The "Ultimate" Raspberry Pi - With analoge stick

There are two approaches. One you tried using an intermediary process (attiny). Here you need to "scale" the results to say 0-1024 matching 0-3.3v. Your results above is not to bad. The other way is use analog signal and measure the characteristics of the circuit. This article shows how: Conventional Analog: Into Digital - How Joysticks Work | HowStuffWorks . The Pi can handle this case directly and measure time to register a +1. Trick is setting the capacitance to a high enough value but not too high. This affects the speed versus the sensitivity(range of values). I am planing to use this design in the near future.

Clem

But should i not get 0-1024 by using a 3.3v supply to attiny and to the joystick? jumping VCC to A0 gets 895 on analogread, and jumping ground gives 0. Thought i'd get 1024 on 3.3v since thats the only ref the unit have ?

The aref voltage affects the range you get. If the voltage at aref is higher than 3.3v, I can see a number lower than 1024 even if the measured voltage is 3.3v. The circuit is a comparator between voltage between aref and measured input to determine the digital number returned.

Clem

Edit: You need to measure the actual voltage at the inputs to the ADC.

That is correct other than the voltage given to the chip is 3.3V no 5V even close to it. So 3.3 should be the reference on attiny since i power it with that?

1024 / 5V * 3,3 = 675,84 is not 895 so it could not use 5v as reference

Also it sometimes gives 1024 like.. 5-10 times each 5sec out of a couple of hundreds pr 5sec. I dont understand how it gets 895 instead of 1024. The button sends 1024 but the X and Y axis are 0-895 both of them.

Without a schematic and pictures, I cannot correlate what is happening. I do know the theory of what should be.

Thanks,

Clem

Without a schematic and pictures, I cannot correlate what is happening. I do know the theory of what should be.

Thanks,

Clem

Found out a problem now. I made a variable (X) increment from 0 to 1024 each time i asked for data via i2c and i see that it loops back to 0 on 895. So its code related not hardware.
It counts from 0 to 895 then from 0 to 127. Probably something wrong with my i2c byte thingy then

Arduino: (This increments x from 0 to 1023 and resets it.

      int a = 1024;

      if ( x >= 1024) x = 0;

      if(digitalRead(Z_AXIS)) { a = x++ ; }

      TinyWireS.send( highByte(a) );

      TinyWireS.send( lowByte(a)  );

Python: This receives the two bytes and adds them to a number i thought

  Hi = bus.read_byte(address) # Read the High byte of the frame

  Lo = bus.read_byte(address) # Read the Low byte of the frame

  return (Hi << 8) + Lo # Convert to number

This makes sense. The hardware was so unclear to me as you described it. The facts you claimed was a non sequitur to reality.

Clem