On Friday, I work on reducing the final PCB from 16×16 to 14×14. I have discovered two new things: to delete some route, you can use the tool “add partially selected nets”. You will gain some time until you realise that you delete all the GND and VCC nets… By chance, after spending one-hour routing again theses nets, thinking that you would have gained more time by going back in your git, you can use the command fanout that will route again these nets easily. So, the PCB is almost finished, I just need to adjust the board outline and we can concentrate on the code and the test PCB that may arrive one day.… Read more

Cutting and changing things

On Thursday, I launched the cutting of three planks with the laser cutter. We finally have to change the size of the box. With the coronavirus, we cannot ask for a 510x510mm PCB, so we choose to make a 450x450mm PCB and a 14×14 box.

I also ask for many estimates for cutting a Plexiglas plank and we should finally cut in the same way this plank since the price will quadruple.

Finally, I change the upper part of our 4×4 box too.

Now, I will reduce the PCB

Add some art and useful things

Still waiting for our PCB, I found a lot of little things to do to use my time. Adding some art around our hole, a temporary code for the hall effect sensor, that I cannot know yet if there are bugs or not in it. For this, I take some time at naming the pins in STM32CubeMX because it will be easier then.

I tried 5 different things, and we choose the one on the left finally. The SVG came from Stitches Vectors by Vecteezy

I also add a LED for the big PCB, since it will be useful when coding (we forgot to put one in the previous PCB).… Read more

Be prepared for the big one

While waiting for the test PCB, I have to find something to do. Our laser cutter is only 30cm large for 610cm long, so I find a way to cut our wooden plank it in three ways. I hope that there will be no need to add something, but if the plank bend, we will have to put some wedge in the middle of the plastic plank.

I also have to unbend the wood. We ship a 3m plank that came wound, so I make something like this

I also cut a plastic plank for our test box

And made a better scheme with CorelDraw for those who want to make the same device

At last, I take a look at Ilan code for the beginning of a thread that will check the state of all the box.

Become the sender !

As I wrote in my previous posts, the ESP, the STM and the server were working together to receive images or animations depending of what the user wants. Now it’s time for the STM to become the sender.

The objective:

We want the devices to be able to received images from the server but we also want to establish a connection between Touchs to send images from one to the other. On top of that at the end we want to have a communication between both devices in both ways. But as you may know chi va piano va sano. So first things firts, we implemented the emitting part for the first device.… Read more

PCB: Last step (until we found an error)

On Wednesday, I finished the PCB. I used one trick that found Alexis on our test PCB. We have two VCC, one for the coils and the other for all the other components. So, I create a two-parts plan. The VCC is in green and the VCC_COIL is in yellow.

I also have to route all the components. I found a way to make the routing easier, by enforcing a simple rule. When the route is horizontal, it must be on the top face, and when it is vertical, it must be on the bottom face. I also have to change the pins of the multiplexers in order to route them easily.… Read more

PCB: step 2

On Monday, I routed the 4×4 PCB I placed on Friday. I choose to put one multiplexer at the top of this cell and another one at the right. So the SDA lines (which come from the STM32, not from the multiplexer) will come from the left and the bottom. I also changed the scheme by removing a pull-up I put between the main multiplexer and the other multiplexers.

I try to use some shortcuts I found such as one that swaps the pins, but after reading the manual, I found that without a change in the part editor, I cannot use it, so I finally change the pins in the scheme

Now, I will copy 16 times this cell and continue routing with the other components

PCB: step by step

On Friday, I continued to place components. I spent some time to put the 4×4 coils precisely (in the same way as for the test PCB. I found some keyboard shortcuts that help me to do this quickly, but of course, I found the best shortcuts on Monday, when most of the work was done. I take a look at Alexis’ work he made on our test PCB and found some toolbars that will be very useful for me.

Now, I will try to place the multiplexer and to route it. Then I will copy this 4×4 grid sixteen times to finish the PCB until placing and routing the unique components.

Ready for a test of PCB?

On Thursday, I went to Telecom for the first time of the week. I took advantage of this journey to print the prototype of our box for the test PCB. But I lack plastic plank for the middle part (in green in other photos), so we need to wait for a week to have it. However, we will have it on time because we won’t have the PCB before.

In the afternoon, I began the final PCB. We found before a component for charging the battery on a USB cable (the LTC4088), that I put in the schemes.

After some hours on it, I finally find how to import a DXF file of our PCB.… Read more