Mounting the prototype of the 91 cells electronic board game

posted in: Helvetios, Projects | 0

Finally I’ve gathered all the components and mounted the first full prototype of the board game (I already did some test previously to validate the SPI led drivers in First prototype of the electronic board game Helvetios). The component shortage has delayed the mounting by 6 months until I’ve got some critical components, mainly the led driver TLC5947 and the DC/DC regulator TPS561201.

Initially I contacted some pcb companies from China to fully build the prototypes, but the cost of the components at the start of 2022 was way too much. So I ordered only the PCB and the bottom stencil in JLCPCB, and then I gathered the components until have them all so I could build the circuits by myself.

I did the mounting by hand (in the absence of an SMD oven as the I used for the circuits in the LifeLinker), using soldering paste, a hot air soldering station and a lot of patience. To solder the bottom side I used a stencil so it’s were there are more integrated circuits and some with thermal pads like the led driver. This way the solder paste distribution would be much better.

The circuit was designed to be content in size so the first prototypes would be more economical due the pcb price and the necessary acrylic sheets to make the led difusor and the cell separator. This way we could program all the firmware to control the leds and the USB communication. The next designs will follow the concept of row circuits as explained in Helvetios. This way we could make boards with more and bigger cells.

Some pictures of the mounting process:

Helvetios circuits
The circuits as they arrived.
pads detail
The size of the pads for the led drivers is really small.
fixed circuit
Fixed circuit to use the stencil and apply the solder paste.
Components mounted
Components mounted ready to solder with the hot air station.

To start the prototype I used a development board NUCLEO-F103RB, which I already used in First prototype of the electronic board game Helvetios. This time I used the development board to program the circuit, using the connector that allows to program other circuit by using the SWD communication. This way I could connect to the electronic board game and debug the code for the led drivers and the Hall sensors:

Firmware development setup
Firmware development setup

Besides the development board I used a little 8 channel 24MHz logic analyzer. With this device and the software Pulseview from the Open Source project Sigrok is easy to see which signals are generating and check the correct addressing of the led drivers. Also you could decode some protocols as SPI and I2C, and is very useful to determine the refresh speed of the system.

Pulseview software

When testing the code I also tried some led diffusers:

Acrylic Diffuser Opal Ice 3mm
Acrylic Diffuser 33% 2mm

And finally a video showing the cell detection and some color examples:

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