The rpisystat script will report the following system parameters to your LCD:

  • Internal IP
  • External IP
  • CPU temperature
  • GPU temperature
  • CPU usage
  • Memory usage
  • Free disk space
  • Incoming and outgoing network traffic

You need:

1. Breadboard with T-Cobbler (or connect the wires directly)
2. 16×2 LCD board
3. Adjustable resistor (potentiometer) for adjusting LCD contrast

1. Wiring (source:×2-lcd-directly-with-a-raspberry-pi/wiring):

Pin #1 of the LCD goes to ground (black wire)
Pin #2 of the LCD goes to +5V (red wire)
Pin #3 (Vo) connects to the middle of the potentiometer (orange wire)
Pin #4 (RS) connects to the Cobbler #25 (yellow wire)
Pin #5 (RW) goes to ground (black wire)
Pin #6 (EN) connects to Cobbler #24 (green wire)
Skip LCD Pins #7, #8, #9 and #10
Pin #11 (D4) connects to cobbler #23 (blue wire)
Pin #12 (D5) connects to Cobbler #17 (violet wire)
Pin #13 (D6) connects to Cobber #21 (gray wire)
Pin #14 (D7) connects to Cobber #22 (white wire)
Pin #15 (LED +) goes to +5V (red wire)
Pin #16 (LED -) goes to ground (black wire)


This schematics is for RaspberryPi 1 version, but you can connect to the same pins on RaspberryPi 2 (picture bellow).


2. Software

Download required packages:

sudo apt-get update
sudo apt-get install python-dev python-setuptools python-pip git
sudo easy_install -U distribute
sudo pip install rpi.gpio

Download my scripts:

sudo git clone git://
cd 16-2-LCD-rpisystat
sudo ./

Make sure you edit to match your GPIO pins (default is for the wiring above). Also edit and to match your network adapter.

Check the display in action:



In my previous post, I was writting about how to graph temperature and humidity from AM2302 sensor on RasberryPi. In addition, we will add dewpoint monitoring. We need two variables to calculate dewpoint, temperature and humidity. I took some already made scripts and combined them together to fit my needs. I wanted to calculate dewpoint completely with bash and bc, but since I’m to lazy, I just used the python script from this blog.

Get to the root shell (we don’t want to type sudo everytime):

sudo -s

Create python script (for dewpoint calculations):

pico /opt/

Paste the code, save and exit (CTRL + C), Y, ENTER

import sys
import numpy as np

# approximation valid for
# 0 degC < T < 60 degC
# 1% < RH < 100%
# 0 degC < Td < 50 degC

# constants
a = 17.271
b = 237.7 # degC

# sys.argv[0] is program name

def dewpoint_approximation(T,RH):

    Td = (b * gamma(T,RH)) / (a - gamma(T,RH))

    return Td

def gamma(T,RH):

    g = (a * T / (b + T)) + np.log(RH/100.0)

    return g

Td = dewpoint_approximation(T,RH)
print Td

Make the script executable:

chmod +x /opt/

Create plugin file:

pico /etc/munin/plugins/dewpoint

Paste the code, save and exit (CTRL + C), Y, ENTER


case $1 in
cat <<'EOM'
graph_title Dewpoint
graph_vlabel Celsius
graph_category AM2302
dewpoint.label Temperature
dewpoint.draw AREASTACK
dewpoint.colour 403075
exit 0;;

humidity=$(/opt/lol_dht22/loldht 7 | grep -i "humidity" | cut -d ' ' -f3)
temperature=$(/opt/lol_dht22/loldht 7 | grep -i "temperature" | cut -d ' ' -f7)

printf "dewpoint.value "
python /opt/ $temperature $humidity
chmod +x /etc/munin/plugins/dewpoint

Open munin-node file:

pico /etc/munin/plugin-conf.d/munin-node

Add the line at the end of the file, save and exit:


Restart services:

/etc/init.d/munin-node restart



  • RasberryPi 2
  • AM2302 humidity/temperature sensor
  • Some wires from old PCs to connect sensor with RaspberryPi


  • Raspbian OS
  • Nginx
  • Munin
  • WiringPi
  • Lol_dht22

1. Solder wires to the sensor like on the picture above, and connect them to the correct pins:

Pin 1 on the AM2302 to pin 1 (+3.3V) on the GPIO connector (labeled P1 on the raspi)
Pin 2 on the AM2302 to pin 7 (GPIO 4) on the GPIO connector
Pin 4 on the AM2302 to pin 9 (Ground) on the GPIO connector

For detailed instructions, check this blog up to step 4:

All shell commands will be run as root, so I will not use sudo.

