DIY — custom PCB build

Build the production hardware from scratch. Everything you need — schematic, PCB layout, BOM, firmware source — is in the bimmerz-box repo under MIT.

Looking for the easier path?

This page is the from-scratch build (fab your own PCB, source every part, reflow SMD). If you'd rather wire up dev modules with jumper cables — no PCB fab, no SMD reflow — see DIY from modules.

What you'll need

Tools

• Soldering iron with a fine tip (T12-K or similar)
• Solder paste + a hot-air rework station OR a reflow oven
• Tweezers (curved + straight)
• A multimeter
• USB-C cable
• A USB-Serial cable OR Espressif debug probe (only if you don't trust USB-JTAG flashing on the first boot)

Files (from the repo)

• hardware/BimmerzBox.kicad_sch — schematic
• hardware/BimmerzBox.kicad_pcb — PCB layout
• hardware/BimmerzBox.kicad_pro — KiCad project
• BOM + interactive position file: generate from KiCad (File → Fabrication Outputs)

Parts

Part	Qty	Note
Waveshare ESP32-P4-Module	1	the SoM (MCU + PSRAM + flash + antenna)
TJA1051T/3 (SO8)	2	CAN transceivers
L9637D (SO8)	1	K-line transceiver — VCC on 3.3 V, no level shifter
TH3122 (SO8)	1	IBus transceiver (optional, only if you want IBus)
74LVC1T45 (SOT-23-6)	1	level shifter for the IBus 5 V ↔ 3.3 V path (the K-line doesn't need one)
microSD socket	1	push-push, FAT32
USB-C receptacle	1	data + power
16-pin OBD-II socket	1	board-mount or pigtail (your call)
LM2596 (or MP1584) buck converter	1	12 V → 3.3 V; pick one rated >500 mA
Passives (0805 / 0603 R + C)	~40	exact list in the KiCad BOM
Status LEDs (0805)	4	power / WiFi / comm / fault

Order PCBs from JLCPCB / PCBWay / Eurocircuits using the gerbers. For one-off builds, 4-layer 1.6 mm, 1 oz copper is plenty.

Build steps

1. Reflow the board

Solder paste → place parts → reflow. The Waveshare module's castellated pads are the trickiest — make sure each pad has paste and tack the corners first.

Inspect with a loupe before powering on. Look for solder bridges under the QFN and on the SO8 leads.

2. Smoke test

Apply 12 V (current-limited to 200 mA on the bench supply). Should draw ~80 mA at idle.

• Probe TP_3V3 — expect 3.30 V ± 5 %.
• Power LED should light.

If it draws more, kill it and re-inspect. Most likely a short under the buck converter or a reversed cap.

3. Flash firmware

Plug in USB-C. The Waveshare module exposes USB-JTAG by default on GPIO 24/25 — the dongle appears as /dev/cu.usbmodemXXXX (macOS / Linux) or a COM port (Windows).

git clone https://github.com/emdzej/bimmerz-box
cd bimmerz-box/firmware
. $IDF_PATH/export.sh
idf.py set-target esp32p4
idf.py -DBOARD_VARIANT=dongle build
idf.py -p /dev/cu.usbmodemXXXX flash monitor

Should boot in 5 seconds. Look for:

I (3835) ediabasx_platform: K-line transport registered with VM
I (3850) jsonrpc: WS endpoint up at /rpc/ediabasx
I (3835) wifi_ap: AP up on SSID "BimmerzBox"

4. Load the SD card

Format a 4–32 GB microSD as FAT32 and copy:

/web/dashboard/         — the hub SPA (from bimmerz-box/dashboard/dist)
/web/ediabasx/          — EDIABASX SPA (from ediabasx repo)
/web/inpax/             — INPAX SPA (from inpax repo)
/web/ncsx/, /web/nfsx/, /web/tunex/  (optional)
/data/                  — every BMW data file the apps you've
                          installed expect to find. EDIABAS DATEN
                          disk under /data/ediabas/, NCS-Expert
                          profiles + manifests under /data/ncs/,
                          INPA scripts under /data/inpa/, and any
                          per-tool support files documented in each
                          app's repo.

Insert it. Reboot. Connect to the AP, follow the quick start.

Customising

The PCB design is open — fork, add an L-line driver if you need it for older ECUs, swap to a smaller buck, add a battery for portable use. The firmware reads the pin map from firmware/components/board/include/boards/dongle.h; change those defines for any GPIO reassignment.

Source

• Schematic + PCB: hardware/
• Firmware: firmware/
• Dashboard SPA: dashboard/

License: MIT.