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AtTiny Development Board

When a 28 pin Arduino just won't do for your small project. Consider a 8 pin device the AtTiny85. I was ask if i could develop a motor controller that used an output from a cars engine to control an air pump that would control the flow of Fuel/Water Vapor.

I looked at the possible outputs that a petrol engine would provide as a good feed back loop and this is what I came up with.

  • Throttle Position
  • RPM
  • Vacuum

I analyzed each of these options and decided that vacuum would be the most responsive and the simplest to implement.

Now I need a good power supply to provide the micro controller & vacuum sensor with 5Vdc. When developing a new design, it helps to use circuits that are already tested and operational. so I took a H2O2-PWM Plus V2 PCB and made a simple change to the 10V DC regulation circuit. I replaced the regulator with a 5V 7805 regulator, now that was easy.

       
          The H2O2-PWM Plus V2 is
            only used for prototyping.

Now I need a MosFet to control a motor, I had on the bench a circuit that I use to test my finished PWM V2 Boards. It really is just a MosFet and some traces and wires to connect up to, but perfect for this application.

       
               MosFet Test Fixture.

I proceeded to connect up the AtTiny85 to the 5Vdc, I connected 2 potentiometers, and the vacuum sensor to the analog inputs. Then I connected the MosFet to the PWM output. I used a simple green proto board I had made to connect it all together.

     

                          Pin out of a AtTiny45/85

 

      

         The AtTiny85 and the Vacuum sensor.

I followed the instruction at High-Low Tech, a research group at the MIT Media Lab to program the AtTiny85 with the Arduino board. This connection is explained at High-Low Tech and requires 4 wires plus Ground. I had the Blink Program working in just minutes and a Proto Program written and working in about 30 minutes.

Now it time to test this newly created device, here is a video that I have connected this device up to my car engine. It is hard to tell what is happening, but you can hear the PWM frequency increase as the engines RPM increases. In an engine the vacuum is dropping as the RPM increases so the relation is inversely proportional.

    

 

More to come soon.