Assignment 11 Input Devices

In this weeks Assignment we had to add an analog sensor to our boards and read it. We also had a group assignment in which we had to measure analog and digital input signals the results can be found here.
I decided to make a circuit with an led that lights up when my tea has a drinkable temperature.

Tools used

• 1x ATtiny44
• 1x 100nF SMD Capacitor
• 1x 2x3 SMD Pinheader
• 1x red SMD LED
• 1x white SMD LED
• 2x 150Ω Resistors
• 1x 10kΩ Resistors
• 1x 4.7kΩ Resistor
• 1x 4.7kΩ Thermistor
• 1x 1x6 Pinheader
• 1x Arduino Uno
• Jumper Wires

Testing the Sensor

First I connected the sensor to my Arduino nano to get a feeling for the values the the sensor provides. I tried different resistors and found out that the best values where achieved with a 4.7kΩ resistor for the 1x 4.7kΩ Thermistor.
To test the Thermistor I used a cup with boiling water and hairdryer.

Making the Board

Here I simply modified the eagle files for the hello-world-board and exchanged the button with the thermistor circutery.

The board layout was also really easy to make because I just had to modify the hello-world-board.
I milled and soldered the board like the others detailed instructions can be found here.

Programming the Board

To program the board I used the same setup I used for the hello-world-board detailed instructions can be found here. I tested a few values so the Light goes off when my tea has a drinkable temperature.

To check the temperature I am using the raw analogue data that i get from the sensor. Usually its a value from 1 to 1024. When using the Arduino IDE you can simply read the data withe the analogRead command. For better results you can try to filter the raw data because there can be a lot of noise, in my case that was not necessary.