First, the work of some students
We spend a whole week working with just a few responses from Alexis, so we try on our own to find out how to make our architecture. This is what it would look like
We spend a lot of time exploring the best components, as you may have seen it in our previous posts.
We would have to make a lot of FPGA programming for the I/O expander, but we thought it was our unique solution.
We spend some times looking for a sensitive captor touch with only one key and the way to use it because we wanted to use the sensitive captor touch of an ESP32-WROOM-32D.
Then, destroy everything with a single Alexis and build again
We had a meeting with Alexis yesterday. He explained to us that the sensitive captor touch of the ESP32 wouldn’t do the job through the wood. One component to change. Fortunately, we already found a 3-key sensitive captor touch, we just have to make sure it will have enough strength to work through the wood.
Then, we spoke about the price and the length of the device. With 64 I/O expanders, Touch would be too expensive for funding it, that’s why we choose to make only a 16×16 grid of marbles.
The next step was the I/O expander: we cannot use them for our hall effect sensor because they are analogic and not numeric. We thought to change for numeric ones but we will come back to them later
We still need a lot of I/O expander, that’s why we need to find a better architecture for our H-bridge. Alexis first thought to make something similar to the architecture of a digicode. One half H-bridge by line, and one by column. If we want to activate the third coil of the fourth line, we would put VCC on the third half H-bridge and the ground for the fourth half H-bridge.
Finally, taking a look at our H-bridge gave us the best solution. This H-bridge can be controlled by an I2C bus, and we can give each of them a special address, so they can be on the same bus: instead of 32 pins, we just need to use three pins. Two for the I2C bus and one for the address, that we will link to some shift registers to control their address.
Now, are we happy? Not exactly, we still need to find how to control our hall effect sensors. A brief look at component gives us our last solution. We would use some analog multiplexers. So, here is our new architecture.
We are waiting for some coils and Hall effect sensors, and we will begin our tests.