1.21.7.4 DMAC_ChainTransferSetup Function

C

bool DMAC_ChainTransferSetup( DMAC_CHANNEL channel, const void *srcAddr,
size_t srcSize, const void *destAddr, size_t destSize, size_t cellSize);

Summary

Setup a DMA channel for chain transfer

Description

This function sets up a DMA channel for chain mode of transfer. The actual transfer doesn't start by using this function.

In chained mode, more than one DMA channels are linked to each other. DMAC_ChainTransferSetup API should be used to setup all the chained channels except the first channel of the chain. First channel of the chain should be setup and enabled using DMAC_ChannelTransfer API. Once the first channel transfer is completed, next channel of the chain is automatically enabled and based on its setup, it completes the transfer and chain continues.

If callback is registered for any of the channel which is part of the chain, callback function will be called when the transfer of corresponding channel completes. The callback function will be called with a DMAC_TRANSFER_COMPLETE event if the transfer was processed successfully and a DMAC_TRANSFER_ERROR event if the transfer was not processed successfully.

When already a transfer is in progress, this API will return false indicating that transfer setup is not accepted.

Precondition

• DMAC should have been initialized by calling the DMAC_Initialize.

• Channels chaining order should be appropriately configured in MHC

configuration tree

Parameters

Returns

- true - If setup request is accepted.

- false - If previous transfer is in progress and the setup request is rejected.

Example

// Transfer 10 bytes of data to UART TX using DMAC channel 1
uint8_t buf1[10] = {0,1,2,3,4,5,6,7,8,9};
uint8_t buf2[10] = {10,11,12,13,14,15,16,17,18,19};
    void *srcAddr = (uint8_t *) buf1;
    void *destAddr = (uin8_t*) &SPI1BUF;
    size_t size = 10;
    
    // setup channel 2, it should be configured in MHC to be chained after channel 1
    DMAC_ChainTransferSetup(DMAC_CHANNEL_2, (void *)&buf2, size, destAddr, 1, 1)
    // setup and enable channel 1, once its transfer completes, channel 2 will be automatically enabled
    DMAC_ChannelTransfer(DMAC_CHANNEL_1, (void *)&buf1, size, destAddr, 1, 1)
    

Remarks

None.