# Jetson Orin Nano Super — GPIO / I2C / UART / CSI Pinout Reference
## Self-Balancing Robot: STM32F722 Bridge + RealSense D435i + RPLIDAR A1M8 + 4× IMX219

Last updated: 2026-02-28
JetPack version: 6.x (L4T R36.x / Ubuntu 22.04)

---

## 40-Pin Header Overview

The Jetson Orin Nano Super 40-pin header is physically compatible with Raspberry Pi HATs.
Pin numbering follows **physical board pin** (1–40).

```
 3.3V  [ 1] [ 2] 5V
SDA1  [ 3] [ 4] 5V         ← I2C SDA (i2c-7 on Orin Nano)
SCL1  [ 5] [ 6] GND        ← I2C SCL (i2c-7 on Orin Nano)
 GPIO [ 7] [ 8] TXD0       ← UART TX (ttyTHS0)
  GND [ 9] [10] RXD0       ← UART RX (ttyTHS0)
 GPIO [11] [12] GPIO
 GPIO [13] [14] GND
 GPIO [15] [16] GPIO
 3.3V [17] [18] GPIO
 MOSI [19] [20] GND        ← SPI1 MOSI
 MISO [21] [22] GPIO       ← SPI1 MISO
 SCLK [23] [24] CE0        ← SPI1 CLK / CS0
  GND [25] [26] CE1        ← SPI1 CS1
 ID_SD[27] [28] ID_SC     ← I2C ID EEPROM (reserved)
 GPIO [29] [30] GND
 GPIO [31] [32] GPIO
 GPIO [33] [34] GND
 GPIO [35] [36] GPIO
 GPIO [37] [38] GPIO
  GND [39] [40] GPIO
```

**Note on Orin Nano I2C bus numbering:** The 40-pin header I2C pins (3/5) map to
`/dev/i2c-7` on Orin Nano (not i2c-1 as on the older Nano). Verify with:
```bash
ls /dev/i2c-*
i2cdetect -l
```

---

## 1. STM32F722 Bridge (USB CDC — Primary)

The STM32 acts as a real-time motor + IMU controller. Communication is via **USB CDC serial**.

### USB CDC Connection
| Connection | Detail |
|-----------|--------|
| Interface | USB Micro-B on STM32 dev board → USB-A on Jetson |
| Device node | `/dev/ttyACM0` → symlink `/dev/stm32-bridge` (via udev) |
| Baud rate | 921600 (configured in STM32 firmware) |
| Protocol | JSON telemetry RX + ASCII command TX (see bridge docs) |
| Power | Powered via robot 5V bus (data-only via USB) |

### Hardware UART (Fallback — 40-pin header)
| Jetson Pin | Signal | STM32 Pin | Notes |
|-----------|--------|-----------|-------|
| Pin 8 (TXD0) | TX → | PA10 (UART1 RX) | Cross-connect TX→RX |
| Pin 10 (RXD0) | RX ← | PA9 (UART1 TX) | Cross-connect RX→TX |
| Pin 6 (GND) | GND | GND | Common ground **required** |

**Jetson device node:** `/dev/ttyTHS0`
**Baud rate:** 921600, 8N1
**Voltage level:** 3.3V — both Jetson Orin and STM32F722 are 3.3V GPIO

```bash
# Verify UART
ls /dev/ttyTHS0
sudo usermod -aG dialout $USER
# Quick test
picocom -b 921600 /dev/ttyTHS0
```

**ROS2 topics (STM32 bridge node):**
| ROS2 Topic | Direction | Content |
|-----------|-----------|---------
| `/saltybot/imu` | STM32→Jetson | IMU data (accel, gyro) at 50Hz |
| `/saltybot/balance_state` | STM32→Jetson | Motor cmd, pitch, state |
| `/cmd_vel` | Jetson→STM32 | Velocity commands → `C<spd>,<str>\n` |
| `/saltybot/estop` | Jetson→STM32 | Emergency stop |

---

## 2. RealSense D435i (USB 3.1)

### Connection
| Parameter | Value |
|-----------|-------|
| Interface | USB 3.1 Gen 1 (USB-A on Jetson — use blue port) |
| Device node | `/dev/bus/usb/...` (udev-managed) |
| USB PID:VID | `0x8086:0x0b3a` (D435i) |
| Power draw | ~1.5W active, 3.5W peak during init |
| Cable | USB 3.1 — use **short cable ≤1m** for stability |

