Hall effet sensor on PI

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mchobby
 
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Joined: Tue Jan 24, 2012 3:14 pm

Hall effet sensor on PI

Post by mchobby »

Hi,
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?
Regards,
Dominique

adafruit
 
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Re: Hall effet sensor on PI

Post by adafruit »

connect the pullup to 3.3V

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jawright
 
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Re: Hall effet sensor on PI

Post by jawright »

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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adafruit_support_mike
 
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Re: Hall effet sensor on PI

Post by adafruit_support_mike »

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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