Master Device

Overview of basic functions for I2C communication with Feelix

Download the library with example codes here. Version 1.8 and later.

Define the addresses for each of the slaves that will be connected to the master.

#define SLAVE_0_ADDRESS 0x70
#define SLAVE_1_ADDRESS 0x71
#define SLAVE_2_ADDRESS 0x72

Create MasterDevice object. Pass an array with the addresses of all slaves as argument.

uint8_t slaves[] = { SLAVE_0_ADDRESS, SLAVE_1_ADDRESS };

/* initialize master device */
MasterDevice I2C_Master(slaves);

Initialization

Initialize master device in void setup()

/* initialize as Master device */
I2C_Master.init(
    ESP32_SDA,              //I2C Data (SDA)
    ESP32_SCL,              //I2C Clock (SCL)
    CLOCK_SPEED::SLOW_MODE, //Clock frequency 
                            // CLOCK_SPEED::SLOW_MODE = 100000 
                            // CLOCK_SPEED::FAST_MODE = 400000 
    DEBUG,                  //(optional) 
                            // bool debug (set to false before production)
    callbackArr,            //(optional)
                            // array with callback functions (functionPtr)
    callbackLength);        //(optional) size of array

Receiving motor parameters

Request motor parameters (angle, velocity, voltage, status) from slave device in void loop()

I2C_Master.requestDeviceParameters(SLAVE_0_ADDRESS)

Create a callback function to receive the device parameters from the slave. Call before void setup()

/* callback to receive parameters from slave */
void callBack_receiveParameter_slave() {
    I2C_Master.receiveDeviceParameters(); // masterCallbackIndex 0
}

/* array to store callback functions */
const functionPtr callbackArr[] = { 
    callBack_receiveParameter_slave //masterCallbackIndex 0
};
/* calculate length of array (do not change) */
uint8_t callbackLength = sizeof(callbackArr)/sizeof(functionPtr);

The received data is stored in the following variables

I2C_Master.slaves[slaveIndex].motor.angle
I2C_Master.slaves[slaveIndex].motor.velocity
I2C_Master.slaves[slaveIndex].motor.voltage
I2C_Master.slaves[slaveIndex].motor.status

Sending variables to slave

Send a float variable to the slave. The function triggers a callback at the slave side at slaveCallbackIndex of the callback array.

• float data,

• uint8_t slaveAddress,

• uint8_t slaveCallbackIndex

 float velocity = 3.0; 
 I2C_Master.sendFloat(velocity, SLAVE_0_ADDRESS, 0);

Send an integer variable to the slave. The function triggers a callback at the slave side at slaveCallbackIndex of the callback array.

• int16_t data,

• uint8_t slaveAddress,

• uint8_t slaveCallbackIndex

 int16_t randomVariable = random(10000);
 I2C_Master.sendInt(randomVariable, SLAVE_0_ADDRESS, 1);

Send a byte variable to the slave. The function triggers a callback at the slave side at slaveCallbackIndex of the callback array.

• uint8_t data,

• uint8_t slaveAddress,

• uint8_t slaveCallbackIndex

 uint8_t activeEffect = !activeEffect;
 I2C_Master.sendByte(activeEffect, SLAVE_0_ADDRESS, 2);

Send a char array to the slave. The function triggers a callback at the slave side at slaveCallbackIndex of the callback array.

• char (&data)[]

• uint16_t dataSize

• uint8_t slaveAddress,

• uint8_t slaveCallbackIndex

char arr[] = "hello";
I2C_Master.sendCharArray(arr, sizeof(arr), SLAVE_0_ADDRESS, 3);