1.8.10.4 MCSPIx_Write Function

C

/* x = MCSPI instance number */

/* MCSPI master mode */
bool MCSPIx_Write(void* pWrBuffer, size_t txSize)		

/* x = MCSPI instance number */

/* MCSPI slave mode */
size_t MCSPIx_Write(void* pWrBuffer, size_t txSize )			

Summary

Writes data to MCSPI peripheral

Description

MCSPI master mode

This function writes "txSize" number of bytes on MCSPI module. Data pointed by pWrBuffer is transmitted. When interrupt is disabled, this function will be blocking in nature. In this mode, the function will not return until all the requested data is transferred. The function returns true after transferring all the data. This indicates that the operation has been completed. When interrupt is enabled, the function will be non-blocking in nature. The function returns immediately. The data transfer process continues in the peripheral interrupt. The application specified transmit buffer is owned by the library until the data transfer is complete and should not be modified by the application till the transfer is complete. Only one transfer is allowed at any time. The application can use a callback function or a polling function to check for completion of the transfer. If a callback is required, this should be registered prior to calling the MCSPIx_Write() function. The application can use the MCSPIx_IsBusy() to poll for completion of transfer.

MCSPI slave mode

This function writes "txSize" number of bytes on MCSPI module. Data pointed by pWrBuffer is transmitted. This function returns immediately after copying the data pointed by pWrBuffer into the PLIB's internal buffer. The actual data transfer happens when a MCSPI transfer is initiated by the MCSPI master. Upon completion a callback is given to the application.

Precondition

The MCSPIx_Initialize function must have been called.

MCSPI master mode

Callback can be registered using MCSPIx_CallbackRegister API if the PLIB is configured in Interrupt mode and transfer completion status needs to be communicated back to application via callback.

MCSPI slave mode

Callback must have been registered using MCSPIx_CallbackRegister API to get notified when the transfer is complete.

Parameters

MCSPI master mode

MCSPI slave mode

Returns

MCSPI master mode

true - If configured for Non-interrupt mode, the function has transmitted the requested number of bytes. If configured for Interrupt mode, the request was accepted successfully and will be processed in the interrupt.

false - If pWrBuffer is NULL or txSize is 0. In Interrupt mode, the function will additionally return false if there is an on-going data transfer at the time of calling the function.

MCSPI slave mode

Returns the number of bytes actually copied from the pWrBuffer. If 16/32 bit modes are supported, the return value is specified in terms of 16/32 bit words.

Example

MCSPI master mode

uint8_t txBuffer[4];
size_t txSize = 4;

void APP_MCSPITransferHandler(uintptr_t context)
{
    //Transfer was completed without error, do something else now.
}

MCSPI1_Initialize();
MCSPI1_CallbackRegister(&APP_MCSPITransferHandler, (uintptr_t)NULL);
if(MCSPI1_Write(&txBuffer, txSize))
{
    // request got accepted
}
else
{
    // request didn't get accepted, try again later with correct arguments
}

MCSPI slave mode

uint8_t APP_TxData[4];
uint8_t APP_RxData[10];
size_t txSize = 4;

void MCSPIEventHandler(uintptr_t context )
{
    if (MCSPI1_ErrorGet() == MCSPI_SLAVE_ERROR_NONE)
    {
        // Read out the received data. This could be meaningful data if MCSPI master is
        // writing to slave or it could be dummy data if MCSPI master is reading from slave.
        // However, irrespective of whether slave is expecting meaningful data or dummy
        // data from master, MCSPI slave must always read out the data to clear the PLIB's
        // internal receive buffer.

        appData.nBytesRead = MCSPI1_Read(APP_RxData, MCSPI1_ReadCountGet());
    }
    else
    {
        // Handle error
    }

}

MCSPI1_CallbackRegister(MCSPIEventHandler, (uintptr_t) 0);
MCSPI1_Write(APP_TxData, txSize);

Remarks

MCSPI slave mode

This function returns immediately. Application must register a callback to get notified, when the data transfer is complete. A data transfer is considered as complete, when the Chip Select line is driven to inactive state by the MCSPI master.