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First PCB tested

A project log for Open FFBoard

A modular and open source force feedback interface and motor driver for DIY wheels and controllers

Yannick (Gigawipf)Yannick (Gigawipf) 03/28/2019 at 19:323 Comments

Finally the first pcb arrived and is tested to find any errors in the design and see if there are any major issues.

Soldering everything by hand takes some patience but everything works as it should.

A few problems spotted in the first design:

1. Vias under the current shunts are too close to the pads and can be bridged to the resistor while soldering and short out the shunt voltage.

2. Pullups of encoder were connected to 5v instead of 3.3v. Easy to bodge for now and fixed in the next version.

3. 3.5mm terminals might be too small for big motor wires. Maybe add a 5mm footprint and move the caps and buttons.

4. USB footprint from eagle not exactly the correct one for the ports. Drilled holes are in slightly different spots.
Strange as the part numbers were identical and can be fixed by bending the mounting pins of the port inwards but should be changed to the correct one.

Apart from that the driver and processor work correctly. I chose the STM32F411 as the main processor running at 96MHz. 2 LEDs for status messages, one power led and one direct driver flag led for critical errors are present on the board.

And of course the gamepad communication is working with 16 buttons and 8 analog inputs.
The encoder input is correctly scaled to 1080° of rotation and perfectly matches the virtual wheel in project cars.

Discussions

K.C. Lee wrote 05/11/2019 at 22:37 point

You could change to tented vias - i.e. vias covered by solder mask to minimize chance of shorts.
https://www.bhoite.com/2018/01/tented-vias-in-autodesk-eagle-cad/

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Yannick (Gigawipf) wrote 05/12/2019 at 09:02 point

afaik jlcpcb does not allow tented vias yet but might be good to keep in mind later.

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K.C. Lee wrote 05/18/2019 at 10:07 point

First result on google: 
https://easyeda.com/Daisy/Six_Reasons_Why_JLCPCB_is_Our_Best_PCB_Fabrication_Choice-d48120fc417a4b3da4dc550e28f4dbb5

>Vias that I had tented & not-tented are correct. Silk (both sides) is spot on, 45-mil(1.14mm) high 6-mil(0.1524mm) wide text, very good looking. Boards was built in 3 days and shipped in 4 days received them the next day in USA by DHL.

Tented is pretty standard.  Plugged is a different thing.

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