saltylab-firmware/jetson/docs/pinout.md

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)

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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:

ls /dev/i2c-*
i2cdetect -l

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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

# 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

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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.

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

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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)

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

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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

# 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°

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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)

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

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

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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

# 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

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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

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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

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9. udev Rules

Apply stable device names:

# /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"

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