Data Counter functions

Data Counter functions. More...

Functions
void	DMA_SetCurrDataCounter (DMA_Stream_TypeDef *DMAy_Streamx, uint16_t Counter)
	Writes the number of data units to be transferred on the DMAy Streamx. More...
uint16_t	DMA_GetCurrDataCounter (DMA_Stream_TypeDef *DMAy_Streamx)
	Returns the number of remaining data units in the current DMAy Streamx transfer. More...

Detailed Description

Data Counter functions.

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                           Data Counter functions
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  This subsection provides function allowing to configure and read the buffer size
  (number of data to be transferred). 

  The DMA data counter can be written only when the DMA Stream is disabled 
  (ie. after transfer complete event).

  The following function can be used to write the Stream data counter value:
    - void DMA_SetCurrDataCounter(DMA_Stream_TypeDef* DMAy_Streamx, uint16_t Counter);

@note It is advised to use this function rather than DMA_Init() in situations where
      only the Data buffer needs to be reloaded.

@note If the Source and Destination Data Sizes are different, then the value written in
      data counter, expressing the number of transfers, is relative to the number of 
      transfers from the Peripheral point of view.
      ie. If Memory data size is Word, Peripheral data size is Half-Words, then the value
      to be configured in the data counter is the number of Half-Words to be transferred
      from/to the peripheral.

  The DMA data counter can be read to indicate the number of remaining transfers for
  the relative DMA Stream. This counter is decremented at the end of each data 
  transfer and when the transfer is complete: 
   - If Normal mode is selected: the counter is set to 0.
   - If Circular mode is selected: the counter is reloaded with the initial value
     (configured before enabling the DMA Stream)
   
  The following function can be used to read the Stream data counter value:
     - uint16_t DMA_GetCurrDataCounter(DMA_Stream_TypeDef* DMAy_Streamx);

Function Documentation

uint16_t DMA_GetCurrDataCounter

(

DMA_Stream_TypeDef *

DMAy_Streamx

)

Returns the number of remaining data units in the current DMAy Streamx transfer.

Parameters

DMAy_Streamx,:

where y can be 1 or 2 to select the DMA and x can be 0 to 7 to select the DMA Stream.

Return values

The	number of remaining data units in the current DMAy Streamx transfer.

void DMA_SetCurrDataCounter	(	DMA_Stream_TypeDef *	DMAy_Streamx,
		uint16_t	Counter
	)

Writes the number of data units to be transferred on the DMAy Streamx.

Parameters

DMAy_Streamx,:	where y can be 1 or 2 to select the DMA and x can be 0 to 7 to select the DMA Stream.
Counter,:	Number of data units to be transferred (from 0 to 65535) Number of data items depends only on the Peripheral data format.

Note

If Peripheral data format is Bytes: number of data units is equal to total number of bytes to be transferred.

If Peripheral data format is Half-Word: number of data units is equal to total number of bytes to be transferred / 2.

If Peripheral data format is Word: number of data units is equal to total number of bytes to be transferred / 4.

In Memory-to-Memory transfer mode, the memory buffer pointed by DMAy_SxPAR register is considered as Peripheral.

Return values

The	number of remaining data units in the current DMAy Streamx transfer.