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##

# 1.1.8.4.12 DRV_SPI_WriteTransfer Function

## C

    void DRV_SPI_WriteTransfer
    (
        const DRV_HANDLE handle,
        void* pTransmitData,
        size_t txSize
    );

## Summary

This is a blocking function that transmits data over SPI.

## Description

This function does a blocking write operation. The function blocks till the data transmit is complete. Function will return true if the transmit is successful or false in case of an error. The failure will occur for the following reasons:

- if the handle is invalid
- if the pointer to the transmit buffer is NULL
- if the transmit size is 0

## Precondition

- DRV_SPI_Open must have been called to obtain a valid opened device handle.
- DRV_SPI_TransferSetup must have been called if GPIO pin has to be used for

chip select or any of the setup parameters has to be changed dynamically.

## Parameters

Param | Description
--- | ---
handle | Handle of the communication channel as returned by the DRV_SPI_Open function.
*pTransmitData | Pointer to the data which has to be transmitted.
txSize | Number of bytes to be transmitted. The size must be specified in terms of the SPI data width. For example, if the data width is 8-bits, and if 10 bytes are being transmitted, then the txSize must be set to 10. If the data width is 16-bits then transmitting 10 bytes requires specifying the txSize as 10 (meaning 10 16-bit words).

## Returns

true - transfer is successful

false - error has occurred

## Example

    MY_APP_OBJ myAppObj;
    uint8_t myTxBuffer[MY_TX_BUFFER_SIZE];

    // mySPIHandle is the handle returned by the DRV_SPI_Open function.

    if (DRV_SPI_WriteTransfer(mySPIhandle, myTxBuffer, MY_TX_BUFFER_SIZE) == false)
    {
        // Handle error here
    }

## Remarks

- This function is thread safe in a RTOS application.
- This function should not be called from an interrupt context.