SamsungNASA - Samsung NASA Protocol Library for ESP32

An Arduino library for communicating with Samsung HVAC systems using the NASA protocol over RS485. Optimized exclusively for ESP32 with FreeRTOS async packet handling. For AVR architecture check this: SamsungNASA-AVR

Features

• Full NASA Protocol Implementation - Complete encoding/decoding based on relativly new (but unknown) version of the protocol
• ESP32 Optimized - Uses FreeRTOS for async packet handling
• RS485 Support - Built-in RE/DE pin control for RS485 transceivers
• CRC16 Validation - Automatic packet integrity checking
• Callback Architecture - Easy-to-use event-driven packet handling
• All Message Types - Supports Enum, Variable, LongVariable, and Structure messages
• Flexible Device Types - Configure as any NASA protocol device (default: Undefined)

Hardware Requirements

• ESP32 development board (any variant)
• RS485 Transceiver module (e.g. MAX3485, or similar)
• Connection to Samsung HVAC system NASA bus

Wiring

RS485 Module          ESP32
─────────────────────────────
RO (Receiver Out) →   GPIO16 (RX)
DI (Driver In)    →   GPIO17 (TX)
RE (Recv Enable)  →   GPIO4
DE (Driver Enable)→   GPIO4 (connect RE and DE together)
VCC               →   3.3V
GND               →   GND

RS485 A/B         →   Samsung F1/F2 or R1/R2 (Select proper BUS_TYPE)

Protocol Details

Packet Structure

┌────────┬──────┬──────┬────────┬──────────┬─────────┬──────────┬────────┬─────┬────────┐
│ Start  │ Size │ Size │ Source │ Dest.    │ Command │ Msg      │ Data   │ CRC │ End    │
│ (0x32) │ (HI) │ (LO) │ (3B)   │ (3B)     │ (3B)    │ Count    │ (var)  │ (2B)│ (0x34) │
└────────┴──────┴──────┴────────┴──────────┴─────────┴──────────┴────────┴─────┴────────┘

Message Types

• Enum (Type 0): 1-byte value (e.g., ON/OFF, mode selection)
• Variable (Type 1): 2-byte value (e.g., temperature, fan speed)
• LongVariable (Type 2): 4-byte value (e.g., power consumption)
• Structure (Type 3): Variable length structured data

Temperature Encoding

Temperatures are encoded as value * 10:

• 24.0°C → 240
• 18.5°C → 185
• 30.0°C → 300

Troubleshooting

No packets received

1. Check wiring (especially A/B polarity)
2. Verify baud rate (usually 9600)
3. Ensure RS485 module is powered correctly
4. Check RE/DE pin is connected and configured

CRC errors

1. Check for electrical noise on RS485 bus
2. Ensure proper grounding
3. Use twisted pair cable for longer runs
4. Add termination resistors if needed (120Ω)

Advanced Usage

Custom Device Types

// Act as a central controller
nasa.begin(9600, 16, 17, 4, AddressClass::CentralController, 0, 1);

Packet Filtering

void onPacketReceived(const NASAPacket& packet) {
  // Only process packets from indoor units
  if (packet.getSourceAddress().getClass() != AddressClass::Indoor) {
    return;
  }

  // Process packet...
}

Broadcasting

// Send to all indoor units
NASAAddress broadcast(AddressClass::BroadcastControlLayer, 0, 0);
NASAPacket packet = nasa.createPacket(broadcast, DataType_Notification);
// Add messages and send...

License

MIT License - See LICENSE file for details

Contributing

Contributions are welcome! Please:

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Submit a pull request

Credits

Based on the Samsung NASA protocol reverse engineering efforts and few surfaced documents.

Thanks to the contributors of ESPHome Samsung HVAC Integration for interpreting some of the protocol addresses.

Disclaimer

This library is intended for educational use in home and educational applications and is not affiliated with or endorsed by Samsung. Use at your own risk. Always comply with local regulations regarding modifications to HVAC systems.