Hall effet sensor on PI
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Hall effet sensor on PI

by mchobby on Sun Nov 04, 2012 7:49 pm

On one hand, the US5881 Hall Effect sensor (sold on AdaFruit WebShop) does not appears to work with 3.3 volts as power supply (cfr tech sheet).
On the other hand, Raspeberry GPIO are not 5v Friendly.

The US5881 usually use a pull-up resistor of 10K to +5v, the US5881 will pull-down the voltage to GND when activated.
See http://mchobby.be/wiki/images/thumb/a/a ... ontage.jpg for schematic.

For Raspberry PI, I would propose to build a resistor bridge with an additional 20K resistor between the Output Pin of US5881 and GND.
By acting like that, Output voltage should be 3.3v (when sensor not activated) or 0v (when the activated sensor pulls down the voltage to GND).

Am I right?

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Re: Hall effet sensor on PI

by adafruit on Tue Nov 06, 2012 11:06 am

connect the pullup to 3.3V

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Re: Hall effet sensor on PI

by jawright on Thu Sep 15, 2016 3:15 pm

I know this is an old thread, but I'm working on a similar project and just want to make sure I am clear on the details.
Should I use a 20K resistor between the US5881 and 3.3V, or 10K resistor (as usual) and an additonal 20K resistor between the sensor and GND?

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Re: Hall effet sensor on PI

by adafruit_support_mike on Fri Sep 16, 2016 5:16 am

Just connect a 10k resistor between the sensor's output and 3.3v. A 20k resistor to GND won't do anything useful.

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