Marine electronics rely on NMEA 2000 (N2K), a standardized protocol built on top of Bosch CAN 2.0B (Controller Area Network) operating at 250 kbps with J1939-based 29-bit identifiers.

In this project, we design an isolated hardware gateway that bridges N2K PGN messages directly into an MQTT stream for vessel dashboards.

Hardware Architecture & Galvanic Isolation

Boats often have multiple battery banks with distinct ground references. Directly connecting an ESP32 to the CAN bus without isolation risks ground loops, alternator noise, and damaged silicon.

 [NMEA 2000 Micro-C Bus]
           │
     [CAN Transceiver: ISO1050] (Galvanic Isolation 5kV)
           │
    [ESP32-S3 TWAI Controller] (Two-Wire Automotive Interface)
           │
  [Wi-Fi 802.11 / MQTT Broker]

Parsing Engine Parameters (PGN 127488)

PGN 127488 transmits Rapid Engine Data including engine speed and boost pressure.

#include <Arduino.h>
#include <NMEA2000_CAN.h>
#include <N2kMessages.h>

void HandleEngineData(const tN2kMsg &N2kMsg) {
    unsigned char engineInstance;
    double engineSpeed;
    double engineBoost;
    int8_t engineTilt;

    if (ParseN2kEngineParamRapid(N2kMsg, engineInstance, engineSpeed, engineBoost, engineTilt)) {
        Serial.printf("[Engine #%d] RPM: %.1f | Boost: %.2f kPa\n", 
                      engineInstance, 
                      engineSpeed, 
                      engineBoost / 1000.0);
    }
}

Key PGN Reference Table

By packaging these telemetry frames into lightweight JSON payloads over MQTT, we achieve sub-100ms latency on tablet charts and remote vessel telemetry.