2. Install Nginx (web server)

apt-get update
apt-get install nginx php5-fpm

3. Install Munin

Muning is a monitoring tool for sysadmins. It creates graphs to monitor various parameters. We will configure munin to display AM2302 sensor in graphs.

apt-get install munin munin-node munin-plugins-extra

Edit munin configuration file:

pico /etc/munin/munin.conf
 use_node_name yes

4. Configure Nginx virtual host. Dynazoom will work with this config.

pico /etc/nginx/sites-enabled/default or pico /etc/nginx/sites-enabled/
server {
        listen 443 ssl;
        ssl_certificate /etc/nginx/ssl/;
        ssl_certificate_key /etc/nginx/ssl/;
        root "/var/cache/munin/www/";
        auth_basic            "Private access";
        auth_basic_user_file  /etc/munin/munin_htpasswd;

        location ^~ /munin-cgi/munin-cgi-graph/ {
                fastcgi_split_path_info ^(/munin-cgi/munin-cgi-graph)(.*);
                fastcgi_param PATH_INFO $fastcgi_path_info;
                fastcgi_pass unix:/var/run/munin/spawn-fcgi-munin-graph.sock;
                include fastcgi_params;

        location /static/ {
                alias /etc/munin/static/;

5. Generate SSL cert

mkdir /etc/nginx/ssl
openssl req -subj '/' -x509 -nodes -days 365 -newkey rsa:2048 -keyout /etc/nginx/ssl/ -out /etc/nginx/ssl/

6. Generate website password

apt-get install apache2-utils
htpasswd -c /etc/munin/munin_htpasswd admin

You will be promted to enter a new password.

7. Add common modules to munin

cd /usr/share/munin/plugins
wget -O pisense_
chmod a+x pisense_
ln -s /usr/share/munin/plugins/pisense_ /etc/munin/plugins/pisense_temp
ln -s /usr/share/munin/plugins/pisense_ /etc/munin/plugins/pisense_clock
pico /etc/munin/plugin-conf.d/munin-node
user root

8. Configure AM2302 prerequisites

apt-get install git-core
cd /opt/
git clone git://
cd wiringPi
cd /opt/
git clone
cd lol_dht22

9. Create plugins for munin

pico /etc/munin/plugins/DHT22-humidity

case $1 in
 cat <<'EOM'
graph_title Relative humidity
graph_vlabel Percent
graph_category AM2302
humidity.label RH
humidity.draw AREASTACK
humidity.colour 3E9BFB
 exit 0;;

printf "humidity.value "
/opt/lol_dht22/loldht 7 | grep -i "humidity" | cut -d ' ' -f3
chmod +x /etc/munin/plugins/DHT22-humidity
pico /etc/munin/plugins/DHT22-temperature

case $1 in
 cat <<'EOM'
graph_title Temperature
graph_vlabel Celsius
graph_category AM2302
temperature.label Celsius
temperature.label Temperature
temperature.draw AREASTACK
temperature.colour 00FF00
 exit 0;;

printf "temperature.value "
/opt/lol_dht22/loldht 7 | grep -i "temperature" | cut -d ' ' -f7
chmod +x /etc/munin/plugins/DHT22-temperature
pico /etc/munin/plugin-conf.d/munin-node

Add this to the end of the file:

user root

10. Enable Dynazoom for graphs

apt-get install spawn-fcgi libcgi-fast-perl
pico /etc/init.d/munin-fastcgi
#! /bin/sh

# Provides: spawn-fcgi-munin-graph
# Required-Start: $all
# Required-Stop: $all
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Description: starts FastCGI for Munin-Graph
# --------------------------------------------------------------
# Munin-CGI-Graph Spawn-FCGI Startscript by Julien Schmidt
# eMail: munin-trac at
# www:
# --------------------------------------------------------------
# Install: 
# 1. Copy this file to /etc/init.d
# 2. Edit the variables below
# 3. run "update-rc.d spawn-fcgi-munin-graph defaults"
# --------------------------------------------------------------
# Special thanks for their help to:
# Frantisek Princ
# Jérôme Warnier
# --------------------------------------------------------------
# Last Update: 14. February 2013
# Please change the following variables:

DAEMON_OPTS="-s $SOCK_FILE -F $FCGI_WORKERS -U $SOCK_USER -u $FCGI_USER -g $FCGI_GROUP -P $PID_FILE -- /usr/lib/munin/cgi/munin-cgi-graph"

# --------------------------------------------------------------
# No edits necessary beyond this line
# --------------------------------------------------------------

if [ ! -x $DAEMON ]; then
 echo "File not found or is not executable: $DAEMON!"
 exit 0

status() {
 if [ ! -r $PID_FILE ]; then
 return 1
 for FCGI_PID in `cat $PID_FILE`; do 
 if [ -z "${FCGI_PID}" ]; then
 return 1
 FCGI_RUNNING=`ps -p ${FCGI_PID} | grep ${FCGI_PID}`
 if [ -z "${FCGI_RUNNING}" ]; then
 return 1
 return 0
start() {
 if status; then
 echo "FCGI is already running!"
 exit 1

stop () { 
 if ! status; then
 echo "No PID-file at $PID_FILE found or PID not valid. Maybe not running"
 exit 1
 # Kill processes
 for PID_RUNNING in `cat $PID_FILE`; do
 kill -9 $PID_RUNNING
 # Remove PID-file
 rm -f $PID_FILE
 # Remove Sock-File
 rm -f $SOCK_FILE

case "$1" in
 echo "Starting $NAME: "
 echo "... DONE"

 echo "Stopping $NAME: "
 echo "... DONE"

 echo "Stopping $NAME: "
 echo "Starting $NAME: "
 echo "... DONE"
 if status; then
 echo "FCGI is RUNNING"
 echo "Usage: $0 {start|stop|force-reload|restart|status}"
 exit 1

exit 0
chmod 755 /etc/init.d/munin-fastcgi
update-rc.d munin-fastcgi defaults
/etc/init.d/munin-fastcgi start

11. Restart daemons and visit your munin site


/etc/init.d/nginx restart

/etc/init.d/munin-node restart

Go to


Check how to add dewpoint graph on my next post.



