Tony - What’s a good Hall effect type sensor fo...
What’s a good Hall effect type sensor for reading rpm from the flywheel via a magnet? Ideally some analog type that can be powered from the esp32 pinout
9 Replies
Littelfuse 55100-series are good. Using in my ESP to read RPM from flywheel, which have 6 pcs neodymium magnet on it. This gives 10 RPM resolution if detection time 1s.
https://m.littelfuse.com/media?resourcetype=datasheets&itemid=6d69d457-770e-46ba-9998-012c5e0aedd7&filename=littelfuse_hall_effect_sensors_55100_datasheet.pdf
https://www.digikey.fi/en/products/filter/position-proximity-speed-modules-industrial/1065?s=N4IgjCBcoLQCxVAYygMwIYBsDOBTANCAG4B2aWehA9lANrgCcArExALqEAOALlCCAF8hQA
How is it wired? Any resistor to pull up or straight to the header pins?
Hall output is open collector so pull-up to 3v3 and small RC-filtering in series. No need to have opto or any other elements between.
I can share schematics with exact version of Hall sensor and sample code if needed. I can do this beginning of next week when back home. I try to find magnet version too if possible.
RPM sensoring has been up and running last ~4 years with couple ESP HW.
That would be awesome. Im not in any hurry. My Balmar voltage regulator provides tachometer output but when the battery is full it stops working. I want a second one that is always working so I can add an alarm for oil pressure drop when engine is running
@Karl-Erik Gustafsson I bought the same hall effect sensor and would like to fit it to an esp32. I have a HALMET board with built in pull up and pull down resistors for digital input. You mentioned needing a pull up. I am curious about the filter requirement
Today I checked version and it is 55100-3H-02-A
Pull-up, use ~5mA current to calculate R. For 3V3 R=680 Ohm.
RC-filter e.g. 470R and 10nF is fine as switching speed is max 12kHz for the hall.
Awesome. Same sensor as what I bought. @Matti Airas Would I do pulse as + for digital input and + to 3.3 pin, - to ground for the HALMET?
HALMET's internal pullup is very weak, so not really great for that. You could add your own, of course (but only HALMET 1.0.1 have the isolated 3.3V broken out).
Okay I think I have a good circuit now. Thank you!
You could decrease filter C a little bit to reduce Hall swithing time current.