Building your own device

Some keypoints for building your own device. It'll cost around 90€ / $100 and take ~6 hours to assemble start to finish.

Get the parts

PCB

Download the two PCB zip files for the mainboard and the display-subboard. They contain the exported pcb data for the fab. Head over to jlcpcb.com and upload both zip files and order the boards.

If you want to use a different fab, you probably need to get KiCad and export the pcb for your fab manually.

Parts

There are two lists for digikey which contain most of the components. One for the mainboard and one for the display-subboard. The list contains almost every electronic component needed for assembly.

In addition you'll need:

• OLED Display. Get a standard 0.96", 128x64 one with a I²C header and an SSD1306-compatible driver. The I²C-address should be 0x78 or 0x3C, depending on whether they already shifted the address to accommodate the R/W-bit. The pinout should be VCC, GND, SCL, SDA or GND, VCC, SCL, SDA, in this order when looked at from the display side. Pay special attention to the order of VCC and GND, because you'll need to solder the board differently depending on the order. The display can be found on amazon or aliexpress.
• 9x M2 countersink screws, length 15mm together with 9 nuts for said screws
• An acrylic window with dimensions 25x15mm for the display
• A spacer with length 6mm, which fits an M2-screw

Case

The board was designed for a TEKO TEKAL 31.29-case, where the PCB fits nicely into the lowest slot. The PCB should fit into any case designed for eurocards (100x100mm), the height should be at least 45-50mm to accomodate the connectors. It is exceptionally hard to find eurocard-cases though or one with the inner dimensions given. A case that fits this PCB should have a width of around 105-106mm.

Larger cases also work without problem, you can screw the PCB into some standoffs using the four provided holes in the PCB for this purpose. The standoffs can be hot-glued to the case I guess.

Assembly

PCB

Some tips for assembling the PCB:

• Start with the USB-C connector, it is the hardest one. Use flux, a fine tip and little solder and try to go pin by pin, it is doable once you get the hang of it
• The μC is the second hardest thing, but pretty easy in comparision
• After that just go from small to large
• Take care of the dip-switch orientation. On should be where the dot is, otherwise the labels on the PCB will be reversed

Cover

There are exact measurements for the cover in the CAD-folder and an SVG-template for <generic CAD software> if you have access to a CNC-machine. Both templates are from the inside of the case. For the backpanel, [0,0] is the center of the cover. For the frontpanel, [0,0] is at the inner large corner of the pcb right beside the USB-connector. To align the cutout, put the pcb inside the case, put the cover on and with a pen, trace where that corner meets the cover.

If you don't have a CNC, you can also use a drillpress for most things and just print the SVG and use it as a template.

Flashing

To flash the initial image, but the device into DFU-Mode using the jumper. Connect the board to your PC and use the STM32CubeProgrammer to flash the firmware. Then put the jumper back onto its default position (square).