**Note:** Orin Nano Developer Kit has **2× USB-A + 1× USB-C**. Use USB-A (blue = USB 3.1) for D435i.

```bash
lsusb | grep Intel
# Expected: Bus 002 Device 003: ID 8086:0b3a Intel Corp. Intel RealSense D435i
```

**ROS2 topics:**
| Topic | Type | Rate |
|-------|------|------|
| `/camera/color/image_raw` | `sensor_msgs/Image` | 30Hz |
| `/camera/depth/image_rect_raw` | `sensor_msgs/Image` | 30Hz |
| `/camera/aligned_depth_to_color/image_raw` | `sensor_msgs/Image` | 30Hz |
| `/camera/imu` | `sensor_msgs/Imu` | 400Hz |

---

## 3. RPLIDAR A1M8 (UART via USB adapter)

### Connection
| Parameter | Value |
|-----------|-------|
| Interface | USB Micro-B (via included CP2102 USB-UART adapter) |
| Device node | `/dev/ttyUSB0` → symlink `/dev/rplidar` (via udev) |
| Baud rate | 115200 |
| Power draw | ~2.6W motor on, 0.4W idle |
| Motor control | DTR line (handled by rplidar_ros driver) |

```bash
ls /dev/rplidar      # should exist after udev rule applied
ros2 launch rplidar_ros rplidar_a1_launch.py serial_port:=/dev/rplidar
```

**ROS2 topics:**
| Topic | Type | Rate |
|-------|------|------|
| `/scan` | `sensor_msgs/LaserScan` | 10Hz |

---

## 4. 4× IMX219 CSI Cameras (MIPI CSI-2)

The IMX219 (Sony 8MP) cameras connect via MIPI CSI-2 FFC cables to the Jetson Orin Nano.

### CSI Connector Layout (Orin Nano Developer Kit)

The Orin Nano Developer Kit has two MIPI CSI-2 connectors:
- **CSI-A (J5):** 15-pin FFC — connects to ArduCam adapter A
- **CSI-B (J8):** 15-pin FFC — connects to ArduCam adapter B

Each ArduCam multi-camera adapter multiplexes 2× IMX219 cameras onto one CSI lane.

### ArduCam Multi-Camera Adapter Wiring
| Adapter | Cameras | CSI Connector | V4L2 Devices |
|---------|---------|---------------|--------------|
| Adapter A (CSI-A) | front + left | J5 | `/dev/video0`, `/dev/video2` |
| Adapter B (CSI-B) | rear + right | J8 | `/dev/video4`, `/dev/video6` |

### IMX219 15-pin FFC Pinout (each camera module)
| Pin | Signal | Notes |
|-----|--------|-------|
| 1 | GND | |
| 2 | CSI D0- | MIPI data lane 0 negative |
| 3 | CSI D0+ | MIPI data lane 0 positive |
| 4 | GND | |
| 5 | CSI D1- | MIPI data lane 1 negative |
| 6 | CSI D1+ | MIPI data lane 1 positive |
| 7 | GND | |
| 8 | CSI CLK- | MIPI clock negative |
| 9 | CSI CLK+ | MIPI clock positive |
| 10 | GND | |
| 11 | CAM_GPIO | Camera enable (active high) |
| 12 | CAM_CLK | I2C / control clock |
| 13 | CAM_SDA | I2C data |
| 14 | GND | |
| 15 | 3.3V | Power |

### V4L2 Device Nodes
```bash
# List all video devices
v4l2-ctl --list-devices

# Expected output:
# vi-output, imx219 2-0010 (platform:tegra-capture-vi:0):
#         /dev/video0
# vi-output, imx219 2-0010 (platform:tegra-capture-vi:1):
#         /dev/video2
# vi-output, imx219 4-0010 (platform:tegra-capture-vi:2):
#         /dev/video4
# vi-output, imx219 4-0010 (platform:tegra-capture-vi:3):
#         /dev/video6

# Capture test (GStreamer)
gst-launch-1.0 nvarguscamerasrc sensor-id=0 ! \
  'video/x-raw(memory:NVMM),width=640,height=480,framerate=30/1' ! \
  nvvidconv ! xvimagesink

# Capture via V4L2
v4l2-ctl --device=/dev/video0 --stream-mmap --stream-count=1 \
  --set-fmt-video=width=640,height=480,pixelformat=RG10
```

### ROS2 Topics (saltybot_cameras package)
| Topic | Camera | Type | Rate |
|-------|--------|------|------|
| `/camera/front/image_raw` | front (video0) | `sensor_msgs/Image` | 30Hz |
| `/camera/left/image_raw` | left (video2) | `sensor_msgs/Image` | 30Hz |
| `/camera/rear/image_raw` | rear (video4) | `sensor_msgs/Image` | 30Hz |
| `/camera/right/image_raw` | right (video6) | `sensor_msgs/Image` | 30Hz |

### TF Frames
| Camera | Frame ID | Offset from sensor_head_link |
|--------|----------|------------------------------|
| front | `camera_front_link` | x=+0.05m, yaw=0° |
| left | `camera_left_link` | y=+0.05m, yaw=+90° |
| rear | `camera_rear_link` | x=-0.05m, yaw=180° |
| right | `camera_right_link` | y=-0.05m, yaw=-90° |

---

## 5. I2C Bus (i2c-7) — Pin 3 / Pin 5

Available for future peripherals (IMU breakout, OLED display, etc.).

| Parameter | Value |
|-----------|-------|
| Jetson I2C bus | i2c-7 (pins 3 = SDA, 5 = SCL) on Orin Nano |
| Voltage | 3.3V pull-up |
| Max clock | 400kHz (Fast Mode) |

```bash
# Scan i2c-7 bus
i2cdetect -y -r 7
```

**Note:** i2c-0 (pins 27/28) is reserved for EEPROM ID — do not use.

---

## 6. M.2 NVMe Storage

The Orin Nano Developer Kit includes an M.2 Key M slot.

| Parameter | Value |
|-----------|-------|
| Interface | PCIe Gen 3 ×4 |
| Form factor | M.2 2230 / 2242 / 2280 |
| Recommended | 256GB+ NVMe SSD (e.g., WD SN530, Samsung PM991) |
| Mount point | `/mnt/nvme` |

```bash
# Verify NVMe detected
lsblk | grep nvme
nvme list

# Partition + format (one-time setup — see setup-jetson.sh)
sudo parted /dev/nvme0n1 mklabel gpt
sudo parted /dev/nvme0n1 mkpart primary ext4 0% 100%
sudo mkfs.ext4 /dev/nvme0n1p1
sudo mkdir -p /mnt/nvme
```

---

## 7. USB Ports Summary

| Port | Type | Used For |
|------|------|----------|
| USB-A (top, blue) | USB 3.1 Gen 1 | RealSense D435i |
| USB-A (bottom) | USB 2.0 | RPLIDAR (via USB-UART adapter) |
| USB-C | USB 3.1 Gen 1 (+ DP) | STM32 CDC or host flash |
| Micro-USB | Debug/flash | JetPack flash only |

---

## 8. GPIO Summary Table

| Physical Pin | Function | Voltage | Used For |
|-------------|----------|---------|----------|
| 3 | SDA1 | 3.3V | I2C data (i2c-7) |
| 5 | SCL1 | 3.3V | I2C clock (i2c-7) |
| 8 | TXD0 | 3.3V | UART TX → STM32 (fallback) |
| 10 | RXD0 | 3.3V | UART RX ← STM32 (fallback) |
| USB-A ×2 | — | 5V | D435i, RPLIDAR |
| USB-C | — | 5V | STM32 CDC |
| CSI-A (J5) | MIPI CSI-2 | — | Cameras front + left |
| CSI-B (J8) | MIPI CSI-2 | — | Cameras rear + right |
| M.2 Key M | PCIe Gen3 ×4 | — | NVMe SSD |

---

## 9. udev Rules

Apply stable device names:

```bash
# /etc/udev/rules.d/99-saltybot.rules

# RPLIDAR A1M8 (SiliconLabs CP2102)
KERNEL=="ttyUSB*", ATTRS{idVendor}=="10c4", ATTRS{idProduct}=="ea60", \
  SYMLINK+="rplidar", MODE="0666"

# STM32 USB CDC (STMicroelectronics)
KERNEL=="ttyACM*", ATTRS{idVendor}=="0483", ATTRS{idProduct}=="5740", \
  SYMLINK+="stm32-bridge", MODE="0666"

# Intel RealSense D435i
SUBSYSTEM=="usb", ATTRS{idVendor}=="8086", ATTRS{idProduct}=="0b3a", \
  MODE="0666"

# IMX219 CSI cameras (V4L2)
KERNEL=="video[0246]", SUBSYSTEM=="video4linux", MODE="0666"
```

```bash
sudo cp docs/99-saltybot.rules /etc/udev/rules.d/
sudo udevadm control --reload-rules && sudo udevadm trigger
```
