Two operating modes are available:
Polling mode I/O operation
a. Use HAL_DMA_Start() to start DMA transfer when the source and destination
addresses and the Length of data to be transferred have been configured.
b. Use HAL_DMA_PollForTransfer() to poll for the end of current transfer. In this
case a fixed timeout can be configured depending on the user application.
Interrupt mode I/O operation
a. Configure the DMA interrupt priority using HAL_NVIC_SetPriority()
b. Enable the DMA IRQ handler using HAL_NVIC_EnableIRQ()
c. Use HAL_DMA_Start_IT() to start DMA transfer when the source and destination
addresses and the length of data to be transferred have been confgured. In this
case the DMA interrupt is configured.
d. Use HAL_DMA_IRQHandler() called under DMA_IRQHandler() Interrupt
subroutine
e. When data transfer is complete, HAL_DMA_IRQHandler() function is executed
and a user function can be called by customizing XferCpltCallback and
XferErrorCallback function pointer (i.e. a member of DMA handle structure).
Additional functions and macros are available to ensure efficient DMA management:
Use HAL_DMA_GetState() function to return the DMA state and
HAL_DMA_GetError() in case of error detection.
Use HAL_DMA_Abort() function to abort the current transfer
The most used DMA HAL driver macros are the following:
__HAL_DMA_ENABLE: enablse the specified DMA Channels.
__HAL_DMA_DISABLE: disables the specified DMA Channels.
__HAL_DMA_GET_FS: returns the current DMA Stream FIFO filled level.
__HAL_DMA_GET_FLAG: gets the DMA Channels pending flags.
__HAL_DMA_CLEAR_FLAG: clears the DMA Channels pending flags.
__HAL_DMA_ENABLE_IT: enables the specified DMA Channels interrupts.
__HAL_DMA_DISABLE_IT: disables the specified DMA Channels interrupts.
__HAL_DMA_GET_IT_SOURCE: checks whether the specified DMA stream interrupt
has occurred or not.
When a peripheral is used in DMA mode, the DMA initialization should be done in
the HAL_PPP_MspInit() callback. In addition, the user application should
associate the DMA handle to the PPP handle (refer to section “HAL IO operation
functions”).
DMA double-buffering feature is handled as an extension API.
DMA channel callbacks need to be initialized by the user application only in case
of memory-to-memory transfer. However when peripheral-to-memory transfers
are used, these callbacks are automatically initialized by calling a process API
function that uses the DMA.
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