mikkeli
5d5653acec
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01DDwfd6Ki8UfG4hK6W5YpJz
99 lines
3.9 KiB
Markdown
99 lines
3.9 KiB
Markdown
---
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type: reference
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---
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# ADB in the car
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**In one line: ADB over TCP on the tablet's USB-Ethernet link to the Orin, reached
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from halogen through one SSH port-forward via the Orin.** TCP mode is armed once
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over a USB cable to halogen, and again after every tablet reboot.
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## Why USB debugging is unavailable in the car
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A USB link has exactly one host and one device. The tablet's single USB-C port can
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be either, decided by the USB-C CC resistors at plug-in:
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| Plugged into | Tablet role | USB debugging |
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|---|---|---|
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| halogen | device | yes: ADB is a USB function the tablet offers as a device |
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| the Orin (via the PD hub) | **host** | no: a host offers no USB functions |
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A data hub does not help: it adds more devices under the same host. The PD hub in
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the car only passes power through, so the tablet charges while it is the host.
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## What the link is
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The Orin runs Jetson's USB device mode (`l4t-usb-device-mode`) and presents itself
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as a USB network adapter, with a DHCP server on it. The tablet's kernel binds it as
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**NCM** and Android brings it up as an ordinary **Ethernet** network:
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```
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tablet 192.168.55.100 ⇄ USB NCM ⇄ Orin 192.168.55.1
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```
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The app reaches `svc-gw` over this network. It requests the network explicitly and
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binds to it, because a network without internet never becomes Android's default
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while WiFi or LTE is up. `adbd` is a system daemon and needs none of that: once
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it listens on TCP, it listens on every interface, this one included.
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## The path from halogen
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halogen is not on `192.168.55.0/24`; the Orin is. halogen reaches the Orin over
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the LAN or the tailnet (the Orin has an LTE uplink), so one SSH local forward
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bridges the gap:
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```
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adb (halogen) → localhost:15555 ═SSH═▶ Orin → 192.168.55.100:5555 → adbd (tablet)
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```
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Authorisation is unchanged: the tablet still checks ADB's RSA key, and halogen's
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key was accepted at the USB pairing. The tablet's port is reachable only from the
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NCM link (and from WiFi, while TCP mode is on and WiFi is up).
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## Steps
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**1. Arm, at the desk** (USB cable to halogen; once per tablet boot):
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```bash
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adb -s 1f1530c87d84 tcpip 5555
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```
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**2. In the car** (tablet on the Orin, app link up):
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```bash
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ssh -N -o ExitOnForwardFailure=yes -o ServerAliveInterval=10 \
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-L 15555:192.168.55.100:5555 mikkeli-orin-nano &
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adb connect localhost:15555
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adb devices # → localhost:15555 device
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flutter run -d localhost:15555 --dart-define=YUKART_GW=ws://192.168.55.1:7700/
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```
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The default gateway address already is `ws://192.168.55.1:7700/`; the define only
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matters if a desk build was installed last.
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**3. Disarm** (optional): `adb usb` returns ADB to USB only. A reboot does the same.
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Local port 15555, not 5555: halogen's adb server scans localhost 5555–5585 for
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emulators, and a tunnel there shows up a second time as `emulator-5554`.
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## When it does not work
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| Symptom | Check |
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|---|---|
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| `connect` refused or times out | From the Orin: `nc -zv 192.168.55.100 5555`. Refused means TCP mode is off: the tablet rebooted; re-arm over USB |
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| No route to `192.168.55.100` from the Orin | The USB link is down: cable, PD hub, or the tablet asleep (see the initial plan, "The USB link, as measured") |
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| `unauthorized` | Accept the prompt on the tablet; the halogen key was revoked or never accepted |
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| `bind: Address already in use` on 15555 | An old tunnel is still running: `pkill -f 15555:192.168.55.100` |
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## Alternatives
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- **adb on the Orin itself.** `adb connect 192.168.55.100:5555` there, no tunnel.
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Needs `adb` installed on the Orin, and `flutter run` stays on halogen anyway.
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- **Wireless debugging** (Android 11+, pairing codes) survives better, but it only
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runs over WiFi, so it does not use this link.
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## Status
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The NCM link and the app over it are verified (2026-10-09). The ADB path above is
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**untested in the car**; HyperOS may need its USB-debugging security options for
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installs over TCP as it did over USB.
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