LED added to the Dashboard but immediately shown as Unreachable


Using a Pi 3 Model B with the Web dashboard. Following the example in the New User documentation, I added a LED and attached it to Pin 23. The LED seemed to be successfully added but when I went to the Dashboard, in a few second Chayenne displayed the word “Unreachable”. I removed the LED and recreated it attached to pin 5 but it too was marked as Unreachable. I then measured the voltage on Pin 23 with a meter and the Pin seems to stay as .2 V rather than the expected value of 3.3 V. In an attempt to pin down the problem, I move the jumper from Pin 23 to 3.3 V on the T Cobbler and the LED turned on successfully so it seems to me that Chayenne is not successfully reaching the GPIO pin on the Pi. Any suggestion will be gratefully accepted -) Jerry Hoffman


Are you using the Cayenne agent, or MQTT to switch the LED on/off?


I don’t what you mean by “MQTT” but I am simply following an example in the user documentation. I wired up this circuit:

I then went through the “Add New > Device / Widget” function and defined the new widget as a light actuator light switch on channel 23. When I pressed
the “Add Actuator” button, the Dashboard was re-displayed and within a couple of seconds the widget was marked Unreachable.

           Jerry Hoffman


HI @wolfman5,

Do you know what version of Raspbian you are using?



I was told by multiple users that this is the last version of Jessie that was available:

https://www.element14.com/community/external-link.jspa?url=https%3A%2F%2Fdownloads.raspberrypi.org%2Fraspbian%2Fimages%2Fraspbian-2017-07-05%2F2017-07-05-raspbian-jessie.zip https://downloads.raspberrypi.org/raspbian/images/raspbian-2017-07-05/2017-07-05-raspbian-jessie.zip





I think you might be running into the 4.9 kernel issue. Can you run the following command and post back the result?

uname -a


Here it is:

Uname -a

Linux raspberrypi 4.9.35-v7+ #1014 SMP Fri June 30 14:47:43 BST 2017 armv71 GNU/Linux


Yeah, looks like the 4.9 kernel issue again. See this post here for an explanation and a command to run that will take you back to the 4.4 kernel.


After restoring the 4.4 Kernel, I repeated my steps to attach a LED to the Pi and it worked perfectly.


           Jerry Hoffman



I just wanted to bump this thread to note that we’ve now updated our Pi agent to support the 4.9 kernel (it still supports 4.4 as well). The update was automatic in the background so there is nothing you need to do on your end. Feel free to use rpi-update to move forward to the 4.9 kernel at this point if you’d like!