mikkeli
787c414c0a
The backup pin doesn't charge, so a rechargeable ML2032 would just drain with a third of the capacity. Adds the expected life (~1.5-2 yr typical), polarity and post-fit test notes, and marks the item low priority since NTP covers almost every online boot. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
78 lines
4.7 KiB
Markdown
78 lines
4.7 KiB
Markdown
---
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type: reference
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---
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# Bill of Materials
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## PEAK-System PCAN-USB
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| Field | Value |
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|-------|-------|
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| **Manufacturer** | PEAK-System Technik GmbH |
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| **Model** | PCAN-USB |
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| **USB ID** | `0c72:000c` |
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| **Purpose** | USB-to-CAN adapter for reading car CAN bus traffic |
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| **Interface** | SocketCAN netdev |
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| **Default bitrate** | 500 kbps |
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| **Driver** | PEAK proprietary driver 9.2.0 (netdev build) — out-of-tree module, must be rebuilt after kernel updates |
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### Notes
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- The mainline kernel driver `peak_usb` is not compiled into the NVIDIA Tegra kernel (JetPack r36.4), so PEAK's proprietary driver is required.
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- Must be built with `NET=NETDEV_SUPPORT` for standard SocketCAN tools (`candump`, `ip link`, etc.).
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- The module lives at `/lib/modules/$(uname -r)/misc/pcan.ko` and is loaded via `modprobe pcan`.
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- Jetson Orin Nano has a built-in CAN controller (exposed by GPIO pins). Kernel `canN` order is not stable, so both are pinned by udev: onboard → `can_onboard`, PCAN-USB → `can_pcan` ([device naming](impl/reports/DEVICE-NAMING.md)).
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## Waveshare SIM7600G-H-M.2
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[hat](https://www.waveshare.com/wiki/SIM7600G-H-M2_4G_HAT) [module](https://www.waveshare.com/wiki/SIM7600G-H-M.2)
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| Field | Value |
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|-------|-------|
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| **Manufacturer** | Waveshare (SIMCom SIM7600G-H-M.2 module) |
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| **Form factor** | M.2 B KEY |
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| **Purpose** | LTE Cat 4 cellular + multi-constellation GNSS (GPS, Beidou, GLONASS, GALILEO, QZSS) |
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| **Interface** | USB (ttyUSB* for AT commands/NMEA, QMI `cdc-wdm0` + `wwan0` for data) |
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| **Power** | 3V – 4.2V (board rail) |
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| **Antennas** | 3× IPEX (LTE main + LTE diversity + GNSS) |
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| **Max data rate** | 150 Mbps DL / 50 Mbps UL (LTE Cat 4) |
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### Required software
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| Package | Purpose |
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|---------|---------|
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| `gpsd` | Decode NMEA from the GNSS ttyUSB port |
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| `ModemManager` + `NetworkManager` | Manage the modem and the LTE data connection (QMI) |
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| `qmi_wwan` + `cdc-wdm` kernel modules | Not in the Tegra kernel; built out of tree in `~/infra/qmi_wwan/` |
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| `minicom` (or `picocom`) | AT command terminal for module configuration |
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### Notes
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- The module presents multiple USB serial ports (`/dev/ttyUSB0`–`/dev/ttyUSB4`) — ttyUSB2/3 for AT commands, ttyUSB1 for NMEA GPS data (symlinked as `/dev/sim7600-gps`).
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- Default USB composition (PID 9001) is used with QMI; no PID switch needed. PPP dial-up does not work with the povo SIM (network detaches).
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- Setup details: [SIM7600 setup report](impl/reports/SIM7600-SETUP.md).
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- M.2 B KEY is **not** mechanically compatible with Mini-PCIe.
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- Supply voltage should be ~4.0 V for reliable operation.
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- DO NOT hot-plug while powered.
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## RTC backup battery
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**Status: optional, low priority.** Battery choice settled (CR2032); footprint/R560 still to verify against NVIDIA's schematic.
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| Field | Value |
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|-------|-------|
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| **Purpose** | Keep the RTC (`rtc0`, `nvvrs-pseq-rtc`) running while the board is unpowered, so the clock is correct at boot without network or GPS |
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| **Carrier board** | P3768 (Orin Nano Developer Kit): pads present, **connector not populated** (needs soldering) |
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| **Connector (per NVIDIA docs, as quoted on the forum)** | Wieson AC2651-0011-003-HH, 2-pin, 1.25 mm pitch. A community-used substitute is Molex 53398-0271 header + 51021-0200 housing |
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| **Battery** | **CR2032** (primary 3 V lithium) in a holder with leads. **Not ML2032 or other rechargeables:** the module datasheet says the backup pin (PMIC_BBAT) does not support charging, so a rechargeable just drains, and it has ~⅓ of the capacity |
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| **Expected life** | RTC draws 12–50 µA while unpowered (~15 µA measured on the forum) → CR2032 (~220 mAh) lasts ~1.5–2 years typical, ~6 months worst case. Drains only while the board has no power |
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| **Extra parts** | Forum reports also populating R560 (0.56 Ω, e.g. Panasonic ERJ2BQFR56X); confirm in the P3768 schematic |
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### Notes
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- Without it the clock boots at a stale date (seen 2026-10-08: June 4) until NTP syncs. See the [time sync report](impl/reports/TIME-SYNC.md).
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- Forum sources: [RTC battery on Orin Nano DevKit](https://forums.developer.nvidia.com/t/rtc-battery-on-jetson-orin-nano-developer-kit/296732), [How to add RTC battery](https://forums.developer.nvidia.com/t/how-to-add-rtc-battery-in-jetson-orin-nano/255792).
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- A reported side effect: the battery lead and socket make the case cover sit unevenly.
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- Polarity: one forum post says the positive pad is marked with a white triangle. Confirm with a meter before connecting.
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- Test after fitting: power off fully, wait a few minutes, boot with no network, and check `cat /sys/class/rtc/rtc0/date` (should be today, not a reset date).
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- Low priority: online almost always means NTP within a minute; the gap only matters for offline drives (see the [time sync report](impl/reports/TIME-SYNC.md)).
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