Setting a wireless access point for the beaglebone black

It should be easy if we get the right usb dongle. So far we have tried 2 different realtek types and they fail miserable with the existing open kernel drivers. Not going to compile crap kernel modules and use hacked ancient versions of hostap, thanks

Our last purchase which is a “TP-Link TL-WN722N” should hopefully be an atheros chipset which we always had great experiences with.

Well the previous two we bought were supposed to be atheros but only until version 3. The ones we received where version 4…

If this works it will be great. It also has external antenna connection.

 ***UPDATE***
 And it does work out of the box ...

setup

Assuming that a bridge is setup already with the wired interface in it and something like dnsmasq is serving ip addresses all needed for it to work is:

1

aptitude install  hostapd  haveged firmware-atheros

Haveged is a daemon that helps providing entropy for our wpa ap.


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16

  egrep -v '(^#|^\s*$)' /etc/hostapd/hostapd.conf
  interface=wlan0
  bridge=br0
  driver=nl80211
  ctrl_interface=/var/run/hostapd
  ssid=boat
  hw_mode=g
  channel=1
  wpa=2 # This sets the security settings to WPA2
  wpa_passphrase=hackme
  wpa_key_mgmt=WPA-PSK
  wpa_pairwise=TKIP
  rsn_pairwise=CCMP
  beacon_int=100 # This sets how often the WiFi will send a beacon out.
  auth_algs=3
  wmm_enabled=1

Start the services

1
2

service haveged start
service hostapd start

We also need a couple of iptables rules for NAT:

1
2
3
4
5
6
7
8
9
10
11
12

#!bin/bash
iptables -t nat -F
iptables -F
echo 1 > /proc/sys/net/ipv4/ip_forward
LAN='br0'
WAN='usb0'
iptables -t nat -A POSTROUTING -o $WAN -j MASQUERADE
iptables -A FORWARD -i usb0 -o $LAN -m state --state RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -i $LAN -o $WAN -j ACCEPT

ip route del default
dhclient $WAN

The $WAN interface could be anything that the internet is plugged in. In our case a 4g usb dongle on usb0. We add this to /etc/rc.local before the exit 0 line at the end if it exists.

1
2
3

...
sh /root/bin//masq.sh
...

Anton spent three weeks in Croatia near the city of Gračac in a very beautiful region participating in MMKAmp. This is an international camp on the theme “Future Environments” for people interested in ecology, autonomy, sustainability, low impact living, technology and DIY culture.

The heart of the camp was a hand made geodecic dome with solar panels and satellite internet.

It was also the first opportunity to test my boattr mobile box in the field there and Anton was quite pleased about the results.

Apart from being very usefull keeping all electronics and laptop charged in the middle of nowhere (Anton could only use the laptop 2 hours a day but this is not bad at all), Anton also did some small improvements in the code and the construction and finally got to show it to people for the first time.

A hardware/software research project into the management of off-grid, autonomous sites. It collects and processes data from enviromental sensors and provides remote monitoring, control and automation.

Optionally it can also provide a host of other peripheral services that can run on the small embedded computer (wireless AP, internet connectivity, vpn remote access, tor gateway, file storage etc)

why was it made?

Since living off-grid Anton realised that he was lacking good information about the energy consumption and production, battery health and the various other subsystems of the boat.

One part of the project is about being able to better understand how those systems work by collecting, analysing and visualising their data.

The other interesting aspect is using realtime information from the sensors as well as historical data to make clever decisions and respond to external changes.

It seems that there was no free software based solution to fit my needs so Anton decided to Do It.

collecting data

At this point boattr has current, voltage, temperature and water pressure sensors. Data is collected from the sensors and stored in a db every minute. We can create real time graphs as well as mine the database for other historical data.

The heart of the system is a beaglebone black ARM embedded computer running Debian. Most of the sensors are analog and connected via a 10 channel ADC => I2c IC.

The temperature sensors are using the 1wire interface and one can read more details about the 1wire setup

Current sensing using the bidarectional allegro acs714 hall effect sensors using the breakout board from pololu

Voltage using a simple voltage divider

the software

The software part of boattr is made of a ruby module with two classes, Sensors and Data and the puppet provisioning code. The Sensors class contains all the functionality to obtain the results from the the various different sensors connected to the system.Data is responsible for processing resulting data, saving and sending to other places.

Here is an example of a box called ‘brain01’ on the boat retrieving data from the sensors, sending them to the database and real time graphs.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36

#/root/boattr/boat.rb
require '/root/boattr/sensors.rb'
hostname = Socket.gethostname
p hostname

brain01 = {
  'description' => 'analog/i2c from brain01',
  'basename'    => 'boat',
  'i2cAddress'  => 0x28,
  'i2cBus'      => '/dev/i2c-1',
  'couchdb'     => 'localhost',
  'dashboard'   => 'localhost',
  'graphite'   => '10.70.60.1',
}

sensors=Boattr::Sensors.new(brain01)

brain01_sensors =
  [ sensors.current('solar',0),
    sensors.current('generator',1),
    sensors.current('lights',2),
    sensors.current('pumps',3),
    sensors.current('ring',4),
    sensors.current('fridge',5),
    sensors.voltage('batteries',6),
    sensors.waterlevel('tank',7),
    sensors.temperature('out','10-000802964c0d'),
    sensors.temperature('in','10-0008029674ee'),
    sensors.temperature('cylinder','10-000802961f0d'),
    sensors.temperature('stove','10-00080296978d'),
    sensors.temperature('canal','28-000004ee99a8'),
]


Boattr::Data.new(brain01).to_db(brain01_sensors)
Boattr::Data.new(brain01).to_graphite(brain01_sensors)

A cron job will run the above code every minute saving json formatted documents on an instance of couchdb as well as real time graphs using graphite.

