BLUENRG-1 datasheet(36/173 Pages) STMICROELECTRONICS

36 / 173 page

Functional details

BlueNRG-1

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DocID028866 Rev 1

In circular mode, after the last transfer, the DMA_CNDTRx register is automatically

reloaded with the initially programmed value. The current internal address registers are

reloaded with the base address values from the DMA_CPARx/DMA_CMARx registers.

Channel configuration procedure

The following sequence should be followed to configure a DMA channelx (where x is the

channel number).

Set the peripheral register address in the DMA_CPARx register. The data will be

moved from/ to this address to/ from the memory after the peripheral event.

Set the memory address in the DMA_CMARx register. The data will be written to or

read from this memory after the peripheral event.

Configure the total number of data to be transferred in the DMA_CNDTRx register.

After each peripheral event, this value will be decremented.

Configure the channel priority using the PL[1:0] bits in the DMA_CCRx register.

Configure data transfer direction, circular mode, peripheral & memory incremented

mode, peripheral & memory data size, and interrupt after half and/or full transfer in the

DMA_CCRx register.

Activate the channel by setting the ENABLE bit in the DMA_CCRx register.

As soon as the channel is enabled, it can serve any DMA request from the peripheral

connected on the channel. Once half of the bytes are transferred, the half-transfer flag

(HTIF) is set and an interrupt is generated if the Half-Transfer Interrupt Enable bit (HTIE) is

set. At the end of the transfer, the Transfer Complete Flag (TCIF) is set and an interrupt is

generated if the Transfer Complete Interrupt Enable bit (TCIE) is set.

Circular mode

Circular mode is available to handle circular buffers and continuous data flows (e.g. ADC

scan mode). This feature can be enabled using the CIRC bit in the DMA_CCRx register.

When circular mode is activated, the number of data to be transferred is automatically

reloaded with the initial value programmed during the channel configuration phase, and the

DMA requests continue to be served.

Memory-to-memory mode

The DMA channels can also work without being triggered by a request from a peripheral.

This mode is called Memory-to-Memory mode. If the MEM2MEM bit in the DMA_CCRx

setting the Enable bit (EN) in the DMA_CCRx register. The transfer stops once the

DMA_CNDTRx register reaches zero. Memory-to-Memory mode may not be used at the

same time as Circular mode.

BLUENRG-1 Datasheet(PDF) 36 Page - STMicroelectronics