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jadonk / bonescript

Scripting tools for BeagleBone and PocketBeagle
http://beagleboard.org
MIT License
514 stars 159 forks source link

analogRead (and other) documentation #160

Closed troywweber7 closed 6 years ago

troywweber7 commented 6 years ago

This is just a minor feature request for better api documentation (either in a README or as a JSDoc for each function).

As an example, regarding analogRead, I noticed that it divides a reading by 1800 in the code and I'm confused about why because I thought the ADC's were 12-bit which would lead me to believe one should be dividing a reading by 4096 (2^12).

Perhaps I am wrong about that last part, but I am still left thinking "When I do an bonescript.analogRead('P9_39') how do I map that value? Am I assuming correctly that the analogRead function returns a value of 0 ≤ VALUE < 1?"

fivdi commented 6 years ago

The code that's used by analogRead today is here. It uses 4095 (2^12 -1.)

The code you link to above is from a long time ago. Back then the raw analog values returned by the driver were value between 0 and 1800 (inclusive.) It's a millivolt value. The maximum value that can be input on analog input pins is 1.8V which is 1800 millivolts.

troywweber7 commented 6 years ago

Thanks for pointed to the proper code. @jadonk, I think it still might be a good idea (in a README for example) to document each of these functions unless they going to change drastically in the near future.