Puppet is used to configure the system, install packages, configuration files and cronjobs:

1
2
3
4
5
6
7
8
9
10
11
12
13

node brain02  {
  $subnet     = '192.168.8'
  $domain     = 'camp'
  $ip         = "${subnet}.99"
  $br_iface   = 'br0'
  $wifi_iface = 'wlan0'
  $ssid      = $::hostname

  class { 'dnsmasq':  subnet => $subnet, interface => $interface }
  class { 'network::ap' :  ssid => $ssid, wifi_iface => $wifi_iface }
  class { 'network::interfaces' :  }
  class { 'couchdb': }
}

The graphs look like this:

dashing is in the works.

The code is available on github

apt-get update
apt-get install puppet git librarian-puppet

cd /root/
git clone git://github.com/galp/boattr.git
cd boattr

librarian-puppet install

puppet apply --modulepath="/root/boattr/provision/modules/:/etc/puppet/modules/"  --hiera_config="/root/boattr/hiera/hiera.yaml" --verbose  provision/default.pp

Anton and Adnan installed the boattr microcomputer on Quintessence. Now there are two boattr boxes on the UK Waterways (Blue Morn & Quintessence). boattr runs on a beagle bone black.

The Construction of a Boattr Box

Powered Usb Hub for Beagle Bone Black

Another long term todo item ticked today. Adding a powered usb hub to brains , having only one port which was permanent taken by the 4g modem was not very helpful.

Now we can have 4g modem, 3g phone, usb interface for permanently connected stereo hydrophone, wireless and an external hard disk.

Our previous attempt to do so ended up with a fried hub , beaglebone and wireless dongle when accidentally wired the usb hub power to 12v instead of 5V.

Yesterday Anton popped to maplins and got a 4 port cerulian usb hub. Plugged it in and it didn’t work. Anton was very suprised that something as simple as a usb hub would not work. After searching on the internet Anton found that this is a known issue.

The solution is to open the hub and cut the red cable therefore stopping the hub from providing power to the beaglebone.

All working now it seems. Great stuff.

And the installation of the boattr box on Quintessence (using a beagle bone micromputer and a 4G phone, all connected over a USB hub and WiFi access point):

One Wire Network

With boattr we use Dallas 1-wire microlan for a network of temperature sensors. With this post we will make an attempt to document it. Not trying to explain what 1-wire is as it is documented elsewhere on the internet.

1-wire is a very simple communications protocol for sensors. The beaglebone black has two i2c devices ( /dev/i2c-0 and /dev/i2c-1 ) and we are using ‘/dev/i2c-1’. In order to get it to work we will have to add a custom device tree. We did this by reading this very helpfull blog post

For debian the dtc -O dtb -o BB-W1-00A0.dtbo -b 0 -@ BB-W1-00A0.dts command fails because a patch is missing. The easiest way to get around this is to download a patched version from here and use that instead.

• Copy paste the code in the dts file
• Compile with dtc command above
• Copy resulting dtbo file to /lib/firmware
• Add ‘’‘echo BB-W1:00A0 > /sys/devices/bone_capemgr.9/slots’‘’ to /etc/rc.local
• Restart

( All the above should be done by puppet for boattr)

The information from the sensors appear in special files under /sys/bus/w1/devices/$ID/w1_slave. Reading /sys/bus/w1/devices/$ID/w1_slave gives as the temperature value in C.

Each sensor has a unique 64bit id that we can use to address it :

1
2
3
4
5

sensors.temperature('out','10-000802964c0d'),
sensors.temperature('in','10-0008029674ee'),
sensors.temperature('cylinder','10-000802961f0d'),
sensors.temperature('stove','10-00080296978d'),
sensors.temperature('canal','28-000004ee99a8'),

The temperature method looks like this :

1
2
3
4
5
6
7
8
9
10
11
12

def temperature(name,address)
  @name     = name
  @address  = address
  @basedir  = '/sys/bus/w1/devices/'
  if @@OWdevices.include?(@address) then
    file = File.open("#{@basedir}/#{address}/w1_slave",'r')
    if file.readline().include?('YES') then ## Is CRC valid in the first line? lets read the second and extract the temp
      @temp = file.readline().split()[-1].split('=')[-1].to_i/1000.0
      return { 'name' => @name, 'address' => @address, 'type' => 'temp', 'value' => @temp.round(3) }
    end
  end
end

Hardware

The sensor used is the DS18S20 datasheet.