# obu-firmware — setup & flashing notes

## Two toolchains - use a dedicated terminal for each

Since 2026-09-23 this project builds against ESP-IDF **6.0.2** exactly
(`C:\Espressif\frameworks\esp-idf-v6.0.2`): it is the vanetza-idf port (see
NOTES.md), and vanetza-idf's `radio_c5.cmake` refuses any other version because
the raw TX path pokes private Wi-Fi driver structures only validated there. The
previous C firmware used the receiver firmware's IDF **6.1**; the separate
`obu-cam-transmistter` project builds against the global ESP-IDF **5.5.4**.
Exporting two of them in one PowerShell window fails: the second export
inherits the first's `IDF_PYTHON_ENV_PATH` and reports every Python dependency
as unmet. Don't run `install.bat` to "fix" that - open a fresh terminal, or
clear the state with `$env:IDF_PYTHON_ENV_PATH = $null; $env:IDF_PATH = $null`.

The build also needs the colleague's `microbu-esp32c5` tree, which this
repository carries as ordinary files in `microbu-esp32c5/`: vanetza-idf is taken
from its `external/vanetza-idf`. Pass `-DVANETZA_IDF_DIR=<path>` to `idf.py` if
it lives elsewhere. The first build downloads `espressif/esp-boost` into
`managed_components/`.

`microbu-esp32c5/` is a copy, not a submodule: nothing is fetched from or pushed
to the colleague's repository (HAW GitLab, urban-mobility-lab/microbu/
microbu-esp32c5). It was taken at their commit cf4b99f plus our V2X2MAP
signature verification (local commit 428a386; that repository's history is kept
outside this one in `..\microbu-esp32c5-colleague.git`). To take a newer version
of their tree, copy it over this folder, rebuild and test, and commit it here.

## Every new PowerShell session

```powershell
Set-ExecutionPolicy -Scope Process -ExecutionPolicy Bypass
$env:IDF_TOOLS_PATH = "C:\Espressif"
C:\Espressif\frameworks\esp-idf-v6.0.2\export.ps1
idf.py --version    # v6.0.2
```

## Build & flash

Flash over the board's **UART-bridge port** (CH343; COM3 for the production OBU
on the bench), not the native port the phone uses.

```powershell
cd C:\Users\Ashin\AndroidStudioProjects\MicrOBU\obu-firmware
idf.py set-target esp32c5      # only needed once per clean build folder
idf.py build
idf.py -p COM3 -b 921600 flash monitor
```

Swap `COM3` for whatever port the ESP32-C5's bridge enumerates as (Device Manager →
Ports). `monitor` opens the serial console after flashing — `Ctrl+]` to exit.
Use `flash` (bootloader + partition table + app), not `app-flash`, whenever the
partition table may differ from what the board has.

### First flash onto a board with the previous firmware

The partition table changed with the port (NVS 24 KB → 80 KB, app 0x10000 →
0x20000), and the old NVS is full of Wi-Fi settings the previous firmware left
behind. Erase the whole new NVS range once, then do a full flash:

```powershell
python -m esptool --chip esp32c5 -p COM3 -b 921600 erase-region 0x9000 0x15000
idf.py -p COM3 -b 921600 flash
```

Without the erase, the board cannot store the BLE bond and the phone has to pair
on every connection (2026-09-23). After it:

- the boot log shows `0 bonded phone(s) in NVS`, `BLE advertising started as
  'micrOBU-XXXX'` and `station task ready`; the radio stays off until the app
  connects;
- on the first Connect the app provisions the demo credentials once (the card
  says "Provisioning the demo credentials"); they stay in NVS from then on;
- a phone that was paired with the board before must forget `micrOBU-XXXX` in
  Android's Bluetooth settings and pair again (passkey 123456).

Erasing NVS later (e.g. after a partition change) has the same effects.

## Going back to the previous firmware

The previous, unsigned C firmware (frame types 0x01-0x05, CAM over USB only)
can come back two ways. The app detects it and falls back to its protocol.

- **Image:** `firmware-backups/` in the repository root (gitignored, on the lab
  laptop only) holds a full-flash image of the COM3 board as it was before the
  port, with the esptool command in its README.txt. It restores the old
  partition table and NVS too.
- **Source:** commit `7285fa1` is the last one before the port. Check it out in
  a separate worktree and build it with the receiver firmware's IDF 6.1
  (`its-g5-receiver-firmware\esp-idf\export.ps1`). Erase the NVS range as above
  first, then `flash` (full, since the partition table differs); erasing after
  flashing would wipe the start of the old app, which sits at 0x10000.

