We previously tested a Hall effect sensor that, was working, but which gave us a voltage from which we could get the marble’s side. The issue with this is that in the final box, with all the marbles and the coils, we could have had strong pertubations that could alter the data. To avoid this issue we decided to use a sensor that would send the data through a communication protocol that could resist. We chose the TLE493DW2B6A0HTSA1 Infineon Technologies. This sensor sends its data through the I2C protocol so it should resist to our perturbations.
Let’s connect it !
This sensor has 6 pins, 3 have to be connected to GND, one to Vcc and the other two are for SDA and SCL, the two signals from the I2C protocol. The two protocol’s signals are pulled up through a 1.2kΩ and we also added a decoupling capacitor of 100nF.
The internal configuration :
This sensor has many possibles settings.
First of all it can send an interrupt signal on the SCL pin when it has a valid measurement. We chose not to use it because on the final design, all the sensor will be accessed through a multiplexer on the SCL pin. On top of that, the measurement takes less then 1ms, and we won’t need to access that often to the data.
The sensor can also measure the temperature to correct the value of the magnetic field. Yet we don’t need extremely precise value (we just need the orientation) so we didn’t activate this either.
Now let’s use it :
We connected the sensor to our test board. The sensor gives value, centered over the 0 and through the three axis. We will only use the z axis as the sensor will be placed directly below the marble. This also means we only need to test the sign of the data to get the orientation of the field. Yet we chose to fix two bounds so just like with the other sensor we have a middle area that will correspond to a marble not being completly turned.
In order to have something more visual for this post, I chose to use two leds. When the field is greater then 0, a blue led (on the right side of the board) is turned on, otherwise a yellow led (on the left side of the board) will.
Finally we also wanted to test the sensor when there are more then one marble. So we want we a 3×3 configuration with the sensor being below the marble of the middle.
We see that if I turn the marble above the sensor it does detect it and when I turn an other one it does not.