Scaling analog values

[Eric Williams]

I'm using the Crestron Mobile V3.4 with a particular gui.  I have a 16bit analog value coming in (volume gauge). I would like this to be displayed as a percentage 0-100% on a serial join.  I already have a function triggering when the join changes that uses parseInt to return a value.  Is there a easy way to simply convert that into a percentage?  

**Please include as much software version information as possible. This ensures that other users and CommandFusion staff can provide a helpful answer as quickly as possible.** - Please Delete this line BEFORE posting.

[Barry Gordon]

Mathematically it's is trivial and would be so in Javascript. Take whatever value you have and divide it by the maximum value it can achieve. That produces a fraction ranging from 0 to 1. Multiply that by 100 and you have the percentage you want.

Sent from my iPad

On Feb 3, 2014, at 5:23 PM, Eric Williams <ewilli...@gmail.com> wrote:

I'm using the Crestron Mobile V3.4 with a particular gui.  I have a 16bit analog value coming in (volume gauge). I would like this to be displayed as a percentage 0-100% on a serial join.  I already have a function triggering when the join changes that uses parseInt to return a value.  Is there a easy way to simply convert that into a percentage?  

**Please include as much software version information as possible. This ensures that other users and CommandFusion staff can provide a helpful answer as quickly as possible.** - Please Delete this line BEFORE posting.

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[Eric Williams]

Damn, that was way too obvious, I think I've been working to much...

 

thanks,

[Barry Gordon]

After you have done 20 or so sliders it kind of becomes ingrained.

Sent from my iPad

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[Kol Johnson]

You can do the translation in Simpl (divmod) then you will only be sending 100 possible values to CF instead of 65536.

[Barry Gordon]

It depends on what you want to do with the value once you get it.  If you want to use the value to control a slider then you need to scale it to be 0-65535. If you want to show it as a percentage you need it to be scaled 0-100.

 

I do both for my lighting system. My lighting system returns 0-100 so I only need to scale it for a slider.  (divide by 100, multiply by 65535 or just multiply by 655.35)

 

The volume return from my A/V system is more complex.  It returns a value from -80 to +20. In that case two things need to be done. First the origin needs to be reset by adding 80 to the returned value producing a value in the range 0-100.  The value can then be divided by 100 to produce a fractional value in the range 0-1.  In Javascript all arithmetic is handles internally in floating point so the system is more accurate than needed for the display of volumes and we need not worry about rounding errors.