LED Spectrometer

The Led spectrometer is an open-source project. The aim is to dectect molecules in liquid. This project is based on raspberry Pi commanded by an 5'' display screen. The Raspberry controls by an node.js server and his module : Johnny-five an arduino mega to control LED, servo and photoresistor. The datas are displayed in real-time on the screen.

Getting Started

## Prerequisites

	### hardware

• Raspberry Pi 3

• Arduino Mega

• 5'' HDMI display screen

• servomotor

• breadboard (adafruit perma-proto for me)

• LED (wave-length adapted for your search)

    ### installing
  

• up-to-date raspbian

• VNC servor : X11vnc sudo apt-get update sudo apt-get install x11vnc x11vnc -storepasswd

• 5'' display screen

  • /boot/config.txt device_tree=bcm2710-rpi-3-b.dtb dtoverlay=ads7846,penirq=22,speed=10000,penirq_pull=2,xohms=150 dtparam=spi=on hdmi_group=2 hdmi_mode=1 hdmi_mode=87 hdmi_cvt 800 480 60 6 0 0 0
  • touch screen settings sudo apt-get install autoconf libx11-dev libxext-dev libxi-dev x11proto-input-dev cd ~ wget http://github.com/downloads/tias/xinput_calibrator/xinput_calibrator-0.7.5.tar.gz tar -zxvf xinput_calibrator-0.7.5.tar.gz cd xinput_calibrator-0.7.5 ./configure make sudo make install DISPLAY=:0.0 xinput_calibrator write values in /etc/X11/xorg.conf.d/99-calibration.conf

• install node.js
  * check version of node on your Pi : node -v * check Pi caracteristcs : uname -a * you need the 4.2.1 for johnny-five wget https://nodejs.org/dist/v4.2.1/node-v4.2.1-linux-armv7l.tar.xz tar -xvf node-v4.2.1-linux-armv7l.tar.xz cd node-v4.2.1-linux-armv7l sudo cp -R * /usr/local/

• install arduino IDE sudo apt-get install arduino arduino

• install nodejs modules sudo npm install johnny-five sudo npm install express sudo npm install ejs sudo npm install socket.io

• install firmware on arduinoMega : in IDE Arduino

npm install -g forever

• Install forever-service : to start node.js on each boot on spectrometer.js

npm install -g forever-service

sudo forever-service install spectrometer --script /home/pi/Desktop/spectrometer.js

sudo service spectrometer start

• copy files and folder on Desktop : you must change on spectrometer.js file : photoresistor pin line 41, servomotor pin line 47

• reboot

  Running the tests

• the screen on boot shows spectrometer home page. The servor uses Chromium in kiosk mode. You may connect with a browser to the IP raspberry : http://how.do.you.troll.biz/

• Learn french language and push on Lancer le programme

• you must set up :

  • LED color
  • angular measurement of servomotor : it's the angular value where the LED is in front of the cuvette.
  • LED pin on the mega

• push on lancer l'analyse

• after page reboot, the values are showed at the bottom on the graphic.