was enough for photocoupler ON did not flow then.
So, I chose 10 ohm among some resistors.


I think you can take a look at these related topics: