commit 0b4382f41581ac02363958a98558977ad801fdab
Author: Mikkeli <mikkeli@novoyuuparosk.org>
Date:   Tue Aug 4 13:15:00 2026 +0800

    initial commit

diff --git a/pcan-setup.md b/pcan-setup.md
new file mode 100644
index 0000000..6caaf31
--- /dev/null
+++ b/pcan-setup.md
@@ -0,0 +1,132 @@
+# PCAN-USB Adapter Setup on Jetson Orin Nano
+
+## Hardware
+
+- **Board:** NVIDIA Jetson Orin Nano Engineering Reference Developer Kit Super
+- **Hostname:** mikkeli-orin-nano-2
+- **OS:** Ubuntu 22.04.5 LTS (aarch64)
+- **Kernel:** 5.15.148-tegra (L4T 36.4.4, JetPack r36.4)
+- **Adapter:** PEAK-System PCAN-USB (ID `0c72:000c`)
+
+## Onboard CAN
+
+The Jetson Orin Nano has a built-in CAN controller:
+
+- **Interface:** `can0`
+- **Controller:** MTTCan (`c310000.mttcan`) — SoC peripheral at memory address `0xc310000`
+- **Driver:** `mttcan` (built into NVIDIA Tegra kernel)
+- **Module:** `can_dev`
+- **Clock:** 50 MHz
+- **Status:** Always present, currently DOWN
+
+## USB CAN Adapter — Initial Detection
+
+### Problem
+
+The PCAN-USB adapter was physically connected and detected by the USB subsystem:
+
+```
+Bus 001 Device 005: ID 0c72:000c PEAK System PCAN-USB
+```
+
+But no CAN interface appeared. The mainline kernel driver `peak_usb` (which supports this device since kernel v3.4) was **not compiled into this NVIDIA Tegra kernel**.
+
+### Investigation
+
+1. Checked for the `peak_usb` module — not present
+2. Checked kernel config (`/boot/config-$(uname -r)`) — not available (NVIDIA kernel)
+3. Checked for kernel headers — none matched the `5.15.148-tegra` kernel
+4. The NVIDIA Tegra kernel from JetPack r36.4 (`repo.download.nvidia.com/jetson/t234`) uses a custom versioning scheme and does not include PEAK's mainline drivers
+
+## Solution — Build PEAK's Proprietary Driver
+
+### Why PEAK's driver instead of mainline?
+
+PEAK's mainline `peak_usb` driver would be the preferred approach (SocketCAN netdev, auto-loading, no rebuild needed on kernel updates). However, the NVIDIA Tegra kernel does not include it. PEAK's proprietary driver package can be built against any kernel that has headers available.
+
+### Step 1: Download PEAK Linux Driver Package
+
+```bash
+curl -L "https://www.peak-system.com/quick/PCAN-Linux-Driver" -o /tmp/pcan-driver.tar.gz
+cd /tmp && tar -xzf pcan-driver.tar.gz
+# Extracts to: /tmp/peak-linux-driver-9.2.0/
+```
+
+### Step 2: Build with SocketCAN (netdev) Support
+
+The PEAK driver defaults to **chardev** mode (character devices like `/dev/pcanusb32`). For standard SocketCAN tools (`candump`, `ip link`, etc.), we need **netdev** mode:
+
+```bash
+cd /tmp/peak-linux-driver-9.2.0/driver
+sudo make clean
+sudo make NET=NETDEV_SUPPORT all
+```
+
+Key output confirming netdev build:
+```
+CC [M]  /tmp/peak-linux-driver-9.2.0/driver/src/pcan_netdev.o
+LD [M]  /tmp/peak-linux-driver-9.2.0/driver/pcan.ko
+```
+
+### Step 3: Install the Module
+
+```bash
+cd /tmp/peak-linux-driver-9.2.0/driver
+sudo cp pcan.ko /lib/modules/5.15.148-tegra/misc/pcan.ko
+sudo depmod 5.15.148-tegra
+```
+
+### Step 4: Load the Module
+
+```bash
+sudo modprobe -r pcan 2>/dev/null
+sudo modprobe pcan
+```
+
+### Result
+
+```
+$ ip link show type can
+3: can0: <NOARP,ECHO> mtu 16 qdisc noop state DOWN mode DEFAULT group default qlen 10
+    link/can
+8: can1: <NOARP> mtu 16 qdisc noop state DOWN mode DEFAULT group default qlen 10
+    link/can
+```
+
+- `can0` = onboard MTTCan
+- `can1` = PCAN-USB adapter
+
+### Step 5: Bring Up the Interface
+
+```bash
+sudo ip link set can1 up type can bitrate 500000
+```
+
+### Step 6: Read CAN Traffic
+
+```bash
+sudo candump can1
+```
+
+## Build Environment
+
+- **GCC:** 11.4.0 (Ubuntu 11.4.0-1ubuntu1~22.04.2)
+- **make:** Available
+- **Kernel headers:** Located at `/lib/modules/5.15.148-tegra/build`
+- **Driver version:** PEAK Linux Driver 9.2.0
+
+## Important Notes
+
+1. **Out-of-tree module:** This driver is built from PEAK's source against the running kernel. It will **not survive a kernel update** — you must rebuild after any kernel upgrade.
+
+2. **Netdev vs chardev:** The PEAK driver defaults to chardev mode. For SocketCAN tools, you must build with `NET=NETDEV_SUPPORT`. The chardev mode creates `/dev/pcan*` devices and requires PEAK's proprietary API.
+
+3. **Blacklisting:** The PEAK installer (`make install`) blacklists the mainline `peak_*` drivers in `/etc/modprobe.d/blacklist-peak.conf`. Since the mainline drivers aren't available on this kernel anyway, this is harmless.
+
+4. **Bitrate:** The default CAN bitrate is 500 kbps. Adjust as needed for your car's bus (common values: 500000, 250000, 1000000).
+
+5. **Read-only use:** For reading car CAN traffic without transmitting, you only need to bring the interface up. No special configuration is needed.
+
+## Cleanup
+
+Source files left at `/tmp/peak-linux-driver-9.2.0/` and `/tmp/pcan-driver.tar.gz`. Can be removed after verifying everything works.