Assignments

Add a sensor to a microcontroller board and read it (week 11, input device)

Add an output device and program it to do something (week 13, output device)

Input

These are two diffucult assignments for me, because I don't know much electronic, but I will try to produce something useful to my final project: I would activate some effects (hot, cold, air) when you touch a zone, so I thought that a photoresistor is a good solution to read hand proximity.

So I started from Hello.light example and I tried to copy it, but we have Attiny44 instead of Attiny45 here in FabLab Torino: I had to download the datasheets (Attiny44 , Attiny45) and compare them.

I know that the next method is not professional, but I'm a beginner in electronics so it's the only I found to make the assignment my self: I looked at an Attiny45 pin in Hello.light board, then at that Attiny45 pin in its datasheet, finally I looked for the same pin in Attiny44 datasheet.

For example, in Hello.light board PB1 goes to MISO of pin header --> PB1 in Attiny45 has (MISO) --> (MISO) is PA5 in Attiny44 --> in my board PA5 has to go to MISO of pin header!

In this way I added a photoresistor, now I have to add a little fan. I looked for a fan inside Eagles libraries..fortunately a friend told me after many minutes that I have not to find "fan" component but a generic connector...I'm a real beginner, damn!!

Update

I changed idea: I will make a board just for 3 input, and then I will make another one just for output.

After many hours at working, this is my final scheme, his board and finally his nc file ready for milling.

Correction!

Terrible mistake: I made my board looking at Neil's example, but I forgot different pinout of microcontrollers; in particular, I connected the photoresistors to pins without analog input!

In order to save this board and begin to do some tests, I will connect pin 5 to pin 6 (which has ADC). Thanks to my classmate Gianfranco Caputo for all the help!

Programming

I decided to program my board by an Arduino Duemilanove as ISP programmer.

First I looked for how to connect them and I found this useful page.

In another section of the same page I found how to program my attiny: just following this tutorial step by step, I was able to do everything!

In this way, I could write a sketch in Arduino to set the actions of my Attiny.

Advice 1: remember that Arduino pin-out is different from Attiny pin-out (thanks Gianfranco Caputo!): for example, I connected a photoresistor to pin 6 of Attiny, but in the sketch, Arduino will need to call this pin "pin 7"!

Advice 2: Attiny44 hasn't got an hardware serial port, so I need to create a virtual one. I found this example and I wrote these commands.

Finally I compiled the sketch, its goal is to show different values on my screen, depending on the light that hits the photoresistor: here the final sketch. The loading was successful.

Last step: test my little board in action! I connected it with usb cable, I downloaded HTerm (just a terminal software), and I covered/ uncovered the photoresistor...this is the result:

I forgot to insert a delay, so the input board sends values too quickly, however in this video you can see that the board works:

Output

I decided to create an output board, with 2 leds, 2 fans and a Peltier cell.

With this thing in mind, I looked at week 06 (electronics desing) and added 2 leds; other outputs need just a pin header 2X1 (1 pin for vcc, 1 pin for ground). In order not to make further mistakes with pins, I looked for Attiny pinout to be sure of digital/analog outputs.

As you can see, no problems for choosing which pins have digital signal.

So I drew my board:

Here the scheme, the board and finally the .nc file for milling.

In order to test the output board, I loaded into it a simple sketch to turn on leds and fans depending on chars received from input board: at the moment, just remember that output board gets chars from its serial port (for details, let's go to week 15).