Continuous Communication Using Dma; Figure 294. Irda Sir Endec- Block Diagram; Figure 295. Irda Data Modulation (3/16) -Normal Mode - ST STM32F101 series Reference Manual

Universal synchronous asynchronous receiver transmitter (USART)
TX
IrDA_OUT
IrDA_IN
RX
27.3.13

Continuous communication using DMA

The USART is capable of continuing communication using the DMA. The DMA requests for
Rx buffer and Tx buffer are generated independently.
Note: You should refer to product specs for availability of the DMA controller. If DMA is not
available in the product, you should use the USART as explained in
27.3.3. In the USART_SR register, you can clear the TXE/ RXNE flags to achieve
continuous communication.
Transmission using DMA
DMA mode can be enabled for transmission by setting DMAT bit in the USART_CR3
register. Data is loaded from a SRAM area configured using the DMA peripheral (refer to the
DMA specification) to the USART_DR register whenever the TXE bit is set. To map a DMA
channel for USART transmission, use the following procedure (x denotes the channel
number):
805/1128

Figure 294. IrDA SIR ENDEC- block diagram

TX
SIREN
USART
RX

Figure 295. IrDA data modulation (3/16) -normal mode

Start
bit
0
0
1
bit period
0
1
0
DocID13902 Rev 15
SIR
Transmit
Encoder
SIR
Receive
Decoder
0
0
1
0
0
1
USART_TX
OR
IrDA_OUT
IrDA_IN
USART_RX
stop bit
0
1 1
1
3/16
0
1
1
Section 27.3.2
RM0008
1
or