duinotech hall effect sensor on Yun

Hi All,
I am doing a bit of research into Hall Effect sensors and how I could use it to measure the rotation of a wheel with a magnet at a certain point.
Initially I purchased a duintoech hall effect sensor from Jaycar - http://www.jaycar.com.au/Kits%2C-Science-%26-Learning/Science-Lab-Equipment/Specialty-Equipment/Arduino-Compatible-Hall-Effect-Sensor-Module/p/XC4434 - but there is no wiring diagram for it. I am assuming that the s near the connector on the right indicates this is the sensor, with positive being the left connector and gnd being the middle.
It’s specs are:
Output range: on at 30gauss and off at 10.
voltage 4.5 to 28vdc
Output type is schmitt trigger
The code I am using is fairly straight forward I think:

#include <Console.h>
   int raw = 0;
void setup()
  // turn on LED to signal the start of the calibration period:
  pinMode(13, OUTPUT);
  digitalWrite(13, HIGH);


void DoMeasurement()
  // measure magnetic field
  int raw = analogRead(A0);   // Range : 0..1024


void loop()
  digitalWrite(13, HIGH);

  digitalWrite(13, LOW);


This produced data in the console like below regardless of the position of the magnet or the polarity.


This seemed like it would be easy to connect up - sold as Arduino compatible - most of the research I have seen includes the use of the 10k resistor - which I have attempted in a previous incarnation but again to no avail.
Any suggestions would be welcome.


Perhaps it wasn’t too wise to buy a module when there is no datasheet, or even good pin labelling by the look of it.

Having said that, rather than just ‘assume’ what the connections are, why not take note of the part number on the Hall-effect sensor and go looking for it’s datasheet? The connections on the board should be easy to trace. In the pics they look like the pins directly correspond with the sensor’s pins.

Edit: A quick search tells me that it possibly uses a US1881 Hall-effect sensor. If so, and if the module pins connect straight to the sensor pins, then you have the connections wrong. The left-hand pin of the sensor is Vdd, the centre pin is the output and the right-hand pin is GND. (These are the sensor pins, not definitely the module pins.) You’ll need to check that.
It’s an open-drain output, but the pullup resistor is probably one of those on the module.

If it is a US1881 sensor, this is it’s datasheet:- US1881
And more info here:- Arduino Hall Effect Sensor Tutorial
And finally, it’s a digital output, not analogue, so get rid of the analogRead() and use digitalRead().
Also, it’s latching.

Again, all of this is assuming it is a US1881. Let us know if it isn’t.

I’d better add, if it’s a common UGN3503, your connections are correct, but someting weird is going on since you’re not getting an analogue voltage from it.

Thanks for the advise oldsteve. I thought there would have been diagram on the back of it or at least on the website. Not to worry - the advise to look at the part number on the actual sensor was sound. It was very tiny and my eyes are not what they used to be but the part number is 44E 938 - I had to get the hubble telescope re-tasked to zoom into the fine print ( kidding of course). Further searches indicate that 44E 938 translates into an A3144 sensor. For which diagrams are readily available. However, it is not that simple, in the wiring from the sensor to the connector pins they are all over the shop. The ammeter proved invaluable to ascertain which sensor pin mapped to which connector. The sensor connection is the one next to the S. The power connection is the centre connection and the grnd is on the left.
This will be helpful for anyone else that uses one of these hall effect sensors.

All in All a good little exercise - thanks for the help again.


I know it's a bit late but have you seen this?