API Reference

CRUMBS Class

Constructor 

CRUMBS(bool isController = false, uint8_t address = 0);
  • isController: true for controller, false for peripheral
  • address: I2C address for peripheral mode (ignored for controller)

Methods 

void begin();                                           // Initialize I2C
void sendMessage(const CRUMBSMessage &msg, uint8_t addr);  // Send message
bool receiveMessage(CRUMBSMessage &msg);                // Receive message (returns success)
void onReceive(void (*callback)(CRUMBSMessage &));      // Set receive callback
void onRequest(void (*callback)());                     // Set request callback
uint8_t getAddress() const;                             // Get device address

// Encoding/Decoding
size_t encodeMessage(const CRUMBSMessage &msg, uint8_t *buffer, size_t size);
bool decodeMessage(const uint8_t *buffer, size_t size, CRUMBSMessage &msg);

CRUMBSMessage Structure 

struct CRUMBSMessage {
    uint8_t sliceAddress;  // Target identifier (not serialized)
    uint8_t typeID;        // Module type (sensor=1, motor=2, etc.)
    uint8_t commandType;   // Command (read=0, set=1, etc.)
    float data[CRUMBS_DATA_LENGTH];  // Payload data (7 floats = 28 bytes)
    uint8_t crc8;          // CRC-8 checksum over serialized payload
};

Serialized frame: 31 bytes (typeID + commandType + data + crc8)

Constants 

#define CRUMBS_DATA_LENGTH 7       // Number of float data elements
#define CRUMBS_MESSAGE_SIZE 31     // Serialized frame size
#define TWI_CLOCK_FREQ 100000      // I2C clock frequency (100kHz)

Debug Macros 

#define CRUMBS_DEBUG               // Enable debug output
CRUMBS_DEBUG_PRINT(...)           // Print with "CRUMBS: " prefix
CRUMBS_DEBUG_PRINTLN(...)         // Print line with "CRUMBS: " prefix

Error Codes (sendMessage)

  • 0: Success
  • 1: Data too long for transmit buffer
  • 2: NACK on address (device not found)
  • 3: NACK on data transmission
  • 4: Other I2C error