Build the car device

The in-car unit: 7" touchscreen, offline map, GPS navigation, two-tap hazard reports over LoRa. No soldering; one jumper cap moves.

1. Order the parts

HF vs LF: the dongle comes in HF (850–930 MHz) and LF (410–490 MHz) versions. For the US mesh you want HF. Two dongles make a bench pair — worth ordering a spare.

2. The one hardware step: the USB hub jumper

Out of the box, only ONE of the kit's four USB-A ports works — the factory jumper bypasses the onboard USB hub. You need two ports (GPS + LoRa), so:

1. Find the H3 3-pin header with the yellow jumper cap, near the USB-A stack (next to the FSUSB42UMX chip).
2. Move the cap to the DEVICE side of the header — yes, DEVICE, counterintuitive as that reads when you're enabling more host ports. (Electrically: SEL=L → hub upstream enabled.)
3. Result: three live USB-A ports through the hub. (The single port that worked before goes dead in this position — expected.)

No firmware change needed — the firmware already handles the hub.

3. Configure the LoRa dongle (once, on any computer)

The dongle ships tuned to 868 MHz (channel 18) — the mesh lives at 915 MHz (channel 65). Fix it over the dongle's serial port (115200 baud, every command ends with CRLF):

+++
AT+TXCH=65
AT+RXCH=65
AT+EXIT

Any serial terminal works (screen /dev/cu.usbmodem* 115200, PuTTY, the Waveshare SSCOM tool). You should see OK after each command.

⚠️ Never hold the dongle's KEY button — 2 seconds silently restores factory settings (back to 868 MHz).

4. Install ESP-IDF v5.5

The firmware builds with Espressif's ESP-IDF, version 5.5:

git clone -b v5.5 --recursive https://github.com/espressif/esp-idf.git ~/esp/esp-idf
cd ~/esp/esp-idf && ./install.sh esp32p4

(Full official guide: ESP-IDF Get Started.)

5. Build and flash

Connect the kit's USB-C debug port to your computer, then:

git clone https://github.com/alviso/waycast.git
cd waycast/targets/esp32p4
. ~/esp/esp-idf/export.sh
idf.py set-target esp32p4
idf.py build
idf.py flash

First flash takes a few minutes (it writes the map-tile fallback partition too). This is the only USB flash you'll ever need — the partition table is A/B and every later update arrives over the air — tap the gear (⚙) in the top bar → Check update — with automatic rollback if an update misbehaves.

6. First boot checklist

Insert the microSD, plug GPS + LoRa dongles into the hub ports, power on. You should see:

• the map (grid or demo tiles at first — real tiles come next)
• bottom-left diagnostics: USB GPS: … | LoRa(C): open …
• top-left: GPS acquiring (amber) → GPS live (green) once it sees sky — first fix takes 1–2 minutes outdoors

7. Load offline maps

Easiest: on the device. Tap the gear (⚙) in the top bar → join your Wi-Fi → tap a coverage tier:

Tiles land on the card and stay there. (Map data © OpenStreetMap contributors.)

8. Done — now what?

• Report something (the orange button, two taps). If a town node is in range you'll see ⌂ its name in the status bar, and your report's chip gets a green dot when the town confirms it heard you.
• Build your town a town node — a mesh with memory beats two cars shouting.
• Something weird? Troubleshooting.