Task notify: Hello goodbye

On Wednesday, I spent some times implementing task notify on the sensor task, until implementing it on the h-bridge task. Then, I realize that it creates many memory errors and was not really useful since the thread should not call the function that change the multiplexer until the I2C communication was finished.

I also find the way to put some values in the esp32 that I used for the test as an I2C slave, and realized that it works with only 7 bits adresses whitout a read/write bit at the beginning, so I changed its adress and it correctely acknowledge to my communication.… Read more

Coding for test

On Thursday and Friday, I spend some times coding the threads of the test PCB. I first debug and check if everything was ok for our thread that will read the state of all the box via the hall effect sensor. I used a logic analyser to check if everything was fine. I checked that the four pins that will be used for the multiplexer will not change until the end of the sending of an I2C message. Then I code a thread that initializes all the H-bridge by putting them at the 0 state.

I also realize that I have not seen a mistake in our scheme.… Read more

Some tests before the prototype: Let’s PCB

A Test PCB

Before making our first device, we aimed at having a smaller one to test some components we do not have time to test: h-bridge, multiplexer, etc.

So, I had to complete a Test PCB that Alexis began. We already have chosen the components, and he chose the step-down converter, which we would use for our circuit.

I spend two days for placing and routing this PCB. We had two constraints: to put our coils at a precise place and the hall sensor just under them and to add the other component where there was still someplace. We choose to try to not add a battery since a phone charger can give us a 5V voltage with 1,5A current.… Read more

Going back and forth the H-Bridge

We need to be able to drive our little magnet marbles and flip them according to a magnetic field direction or the opposite one. To do so current must be able to flow both ways through our self-inductances. Moreover we’re going to need current’s intensity of a much higher value than what is able to flow out of or flow in the GPIO.

One way to do so, is to use a H-Bridge as we can see on this site that we’ve already mentionned in an earlier post.

What’s an H-Bridge

Basically an H-Bridge is a electronic circuit built with drivable switches in a way that allows us to flip the voltage on a load and thus allows us to flip current polarity.… Read more