Configure these UART pins as alternate function pull-up.
c. NVIC configuration if you need to use interrupt process
(HAL_UART_Transmit_IT() and HAL_UART_Receive_IT() APIs):
Configure the USARTx interrupt priority.
Enable the NVIC USART IRQ handle.
d. DMA Configuration if you need to use DMA process
(HAL_UART_Transmit_DMA() and HAL_UART_Receive_DMA() APIs):
Declare a DMA handle structure for the Tx/Rx stream.
Enable the DMAx interface clock.
Configure the declared DMA handle structure with the required Tx/Rx
parameters.
Configure the DMA Tx/Rx Stream.
Associate the initialized DMA handle to the UART DMA Tx/Rx handle.
Configure the priority and enable the NVIC for the transfer complete interrupt
on the DMA Tx/Rx Stream.
3. Program the Baud Rate, Word Length, Stop Bit, Parity, Hardware flow control and
Mode(Receiver/Transmitter) in the Init structure.
4. For the UART asynchronous mode, initialize the UART registers by calling the
HAL_UART_Init() API.
5. For the UART Half duplex mode, initialize the UART registers by calling the
HAL_HalfDuplex_Init() API.
6. For the LIN mode, initialize the UART registers by calling the HAL_LIN_Init() API.
7. For the Multi-Processor mode, initialize the UART registers by calling the
HAL_MultiProcessor_Init() API.
The specific UART interrupts (Transmission complete interrupt, RXNE interrupt
and Error Interrupts) will be managed using the macros
__HAL_UART_ENABLE_IT() and __HAL_UART_DISABLE_IT() inside the
transmit and receive process.
These APIs (HAL_UART_Init() and HAL_HalfDuplex_Init()) configure also the low
level Hardware GPIO, CLOCK, CORTEX...etc) by calling the customized
HAL_UART_MspInit() API.
Three operation modes are available within this driver :
Polling mode IO operation
Send an amount of data in blocking mode using HAL_UART_Transmit()
Receive an amount of data in blocking mode using HAL_UART_Receive()
Interrupt mode IO operation
Send an amount of data in non blocking mode using HAL_UART_Transmit_IT()
At transmission end of transfer HAL_UART_TxCpltCallback is executed and user can
add his own code by customization of function pointer HAL_UART_TxCpltCallback
Receive an amount of data in non blocking mode using HAL_UART_Receive_IT()
At reception end of transfer HAL_UART_RxCpltCallback is executed and user can
add his own code by customization of function pointer HAL_UART_RxCpltCallback
In case of transfer Error, HAL_UART_ErrorCallback() function is executed and user
can add his own code by customization of function pointer HAL_UART_ErrorCallback
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