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##

# 1.3.2.4.5 I2C_BB_WriteRead Function

## C

    bool I2C_BB_WriteRead(uint16_t address, uint8_t* wdata, size_t wlength, uint8_t* rdata, size_t rlength)

## Summary

Write and Read data from Slave.

## Description

This function writes data from the wdata to the bus and then reads data from the slave and stores the received in the rdata. The function generates a Start condition on the bus and will then send wlength number of bytes contained in wdata. The function will then insert a Repeated start condition and proceed to read rlength number of bytes from the slave. The received bytes are stored in rdata buffer. A Stop condition is generated after the last byte has been received.

If the slave NAKs the request , the transfer is terminated. The application can call I2C_BB_ErrorGet() function to know that cause of the error.

The function is non-blocking. It initiates bus activity and returns immediately. The transfer is then completed in the timer peripheral interrupt. A transfer request cannot be placed when another transfer is in progress. Calling this function when another function is already in progress will cause the function to return false.

The library will call the registered callback function when the transfer has terminated.

## Precondition

I2C_BB_Initialize must have been called for the associated I2C instance.

## Parameters

Param | Description
--- | ---
address | 7-bit / 10-bit slave address.
wdata | pointer to write data buffer
wlength | write data length in bytes.
rdata | pointer to read data buffer.
rlength | read data length in bytes.

## Returns

true - The request was placed successfully and the bus activity was initiated.

false - The request fails, if there was already a transfer in progress when this function was called.

## Example

    uint8_t myTxData [NUM_TX_BYTES] = {'1', '0', ' ', 'B', 'Y', 'T', 'E', 'S'};
    uint8_t myRxData [NUM_RX_BYTES] = {0};

    void MyI2CCallback(uintptr_t context)
    {
        // This function will be called when the transfer completes. Note
        // that this function executes in the context of the I2C interrupt.
    }

    I2C_BB_Initialize();

    I2C_BB_CallbackRegister(MyI2CCallback, NULL);

    if(I2C_BB_WriteRead( SLAVE_ADDR, &myTxData[0], NUM_TX_BYTES, myRxData, NUM_RX_BYTES ) == false)
    {
        // error handling
    }

## Remarks

Calling this function is not the same as calling the I2C_BB_Write() function and then calling the I2C_BB_Read() function.

The I2C_BB_WriteRead function will insert a Repeated Start condition between the Write and the Read stages. The I2C_BB_Write() and the I2C_BB_Read() function insert a stop condition after the write and the read has completed.