Is it possible to scale analog input voltages

[Guest ahayter]

Hi! I just built my first MIOS core and AIN. So far so good. However I have been trying to use an infrared sensor as an analog voltage source. It works (although it is a little shaky - the voltage is not very steady), but the infrared sensor only outputs 2.5v max, so I don't have full range of motion on faders, etc... I was wondering if it is possible to scale the input (I know I would lose 1/2 my resolution but I don't care, I am using it to convert dance motion into MIDI and the resolution does not need to be that high.) Or will I need to amplify the signal and if so is there an easy way to do this that you can suggest. Also is there a way to to smooth the input signal (do I use the Deadband setting to do that, again I don't care if I lose resolution)

Thanks for your help,

Andre

[pay_c]

Possible hardware solution: Use an OpAmp to double the voltage. Easy schematic. Available in nearly every electronic book.

Greets.

[Duggle]

yes, this is very easy, just a hint, if you are going to power the op amp with the 5V supply common to the rest of the circuit, you should use a rail to rail op amp (capable of outputing voltages from close to 0V up to close to 5V).

[Guest ahayter]

Thanks for the hints guys. I'll try that.

Andre

[Bass_MIDI]

HI

Hey i am trying to do the same thing  (using an infrared sensor on AIN module) , but i don't have any idea of how to do it . Could you please post some schematics of your circuit or maybe a link?

Thanks!

[moebius]

Just google for "non inverting opamp" ;)

Bye, Moebius

[SexyBeast]

Hi,

regarding the 'shaky' voltages from the infrared sensor: you could put a small capacitor in parallel, this would surely suppress too quick changes in voltage. But I really can't tell you which capacity to use - you'll have to experiment...

regards, tom

[Guest ahayter]

Hi Bass_MIDI,

I am using sensors from www.junun.org/MarkIII they sell parts for making robots and have very good prices. I am using the Sharp GP2Y0A02YK Distance Measuring Sensor - it has the greatest range, there is a variety of ranges. Be sure and get the JST 3-pin cable if you buy one it saves a lot of trouble. You just connect the the power and ground wires to power and ground of J5 on the core module and the output wire to one of the analog inputs on J5. Upload a test program like AIN example 1 and you should get midi by waving your hand. I will upload a fuller description once I get the op-amp and the capacitor circuit worked out.

Andre