Hardware shutdown switch for RPi

Sometimes I need to power off one of my Raspberry Pis, and since I run these computers headless, going to a remote SSH terminal to issue a shutdown command can be extra work. I saw a webpage mentioning using a simple 2 pin jumper to initiate a shutdown script for the Pi. So that’s what I did (green tab on the GPIO pins), I chose python due to the wait_for_edge function.

This script will shutdown the RPi when the tab is pulled. Strangely the RPi will boot if you plug the jumper back in after it has shutdown, or if you pull it out after it has completed shut down (putting it back before it has completed shutting down). If there is no jumper in during boot, then the script will close.

#!/usr/bin/env python
#note crontab for superuser required a new PATH variable as here http://unix.stackexchange.com/questions/43392#answer-43394
import subprocess
 import RPi.GPIO as GPIO
except RuntimeError:
 print("Error importing RPi.GPIO! This is probably because you need superuser privileges. You can achieve this by using 'sudo' to run your script")

GPIO.setup(5, GPIO.IN) #Hardware Pullup on this pin..

ShutdownCommand = ['shutdown', '-h', 'now', '"System halted by GPIO action"']

if GPIO.input(5) == 0:
 #run script waiting for jumper removal
 GPIO.wait_for_edge(5, GPIO.RISING)
 KillProcess = subprocess.Popen(ShutdownCommand, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
 MountData, MountError = KillProcess.communicate()

Then I simply added this script to the bottom of my root crontab (sudo crontab -e) to run at reboot:

@reboot python /usr/local/sbin/ShutdownJumper.py

Monitoring RPi Temp and CPU with Thingspeak

I made the following python script to update CPU Temperature and 5 minute average CPU load of my RPi to Thingspeak:

#!/usr/bin/env python
import subprocess
import httplib, urllib

GetTempCommand = "cat /sys/class/thermal/thermal_zone0/temp"
GetCPUCommand = "cat /proc/loadavg"

GetTempProcess = subprocess.Popen(GetTempCommand.split(), stdout=subprocess.PIPE)
GetTempOutput = GetTempProcess.communicate()[0]
Temp = float(GetTempOutput) / 1000
#print Temp
GetCPUProcess = subprocess.Popen(GetCPUCommand.split(), stdout=subprocess.PIPE)
GetCPUOutput = GetCPUProcess.communicate()[0]
CPU = GetCPUOutput.split()
#print CPU[1]

params = urllib.urlencode({'field1': CPU[1],'field2': Temp, 'key':'######'})     # use your API key generated in the thingspeak channels for the value of 'key'
# temp is the data you will be sending to the thingspeak channel for plotting the graph. You can add more than one channel and plot more graphs
headers = {"Content-typZZe": "application/x-www-form-urlencoded","Accept": "text/plain"}
conn = httplib.HTTPConnection("api.thingspeak.com:80")                
    conn.request("POST", "/update", params, headers)
    response = conn.getresponse()
    data = response.read()
    print "connection failed"

The script is run every 5 mins using cron ($ crontab -e):

*/5 * * * * python "/home/ubuntu/logging/TempCPUtoThingspeak.py"

I borrowed some script from here and here.

LinkyMcLinkFace Part 2

So my initially Nanobridge factory reset itself, before resetting itself every minute or so. I assumed it was due to my crappy wiring initially. First thing I did was get a Ubiquiti ETH-SP Ethernet Surge Protector, this really is more related to the safety of the LAN than anything else, except that now I have the Ethernet port for the NanoBridge accessible from my ceiling. When I went to install the ETH-SP I found one pair of the network cable wasn’t connected properly.

Continue reading “LinkyMcLinkFace Part 2”