Pi Power Status LED As a Cayenne Dashboard Input

picaxe1 · November 25, 2020, 7:32pm

We have built a nice ultra low battery powered Solar Powerd Pi0w platform. It is DC powered up by uAmp idling micro runs for 10 minutes every hour. It would be nice to know if the state of the Low Voltage / LED / Warning has been triggered as part of the monitor and control feature

Does anyone know of a handy script or process to pick this low volts / brown out state. It would be hand if it could be monitored in python or by other method forwarded to the a Cayenne dashboard.

~ A

shramik_salgaonkar · November 25, 2020, 7:45pm

Not sure if you can do this, rather check the google, you might find something related.
Also, you can continue all your doubt under one topic for cayenne related issue of your project

adam · November 29, 2020, 1:29am

It looks like you can monitor GPIO 35.

https://www.raspberrypi.org/forums/viewtopic.php?p=582098&sid=acf25316ac46eb2f6ac40a42cf23a053#p582098

github.com

MrBlinky/Raspberry-Pi-Power-LED/blob/master/pwrled.py

## Raspberry Pi B+ power LED v0.1 by Mr.Blinky ##

## General Info ##

#On the rasperry Pi B+ the power LED is controlled by an APX803 circuit.
#This circuit is a precision voltage monitor that gets activated when the
#Pi's power supply voltage drops below a certain level. When this happens
#the circuits output will be pulled low and the P's power LED turns off.
#But in the normal case when the input power is ok, the circuit is not 
#activated and the power LED is on.
#To give the Raspberry Pi the ability to detect a low voltage, the circuits
#output is also connected to a GPIO pin that can be read. This GPIO pin can
#also be configured as an output and by setting it to low we can simulate a
#low voltage and turn off the power LED.

#to turn the LED off the GPIO pin is configured as output and set to low.
#to turn the LED back on the GPIO pin is configured as input again.

#This can be safely done as the the circuits output is an opendrain output
#which acts like a switch. When not active it is open and the GPIO pin is

This file has been truncated. show original

picaxe1 · November 29, 2020, 5:40am

Thanks for these ideas.

I think rather than follow the status of the LED the better way would be to dev some script and find the bit within the vcgencmd get_throttled command.
vcgencmd get_throttled
This returns a hex number in which the following bits may be set:
0: under-voltage
1: arm frequency capped
2: currently throttled
16: under-voltage has occurred
17: arm frequency capped has occurred
18: throttling has occurred
https://www.raspberrypi.org/forums/viewtopic.php?p=1380859

This could be handy for monitoring the other states and tracking issues and bugs in stressed hardware. Will update if I get something like a script together that posts to a custom dashboard widget

~ A

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Pi Power Status LED As a Cayenne Dashboard Input

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