The Deployment of Aalto Explorer V 1.0 (Part 2)

LED LIGHTS: CONNECTION AND CONTROL

Description

Led lights were controlled from the Raspberry through the Arduino board, which enables the high power (12v) to feed the lights.

Steps/Diagrams

After the Arduino digital output, a set of NPN transistors were used in switch connection mode to allow the feed.

 

RASPBERRY-LAPTOP COMMUNICATION

Description

To configure and to get the system working, different communication channels were established: Wifi hotspot from the computer, from the raspberry and an Ethernet network.

1. Ethernet Connection to Linux (Laptop, Asus)

The first attempt to connect to raspberry was through a shared ethernet connection. In Connections –> Edit Connections –> Ethernet –> Edit –> in ipV4 settings set Method to ‘Shared to Other Computers’

That creates an automatic DHCP server in the Ethernet port, hence, only connects an ethernet cable from the linux laptop to the raspberry

Knowing ip address assigned to the raspberry

To know the ports configuration in the linux laptop: ifconfig

From there, we know the network created in the ethernet port. In this case it was 10.42.0.1.

Then, to scan the network (across all devices): nmap 10.42.0.0/24

This gives the up-hosts.

Next, ping, or connect through remmina desktop (in every ubuntu computer by default), or later with RealVNC (once installed), or plug in an HDMI monitor.

2. Wifi Hotspot from Linux laptop

We need a Wifi port which will be the hotspot. If we want internet connection, it should be provided from Ethernet or another Wifi dongle must be used. There are other configurations for using the same wifi spot for server/client, but we’re not going into that by now.

In Linux laptop: Edit connections: Add –> Wifi –> create

the SSID is free to choose, in this case it was set to HelloPi!

Mode: Hotspot

Device: the Wifi HW we will use

Wifi security: wpa & wpa2 personnel — and set a password: raspberry0.

ipV4 settings: shared to other computers

That will also share the internet connection.

Once done, reset the network manager: sudo service network-manager restart and connect to the network. If not visible, go to “hidden network” and select the SSID. Once the connection is acknowledged, go to the raspberry and connect to the network.

3. Connect to Wifi Network from Command line

Option 1

Edit /etc/network/interfaces and write:

auto wlan0

iface wlan0 inet dhcp

wpa-ssid {ssid}

wpa-psk {password}

After that write and close file and use command:

sudo dhclient wlan0

Replace {ssid} and {password} with your respective WiFi SSID and password: HelloPi! and raspberry0.

Option 2

Provided that you replace the Wireless network card, Wi-Fi Network name, and Wi-FI Password this should also work.

We were using: – Wireless network card is wlan0 – Wireless network is “Wifi2Home” – Wireless network key is ASCII code ABCDE12345

First, get your WiFi card up and running:

sudo ifconfig wlan0 up

Now scan for a list of WiFi networks in range:

sudo iwlist wlan0 scan

This will show you a list of wireless networks, pick yours from the list:

sudo iwconfig wlan0 essid Wifi2Home key s:ABCDE12345

To obtain the IP address, now request it with the Dynamic Host Client:

sudo dhclient wlan0

You should then be connected to the WiFi network. The first option is better, because it will be able to run as a cron job to start up the wifi whenever you need it going. If you need to turn off your WiFi for whatever reason, just type:

sudo ifconfig wlan0 down

Results

MOTORS CONTROL

Description

They are controlled through a serial communication towards the Arduino board, and from there, a PWM scheme is used. The width of the pulse is controlled from the raspberry. After the digital output in Arduino, a full bridge (L298D) is used to plug the power for the motors.

UNTETHERING POWER SYSTEM

Description

Since the components use two voltage sources (5v @ 1Amp for the raspberry and 12v for the lights), a step-down converter was used to adapt both voltages and hold the current for all the components.

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