Fusion Brain Analog Accuracy and Error Detection

**DJiK** · 06-07-2008, 11:50 PM

After a few hours of trying to figure FB out, I was finally able to retrieve analog values off the accelerometer (#A54621).

However, I noticed that when I plug in any given axis, the analog values of the remaining 9 inputs start jumping up and down.
What's more, the closer I check to the analog input I'm actually using, the higher the fluctuations of the empty analog inputs.
Id est, if the input I'm using is Analog #5, then numbers 4 and 6 are the loudest (though they are not connected), and 3, 7, 2, 8, 1, 9 get quieter and quieter, respectively. By loud or quiet, I mean the signal strength as compared to the actual analog input being used.

I used to believe that each analog input channel is independent of its neighbors, but with today's experiments, it is clearly not the case.

For the life of me, I cannot figure out how to use the MDX software to create a new test application. If you'd reply with a quick tutorial on how to log data from each individual analog input, I'd be able to back my words up with some numbers from the accelerometer's log.

**mx270a** · 06-08-2008, 12:10 AM

Put a jumper between ground and the signal pin on the input after the one you're reading. If you're reading input 5, ground out 6.

The inputs are all read by the same analog to digital converter, sequentially. The inputs by themselves have no resistance to drain off voltage, so the voltage from one input will carry over to the next input as they get read.

It really shouldn't matter though because if you don't have a sensor attached to those inputs, you probably don't care what value they are at. In the test mode when you can see all input values, then you will see the voltage carry over.

**2k1Toaster** · 06-08-2008, 12:32 AM

also with a sensor connected, it will discharge it correctly, and you wont get that carryover. So it is only an "issue" for non-used inputs.

**2k1Toaster** · 06-08-2008, 04:05 AM

Originally Posted by DJiK

For the life of me, I cannot figure out how to use the MDX software to create a new test application. If you'd reply with a quick tutorial on how to log data from each individual analog input, I'd be able to back my words up with some numbers from the accelerometer's log.

Well easiest way to display everything at one time is using the virtual brain. To save it for later you can use a log.

Easiest way to do a log:
1) Create a Fusion Brain instance
2) Create an Analogue Input Instance for each port you want to log. Notice that you have to set the brain id to the brain created in (1) and each port should be different. To monitor all 10 ports, instance #1 should have a port of 0, instance #2, have a port of 1, and instance #10 should have a port of 9.
3) Create a Log Instance for each port you want to monitor. Set the what to monitor to be an analogue input, and set the target id to the name you gave each of your analogue input instances in (2).
4) save and be done.

**greenman100** · 06-08-2008, 11:50 AM

Or, you could look in the skins section, and use the logging example.

http://www.mp3car.com/vbulletin/skins/

come on guys, do a LITTLE work here

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