Functionality of test points in Beagleboard black

General Discussion
1

On the documentation, there is a very short list outlining the function of the test points, TP5 thru TP8. The schematics do not show anything else.

Let me tell you what I actually require: I am sending a remote signal for the board to power down, and I need to know when the power down has actually occurred for me to release the remote signal.

The manual mentions: If you push and hold the button for greater than 8 seconds, the PMIC will power down. But you must release the button when the power LED turns off. Holding the button past that point will cause the board to power cycle.

I am attempting to emulate that functionality from a remote location. Is TP4 the correct point to verify that the LED, and thus the unit, has turned off?

2

There is an alternative approach which may or may not work for you, but it might be easier and less fragile. It doesnt require simulating a button press or monitoring a test point and doesnt need timing loops.

You can shut the system down with the reboot(RB_POWER_OFF) c function. There would probably be a python equivalent. It needs the #include <sys/reboot.h> include.

To use it, add code to the bbb to monitor a gpio then call the reboot() function as required. Your remote device then pulls the gpio to power down the board. If you already have communication between the remote device and the bbb, you may not even need the gpio.

Paul

3

I can’t help thinking this sounds like something that has already been done before…

How about telling nut what pin to look for and let it handle the rest?

4

Thanks, bbb;

Let me try this solution, and report back.

5

#include <sys/reboot.h>…nice.

I was also unaware of this facet.