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##

# 2.110.73 SERCOMx_I2C_CallbackRegister Function

## C

    /* x = SERCOM instance number */

    /* I2C master mode */

    void SERCOMx_I2C_CallbackRegister(SERCOM_I2C_CALLBACK callback, uintptr_t context)

    /* I2C slave in interrupt mode */

    void SERCOMx_I2C_CallbackRegister(SERCOM_I2C_SLAVE_CALLBACK callback, uintptr_t context)

## Summary

Sets the pointer to the function (and it's context) to be called when the given SERCOM I2C's transfer events occur.

## Description

This function sets the pointer to a client/application function to be called "back" when the given SERCOM I2C's transfer events occur. It also passes a context value (usually a pointer to a context structure) that is passed into the function when it is called. The specified callback function will be called from the peripheral interrupt context.

## Precondition

SERCOMx_I2C_Initialize must have been called for the associated SERCOM I2C instance.

## Parameters

Param | Description
--- | ---
callback | A pointer to a function with a calling signature defined by the SERCOM_I2C_CALLBACK (in I2C master mode) or SERCOM_I2C_SLAVE_CALLBACK (in I2C slave mode) data type. Setting this to NULL disables the callback feature.
context | A value (usually a pointer) which is passed (unused) into the function identified by the callback parameter

## Returns

None.

## Example

I2C master mode

    void SERCOM0_I2C_Callback(uintptr_t context)
    {
        if(SERCOM0_I2C_ErrorGet() == SERCOM_I2C_ERROR_NONE)
        {
            //Transfer is completed successfully
        }
        else
        {
            //Error occurred during transfer.
        }
    }

    // Register Callback function which is defined above
    SERCOM0_I2C_CallbackRegister(SERCOM0_I2C_Callback, (uintptr_t)NULL);

I2C slave in non-blocking/interrupt mode

    bool SERCOM0_I2C_Callback ( SERCOM_I2C_SLAVE_TRANSFER_EVENT event, uintptr_t context )
    {
    	uint8_t rxData;
    	uint8_t txData;

        switch(event)
        {
            case SERCOM_I2C_SLAVE_TRANSFER_EVENT_ADDR_MATCH:

            // Handle address match event

            break;

            case SERCOM_I2C_SLAVE_TRANSFER_EVENT_RX_READY:

            // I2C master is writing data to I2C slave.
            // Read the received data byte.

            rxData = SERCOM0_I2C_ReadByte();

            break;
            case SERCOM_I2C_SLAVE_TRANSFER_EVENT_TX_READY:

            // I2C master is reading data from I2C slave.
            // Provide data to I2C master.

            SERCOM0_I2C_WriteByte(txData);

            break;

            case SERCOM_I2C_SLAVE_TRANSFER_EVENT_STOP_BIT_RECEIVED:

            // Handle stop bit received event

            break;
        }
    }

    // Register Callback function which is defined above
    SERCOM0_I2C_CallbackRegister(SERCOM0_I2C_Callback, 0);

## Remarks

When I2C is configured in master mode, the callback function prototype is SERCOM_I2C_CALLBACK.

When I2C is configured in slave mode, the callback function prototype is SERCOM_I2C_SLAVE_CALLBACK.