I’m trying to wire up a button to the AGX xavier developer kit carrier board, using the following switch. I would like the button to be used to power on the Xavier, and would like one of the LEDs (e.g. green) to light up when the Xavier is on, similar to a front panel button on many computer cases.
I’ve been able to use the automation header on the developer kit carrier board to power on the xavier (shorting pins 1 (GND) and 4 (BUTTON_POWER_ON) with the momentary button). I then tried wiring pins 1 (GND) and 5 (CCG4_LED) into the one of the LEDs on the switch, but the LED is on the entire time, even when the Xavier isn’t booted (but power is applied via the barrel jack).
Is there a way to change the behavior of this (CCG4_LED) pin so that it is only high when the Xavier is booted, rather than all the time? Alternatively, is there another pin I should be using to achieve this?
You can use one of the GPIO pins on the 40-pin “raspberry pi” header.
You may want to use a current limiting resistor, probably around 1 kOhm, to make sure you don’t pull too much current from the pin.
Then use a script/system that runs early in the start process that turns on the GPIO pin.
The drawback of this mode is that the Jetson will actually be “on” for a little while before it gets to your GPIO script.
Another option would be to look at the 3V3 output rail that’s on the GPIO header, and see if that is off while power is not on, and turns on when you power on the Jetson. That seems like it might happen. If so, again, use a current limiting resistor, and power the LED from that pin.
Thanks snarky. I just tested and both the 3v3 and 5v GPIO lines work on the 40 pin header for this purpose (that is, they’re not pulled high until the system boots). The switch has an internal resistor, so a separate external one isn’t needed. I was hoping that there was a way to configure the CCG4_LED pin to do the same because it makes the wiring a little neater, but this is a good fallback option.