Need better accuracy with TI Launchpad?


We just started using the TI Launchpad and we have a problem with our 12 state rotary switch. The problem is that there only seems to be a handful of values the NI Joystick Explorer sees which are .094, .1, .11, and .12. This is a problem because we really want to use all 12 parts of the switch. I know the switch works because I tested it on the Arduino Analog port and all 12 states were at different numbers. We are using the 3.3V rail on the Launchpad. Is there something extra you have to do in order to make it so it reports very precise voltages?

Thanks a bunch in advance!

You probably just need to calibrate it. From your start menu, search for and open “game controller” and you should see something along the lines of Game Controllers (win7) or Setup USB game controller (win10). When you open it, you should see the LaunchPad listed, along with any other controllers currently attached. Go ahead and select it, and click “Properties”. Open the settings tab, and click “Calibrate”. It will open a wizard, just move turn the rotary switch back and forth until you can identify the axis it is associated with in Windows. When you are at the right screen, just turn it all the way from one extreme to another, and it should calibrate the full range for you.

Another tip, make sure to use the 3.3V VCC line from the launchpad, and not the 5V line. The 5V one could damage the analog input.

Thanks for the tip. It worked using calibration for the rotary switch. The only problem is that all the other axises are going completely crazy. This doesn’t really matter since I will only ask for the axis that I need, but it is kinda strange…

The reason for this is the “min” and “max” calibration values for those axis are nearly identical, so noise in the input is being read as different values. It’s not an issue, but if it bothers you, the easiest way to fix it is to just tie all the inputs together (e.g. tie them all to the rotary switch).

The noise is also going to be increased since it’s a floating pin. You can also tie the unused inputs to ground to get rid of the jitter you’re seeing.