## If the build fails

- **"includes X.h, provided by Y component(s)... not in the requirements
  list"** — IDF 5.x split the old monolithic `driver` component apart
  (`esp_driver_gpio`, `esp_driver_uart`, etc.). Add the named component to
  `REQUIRES` in `main/CMakeLists.txt` and rebuild. Already fixed once for
  `esp_driver_gpio` + `esp_driver_uart` — if a new header comes up, same fix.
- Otherwise, start clean before re-building:
  ```powershell
  idf.py fullclean
  idf.py build
  ```

## Connecting the phone (ESP32-C5-WIFI6-KIT)

The board has two USB-C ports — use the right one:

- **Native USB-C port** (labeled for JTAG/native USB, up to 12 Mbps) — this
  is where the phone plugs in via USB-OTG. The station link
  (`serial_link.cpp`: station-link messages as frame type 0x10 in the 0xAA55
  framing) runs over the ESP32-C5's native USB Serial/JTAG peripheral on this port, enumerating as a CDC-ACM device under Espressif's
  VID/PID (0x303A/0x1001).
- **UART-bridge port** (labeled for flashing) — this is what you use for
  `idf.py flash monitor` from your PC. Leave the phone unplugged from this
  one; it only carries `idf.py`'s flashing protocol and the ESP_LOG console.

The app recognizes the ESP32-C5's VID/PID via a custom probe table in
`UsbSerialTransport.kt` (the default `usb-serial-for-android` prober doesn't
know Espressif's device IDs). If the phone doesn't detect anything when
plugged into the native port, first confirm with a tool like "USB Device
Info" (or `adb shell dumpsys usb` from a PC) that Android sees a USB device
at all — that isolates a bad/charge-only OTG cable from an app-side issue.

## Bring-up checklist (phone <-> ESP32-C5 link)

Work down this list — each step isolates the layer below it.

1. **Flash and install together.** The app detects the firmware generation by
   its heartbeat and speaks either protocol, but only an app from 2026-09-23 on
   knows the station-link protocol; messages are at most 512 octets on both
   sides.
2. **Does Android see the device at all?** Plug the phone into the **native**
   USB-C port, hit Connect, and read logcat for `UsbSerialTransport`. It logs
   every attached device *and* each device's interfaces. Empty list = cable /
   OTG / wrong port, below the app entirely.
3. **Did the right interface get claimed?** The C5's USB Serial/JTAG is a
   composite device — expect CDC control (class 2) + CDC data (class 10) +
   vendor-specific JTAG (class 255) in that dump. Compare against the `ports=`
   count on the `matched device` line.
4. **Is the link alive?** The firmware sends a STATUS at 1 Hz regardless of
   radio traffic, and the app marks the link ERROR after ~3.5 s of silence.
   Connected-and-staying-connected means device→host actually works. The board
   starts its radio only after the app's STATION_CONFIGURE, so nothing is
   received before Connect.
5. **If it connects but no V2X_RX ever arrives** — suspect DTR. The app now
   asserts DTR/RTS on open (`openDevice()` in `UsbSerialTransport.kt`), because
   `CdcAcmSerialDriver` doesn't do it by default and the ESP32's USB Serial/JTAG
   endpoint may gate TX on the host opening the CDC line. **This is still
   unverified on real hardware** — test it both ways (with the `setDTR(true)`
   call and with it commented out) and record the answer in `serial_link.h`
   next to the VID/PID note, so nobody has to guess again.
6. **Watch the counters, not just "Sent: N".** The CAM Pinger card shows
   consecutive write failures (phone side) and the firmware's tx-failure /
   RX-queue-drop / CRC-error totals from the heartbeat; the connection card
   shows tickets, signed and refused counts. A rising `tx fail` means messages
   reach the ESP32 but the radio refuses them — a radio problem, not a link
   problem. A rising `refused` with signing on usually means no ticket (NVS
   erased: reconnect so the app provisions again).

## Connecting over Bluetooth instead

Settings > Connection > ESP32-C5 > link: Bluetooth, then Connect. The board
advertises as `micrOBU-XXXX` (last two bytes of its BT MAC; `micrOBU-4AFA` on
COM3), but only while nothing uses its native USB port. Android asks to pair
the first time: passkey **123456** (fixed in `simple_ble.cpp`). The bond is kept
on both sides; the board keeps one bond, so pairing a second phone or a PC
replaces the first. Log lines on the console start with `cits_ble:`.

## Notes

- No `git submodule update` needed here — obu-firmware has no pinned
  submodule of its own, unlike its-g5-receiver-firmware.
- Don't use the global "ESP-IDF 5.5 PowerShell" shortcut or the receiver
  firmware's 6.1 checkout — export from `esp-idf-v6.0.2`, the version the
  vanetza-idf radio's undocumented driver internals were verified against.
- The console (ESP_LOG, boot messages, panics) stays on the UART-bridge port.
  Opening it resets the board; do that only while nothing else depends on the
  session.