The last few days I built a 8x8 hall sensor matrix. Therefore, I used the hall effect switch "A3144EUA". The rows are connected to a multiplexer which multiplexes a voltage of 5V. the columns are connected to a demultiplexer, offering an input for the arduino. The arduino pin is read via INPUT_PULLUP.
In my tests without multiplexer I had a very nice behavior. At about 3cm distance from the sensor to my magnet the switch toggled. Now that I multiplex them I have to come as close as 1,5cm. This is really bad for my project. I meassured the supply voltage which has dropped to 1.7V in the matrix. Although, I increased the delay to 200ms before each toggle at the multiplexers, I can not get it working with the distance of 3cm.
Why is that? There are no resistors or anything else. Do the multiplexers restrict the voltage?!
The only solution I thought of, would be supplying the voltage directly, not through the multiplexer, and toggle them with transistors connected to the multiplexer instead. What do you think, would that help?