My HW/SW setup:

Dongle: SDR USB Dongle (Realtek RTL2832U R820T chipset, other SDR dongles may also work). Search Ebay for RTL2832U dongles. They should all work.

OS: Windows 7, 64bit

Capture software: SDR# from

Decoder: AFSK1200

Note: Don’t install any software drivers that came with the SDR Dongle. Uninstall the drivers, if you already installed them.

1. Setup stereo mix:

Stereo mix is used to forward output sound to the microphone input. We need this, because AFSK1200 decoder will be listening to the microphone input. Open sound options in control panel or just go to start and enter mmsys.cpl. Using USB headset will not work, you need analog speakers. There are some workarounds to use USB headsets but I haven’t tried them yet.

Playback tab: set speakers to the default device.


Recording tab: if you don’t see the “Stereo mix device”, it’s probably hidden.

  • Right click anywhere in the field where devices are listed and tick “Show disabled devices“, “Show disconnected devices. Stereo mix shold be available now.
  • Right click on it and select “Enable“.


2. Download  and configure SDR# software:

  • Download
  • Extract it and run install.bat
  • Plug in your SDR dongle, go to sdrsharp folder and run zadig.exe. Go to Options and tick “List all devices“. Select “Bulk-In, Interface (Interface 0)” and click “Install Driver”. (On my screenshot, you can see “Reinstall Driver, because I already installed it). Note: You will need to install driver again if you replug the dongle in another USB port.


  • Run SDRSharp.exe
  • Source -> RTL-SDR (USB)
  • Radio -> NFM, enable Squelch and set it between 50 and 80, you can increase or decrease it depending on your surrounding environment
  • Frequency Manager -> New -> add the frequency you want to monitor, in my case it’s 144.800 Mhz.
  • Click on Play button at the top of SDR# You will see spikes when something is transmitting on the frequency


3. Decode packets with AFSK 1200 Decoder:

  • Download AFSK 1200 Decoder
  • Select Input and choose Stereo mix
  • Click play button. You are now decoding APRS packets


Don’t forget to disable stereo mix and set the default playback device as you had before when you finish decoding.

I used my RaspberryPI to setup an APRS digipeater. The software I used is called Xastir. The problem is, there are no good default maps to use in Xastir.

This tutorial will guide you how to install OSM maps into Xastir software. Maps are generated on a Windows machine, then transferred to a Linux machine where Xastir is running.

TL;DR version:

1. Download Taho application for Windows.

2. Select area, copy bbox text.

3. Paste bbox text to Taho, click on bbox button, select parameters and click on make maps.

4. Upload generated .inf and .jpg files to your Xastir map folder.

5. Download to your linux machine and convert .inf files to .geo files.

6. Start or restart Xastir, select your map and apply.


Detailed version:

1. Download Taho application for Windows (Version 4.01 didn’t work on my PC, you should download older versions, if you can’t run the newest version).

2. When you launch the Taho application, it will also open the bbox tool site.

3. On the bbox tool site, center map to your desired location and click button “select area”. Select your area.

Note: If you select too big area, you won’t be able too select top zoom levels in the next steps.


4. Copy code in the grey box to your clipboard.



5. Open Taho application and paste the code into “Get from <bbox…>” field. Click on the bbox button now. It should populate coordinates into Taho application. Select UI-View in Kal.-Files, .jpg for file type, zoom level (16 is good for small city), size (should be free, whole area in 1 file), define path for saving your maps and click on make maps button.



6. Each selected zoom level generates separate .jpg and .inf files in your defined maps path (step above).

7. Xastir doesn’t know how to handle .inf files so we need to convert them to .geo format. Upload your .jpg and .inf files to Xastir map folder. In my case, maps are located in  /usr/share/xastir/maps Fire up your linux console and

Download converter and convert .inf files:

sudo cd /usr/share/xastir/scripts
sudo wget
sudo chmod +x
sudo ./ /usr/share/xastir/maps/yourmap.inf

By now, you should have yourmap.geo file in /usr/share/xastir/maps
Open .geo file with your favourite editor and correct the path if you have to.

FILENAME    maps/yourmap.jpg
TIEPOINT    0           0       16.0645 45.8288333333333
TIEPOINT    5631        5887    14.661666666667        46.8525
IMAGESIZE   5632        5888
# Converted from a .INF file by WE7U's script

Note: If you change the name of the file, you also have to change FILENAME in yourmap.geo accordingly.

8. Start or restart Xastir, go to Map -> Map Chooser -> select your map -> Apply -> profit.