sl-controls
de9a835cc2
Adds saltybot_cellular ROS2 package for the Waveshare SIM7600X 4G HAT
(SIMCom SIM7600A-H) providing GPS telemetry, modem monitoring, and
MQTT relay over cellular for remote operation.
gps_driver_node:
- Opens /dev/ttyUSB2 (NMEA), optionally sends AT+CGPS=1 on /dev/ttyUSB0
- Parses GGA (position) + RMC (velocity) from any NMEA talker (GP/GN/GL/GA)
- Validates NMEA checksum before parsing
- Publishes /gps/fix (NavSatFix, covariance from HDOP × ±2.5m CEP)
- Publishes /gps/vel (TwistStamped, ENU vE/vN from course-over-ground)
- Publishes /diagnostics (fix quality, sat count, HDOP)
cellular_manager_node:
- Polls AT+CSQ, AT+CREG?, AT+COPS? every 5s over /dev/ttyUSB0
- Publishes /cellular/status (DiagnosticArray: rssi, network, connected)
- Publishes /cellular/rssi (Int32, dBm) and /cellular/connected (Bool)
- Auto-reconnect via nmcli or pppd when data link drops
mqtt_bridge_node:
- paho-mqtt client (graceful degradation if not installed)
- ROS2→MQTT QoS 0: /saltybot/imu, /gps/fix, /gps/vel, /uwb/ranges,
/person/target, /cellular/status
- MQTT→ROS2 QoS 1: saltybot/cmd→/saltybot/cmd, saltybot/estop→/saltybot/estop
- Per-topic rate limiting (imu:5Hz, gps:1Hz, person:2Hz) → <<50KB/s budget
- Optional TLS, configurable broker/port/prefix/auth
Deliverables:
saltybot_cellular/gps_driver_node.py — 402 lines
saltybot_cellular/cellular_manager_node.py — 362 lines
saltybot_cellular/mqtt_bridge_node.py — 317 lines
config/cellular_params.yaml — full config documented
launch/cellular.launch.py — all nodes, all params as args
test/test_cellular.py — 60 pytest tests, no ROS2
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Jetson Nano — AI/SLAM Platform Setup
Self-balancing robot: Jetson Nano dev environment for ROS2 Humble + SLAM stack.
Stack
| Component | Version / Part |
|---|---|
| Platform | Jetson Nano 4GB |
| JetPack | 4.6 (L4T R32.6.1, CUDA 10.2) |
| ROS2 | Humble Hawksbill |
| DDS | CycloneDDS |
| SLAM | slam_toolbox |
| Nav | Nav2 |
| Depth camera | Intel RealSense D435i |
| LiDAR | RPLIDAR A1M8 |
| MCU bridge | STM32F722 (USB CDC @ 921600) |
Quick Start
# 1. Host setup (once, on fresh JetPack 4.6)
sudo bash scripts/setup-jetson.sh
# 2. Build Docker image
bash scripts/build-and-run.sh build
# 3. Start full stack
bash scripts/build-and-run.sh up
# 4. Open ROS2 shell
bash scripts/build-and-run.sh shell
Docs
docs/pinout.md— GPIO/I2C/UART pinout for all peripheralsdocs/power-budget.md— 10W power envelope analysis
Files
jetson/
├── Dockerfile # L4T base + ROS2 Humble + SLAM packages
├── docker-compose.yml # Multi-service stack (ROS2, RPLIDAR, D435i, STM32)
├── README.md # This file
├── docs/
│ ├── pinout.md # GPIO/I2C/UART pinout reference
│ └── power-budget.md # Power budget analysis (10W envelope)
└── scripts/
├── entrypoint.sh # Docker container entrypoint
├── setup-jetson.sh # Host setup (udev, Docker, nvpmodel)
└── build-and-run.sh # Build/run helper
Power Budget (Summary)
| Scenario | Total |
|---|---|
| Idle | 2.9W |
| Nominal (SLAM active) | ~10.2W |
| Peak | 15.4W |
Target: 10W (MAXN nvpmodel). Use RPLIDAR standby + 640p D435i for compliance.
See docs/power-budget.md for full analysis.