Jump to main content

##

# 1.1.6.4.7 DRV_SDMMC_AsyncWrite Function

## C

    void DRV_SDMMC_AsyncWrite (
        const DRV_HANDLE handle,
        DRV_SDMMC_COMMAND_HANDLE* commandHandle,
        void* sourceBuffer,
        uint32_t blockStart,
        uint32_t nBlock
    );

## Summary

Writes blocks of data starting at the specified address of the SD Card.

## Description

This function schedules a non-blocking write operation for writing blocks of data to the SD Card. The function returns with a valid buffer handle in the commandHandle argument if the write request was scheduled successfully. The function adds the request to the hardware instance queue and returns immediately. While the request is in the queue, the application buffer is owned by the driver and should not be modified. The function returns DRV_SDMMC_COMMAND_HANDLE_INVALID in the commandHandle argument under the following circumstances:

- if the driver handle is invalid
- if the source buffer pointer is NULL
- if the number of blocks to write is zero or more than the actual number of blocks available
- if a buffer object could not be allocated to the request

If the requesting client registered an event callback with the driver, the driver will issue a DRV_SDMMC_EVENT_COMMAND_COMPLETE event if the buffer was processed successfully or DRV_SDMMC_EVENT_COMMAND_ERROR event if the buffer was not processed successfully.

## Precondition

The DRV_SDMMC_Initialize routine must have been called for the specified SDMMC driver instance.

DRV_SDMMC_Open routine must have been called to obtain a valid opened device handle.

## Parameters

Param | Description
--- | ---
handle | A valid open-instance handle, returned from the driver's open function
commandHandle | Pointer to an argument that will contain the return buffer handle
sourceBuffer | The source buffer containing data to be programmed to the SD Card.
blockStart | Start block address of SD Card where the writes should begin.
nBlock | Total number of blocks to be written.

## Returns

The buffer handle is returned in the commandHandle argument. It will be DRV_SDMMC_COMMAND_HANDLE_INVALID if the request was not successful.

## Example

    uint8_t CACHE_ALIGN myBuffer[MY_BUFFER_SIZE];

    // address should be block aligned.
    uint32_t blockStart = 0x00;
    uint32_t nBlock = 2;
    DRV_SDMMC_COMMAND_HANDLE commandHandle;
    MY_APP_OBJ myAppObj;

    // Event is received when the buffer is processed.

    void APP_SDMMCEventHandler(
        DRV_SDMMC_EVENT event,
        DRV_SDMMC_COMMAND_HANDLE commandHandle,
        uintptr_t contextHandle
    )
    {
        // contextHandle points to myAppObj.

        switch(event)
        {
            case DRV_SDMMC_EVENT_COMMAND_COMPLETE:
            {
                // This means the data was transferred successfully
                break;
            }

            case DRV_SDMMC_EVENT_COMMAND_ERROR:
            {
                // Error handling here
                break;
            }

            default:
            {
                break;
            }
        }
    }

    // mySDMMCHandle is the handle returned
    // by the DRV_SDMMC_Open function.

    // Client registers an event handler with driver

    DRV_SDMMC_EventHandlerSet(mySDMMCHandle, APP_SDMMCEventHandler, (uintptr_t)&myAppObj);

    DRV_SDMMC_AsyncWrite(mySDMMCHandle, &commandHandle, &myBuffer[0], blockStart, nBlock);

    if(commandHandle == DRV_SDMMC_COMMAND_HANDLE_INVALID)
    {
        // Error handling here
    }

## Remarks

None.