For this week's assignment we need to design and create a board that has a sensor or some device that send signal back to the attiny to be processed. I decided to design a circuit with a temperature sensor, I wanted to build something like a termometer. For this I decided to use the SMD thermistor we had in the Lab.
You can file the data sheet here. The sensor used is the SMD NTC 10K 1206 Thermistor.
Then I took the project to the Eagle software to be designed. For this design I took into consideration some aspects of how this board will work. Because this will be uploaded with a programmer as an ICSP, in this case I can't count with the serial communication to display results from the sensor. So with this in mind I decided that I wanted to have two leds with different colors to display if the temperature is below or above certain number. This will be integrated in the design. I can design the board to communicate with serial but it will be much harder.
The image above shows the board design that was made in eagle. We can see that we are using an Attiny 81, the 6 pins for programming it, the thermistor with its resisntace and the two leds, each with its resistor.
The image above shows the board already in place to be manufacture, we can see that it looks all tidy and functional, the size is also small. We are ready now to send it to the mini milling.
After the milling process the board looked like this:
Then we soldered the elements.
The program was built in arduino. It will work detectin higher temperatures. Without the temperatures one led is turn on, when you put a candle close to the sensor, the other led will turn on. We can see the arduino code below.
Now we can see how it works.
In the video we can see the board functioning correctly.
You can download the code from here.
