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Old Sep 21, 2008, 11:32 AM
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Joined Dec 2005
47 Posts
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current limitting with just one adc input ??

can this be done ?? Idea`s are welcome ..

The problem is, I have the vref- and vref+ already set and I dont them to get to close to each other as I use adc for controlling the amount of power to the motor and I dont want that conversion to be to sensitive. Also as te titel did allreay mention. I have only one analog or digital input/output pin left
on my pic16F88.

I`m thinkking about using the piece of cable from the battery to the negative connection of the controller as the shunt. So I only need one measuring point as the other point would just be the ground. but I`m concerned about precision.

Well thinking about it, I just need to calculate.. vref- is ground 0 and vref+ is 5 Volt so 5 Volt : 255 = 0,01960784313725490196078431372549 volt precision
lets say I want about 10 amp acurracy than 0,01960784313725490196078431372549 x 10 = 0,1960784313725490196078431372549 Ohms of cabe resistance is what i need ... and it would than be capable of measuring up to 255 x 10 = 2550 Amp. I have no idea if this is possisible .. and also connectors and stuff needs to be the same resistance everytime its reconnected ..

Anny way, anny thoughts, idea`s or experiences are well apreciated.




measuring voltage only at one point.
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Old Sep 21, 2008, 11:39 AM
Dimension Engineering
Akron, Ohio
Joined Jan 2002
1,705 Posts
Current sense amp. I like max4173. Easy as pie.
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