⚠️ ASPIRATIONAL — THIS IS NOT WHAT SHIPS.
This document describes a design in which an FSWConfigManager assigns board IPs by MAC hash and boards report their assignments back over heartbeats. No such component exists in the running system.
What actually ships: board identity and sensor assignment are a static table in config/config.toml ([boards.*], [sensor_roles_*], [actuator_roles]), broadcast to boards unconditionally by config_broadcast_service roughly once a second. Boards are addressed at fixed IPs from that table; nothing is negotiated and nothing is reported back.
Read docs/CONFIGURATION_GUIDE.md for the real model. Keep this only as a record of the intended direction — do not use it to reason about current behaviour, and do not file bugs against the gap between the two.
Overview
The sensor assignment system manages the distribution of sensors to boards, IP assignment, and configuration distribution. The FSW (Flight Software) side assigns IP addresses and sensor configurations to boards, which then report back their assigned sensors.
Architecture
┌─────────────────────────────────────────────────────────┐
│ FSW Configuration Manager │
├─────────────────────────────────────────────────────────┤
│ │
│ ┌──────────────┐ ┌──────────────┐ │
│ │ IP │ │ Sensor │ │
│ │ Assignment │ │ Assignment │ │
│ └──────┬───────┘ └──────┬───────┘ │
│ │ │ │
│ └──────────┬────────────┘ │
│ │ │
│ ┌──────────▼──────────┐ │
│ │ Config Generator │ │
│ │ (SENSOR_CONFIG) │ │
│ └──────────┬──────────┘ │
│ │ │
│ ┌──────────▼──────────┐ │
│ │ UDP Socket │ │
│ │ Send to Board │ │
│ └────────────────────┘ │
└─────────────────────────────────────────────────────────┘
│
▼
┌────────────────────┐
│ Board (ESP32) │
│ Receives Config │
│ Configures Sensors│
└────────────────────┘
System States
GSE (Ground Support Equipment)
- Network: 192.168.2.0/24
- IP Range: 192.168.2.100-150
- Components:
- Pressurant Fill (PT_HPF, PT_MPF, PT_LPF)
- Fuel Fill (PT_FF)
- LOX Fill (PT_OF)
FLIGHT (Rocket System)
- Network: 192.168.3.0/24
- IP Range: 192.168.3.100-150
- Sensors:
- High Pressure (PT_HP)
- COPV Post Regulator (PT_LP)
- Fuel Upstream/Downstream (PT_FUP, PT_FDP)
- Oxidizer Upstream/Downstream (PT_OUP, PT_ODP)
Sensor Definitions
Flight Pressure Sensors
| Sensor ID | Name | Max PSI | Purpose | Board | Channel |
| PT_HP | High Pressure PT | 5000 | High pressure reading | 0 | 0 |
| PT_LP | COPV PT Post Regulator | 1000 | COPV post regulator | 0 | 1 |
| PT_FUP | Upstream Fuel PT | 1000 | Fuel upstream | 1 | 0 |
| PT_FDP | Downstream Fuel PT | 1000 | Fuel downstream | 1 | 1 |
| PT_OUP | Upstream Oxidizer PT | 1000 | Oxidizer upstream | 2 | 0 |
| PT_ODP | Downstream Oxidizer PT | 1000 | Oxidizer downstream | 2 | 1 |
GSE Pressure Sensors
| Sensor ID | Name | Max PSI | Purpose | Component | Board | Channel |
| PT_OF | LOX Fill PT | 1000 | LOX fill pressure | LOX Fill | 10 | 0 |
| PT_FF | Fuel Fill PT | 1000 | Fuel fill pressure | Fuel Fill | 11 | 0 |
| PT_HPF | High Pressure Fill PT | 5000 | High pressure fill | Pressurant Fill | 12 | 0 |
| PT_MPF | Medium Pressure Fill PT | 2000 | Medium pressure fill | Pressurant Fill | 12 | 1 |
| PT_LPF | Low Pressure Fill PT | 1000 | Low pressure fill | Pressurant Fill | 12 | 2 |
IP Assignment Algorithm
IP addresses are assigned deterministically based on MAC address:
uint32_t mac_hash = hash_mac(mac_address);
if (system_state == GSE) {
base_ip = "192.168.2.0";
range = 100-150;
} else {
base_ip = "192.168.3.0";
range = 100-150;
}
ip_octet = range_start + (mac_hash % (range_end - range_start + 1));
assigned_ip = base_ip + "." + ip_octet;
Benefits:
- Same board always gets same IP
- Survives reboots
- No conflicts
- Works with static IPs too
Configuration Packet Format
FSW sends SENSOR_CONFIG packets to boards:
PacketHeader (6 bytes):
packet_type = SENSOR_CONFIG (5)
version = 0
timestamp = millis()
Body:
num_sensors (1 byte)
sensor_ids[] (N bytes, channel IDs)
necessary_for_abort (1 byte)
controller_ip (4 bytes, if necessary_for_abort)
Example:
- Board 0 (Flight): [5, 0, timestamp, 2, 0, 1, 0]
- 2 sensors: channels 0, 1
- Sensors: PT_HP (ch0), PT_LP (ch1)
Workflow
1. Board Discovery
- Board sends BOARD_HEARTBEAT packet
- FSW receives heartbeat
- FSW assigns IP address based on MAC
- FSW assigns sensors based on board_id and system state
2. Configuration Distribution
- FSW generates SENSOR_CONFIG packet
- FSW sends packet to board's assigned IP
- Board receives config and configures sensors
- Board sends acknowledgment (optional)
3. Sensor Data Collection
- Board reads sensors according to configuration
- Board sends SENSOR_DATA packets
- DAQ Bridge receives and routes to Elodin
- Data appears in Elodin editor
Usage Example
fsw::FSWConfigManager fsw_config;
fsw_config.initialize("0.0.0.0", 5006);
fsw_config.set_system_state(config::SystemState::GSE);
auto heartbeat = parse_board_heartbeat(packet_data, packet_size);
std::string assigned_ip = fsw_config.process_board_heartbeat(
heartbeat, source_ip, mac_address);
fsw_config.assign_sensors(10, {"PT_OF"}, 0);
fsw_config.send_config_to_board(10);
Configuration File Structure
[system]
state = "GSE" # or "FLIGHT"
[system.network]
# Ground and flight do NOT live in the same file. Each side has its own
# config file, each with its own [system.network] base_ip:
# - config_ground_daq.toml → base_ip = "192.168.2.0"
# - config_flight_daq.toml → base_ip = "192.168.3.0"
base_ip = "192.168.2.0" # (ground example; flight file uses 192.168.3.0)
ip_range_start = 100
ip_range_end = 150
[sensors.flight.pt]
PT_HP = { board_id = 0, channel = 0, max_psi = 5000 }
PT_LP = { board_id = 0, channel = 1, max_psi = 1000 }
# ... etc
[sensors.gse.pt]
PT_OF = { board_id = 10, channel = 0, max_psi = 1000, component = "lox_fill" }
# ... etc
Next Steps
- Actuators: Add actuator assignments
- RTDs: Add RTD sensor assignments
- TCs: Add thermocouple assignments
- LCs: Add load cell assignments
- Validation: Verify sensor assignments match hardware
- Error Handling: Robust error handling for failed assignments
- Persistence: Save assignments to config file
1.15.0