gd32 uart3

### GD32 UART3 Configuration and Usage Examples

For configuring the UART3 on a GD32 microcontroller, it is essential to understand that similar principles apply as with other STM32 series devices when setting up peripherals like UARTs. The configuration involves initializing the hardware settings such as baud rate, word length, stop bits, parity check, etc., which can be done through specific registers or using an initialization structure provided by the HAL (Hardware Abstraction Layer) library.

#### Initialization of UART3 Peripheral

To initialize UART3 properly, one must first enable its clock supply within the system's RCC (Reset and Clock Control). This ensures power delivery to the peripheral before any operations are performed:

// Enable UART3 clock
RCC_APB1PeriphClockCmd(RCC_APB1Periph_UART3, ENABLE);

Next comes defining parameters for communication over UART3 including but not limited to data width, number of stop bits, whether parity checking should occur during transmission/reception sessions, and most importantly specifying desired bit rates between communicating parties[^3].

#### Setting Up Communication Parameters

The following code snippet demonstrates how these configurations might look in practice while also enabling both transmitter and receiver functionalities along with interrupt handling capabilities if needed later down the line:

UART_InitTypeDef UART_InitStructure;

// Configure UART3 parameters
UART_InitStructure.UART_BaudRate = 9600;
UART_InitStructure.UART_WordLength = UART_WordLength_8b;
UART_InitStructure.UART_StopBits = UART_StopBits_1;
UART_InitStructure.UART_Parity = UART_Parity_No ;
UART_InitStructure.UART_HardwareFlowControl = UART_HardwareFlowControl_None;
UART_InitStructure.UART_Mode = UART_Mode_Rx | UART_Mode_Tx;

// Initialize UART3 according to specified parameters in UART_InitStruct
UART_Init(UART3, &UART_InitStructure);

// Enable UART3
UART_Cmd(UART3, ENABLE);

This setup prepares UART3 for serial communications at a standard baud rate of 9600 bps without parity checks and single-stop-bit frames. Both transmit and receive modes get enabled here too so messages could flow bidirectionally once everything has been set correctly.

#### Example Code Snippet Demonstrating Data Transmission via UART3

Once initialized successfully, sending strings becomes straightforward thanks largely due to helper functions often included alongside development libraries targeting ARM Cortex-M cores found inside many modern MCUs from various manufacturers alike:

void SendString(const char* str){
    uint16_t i=0;
    
    while(str[i]!= '\0'){
        // Transmit one byte each time until null terminator reached.
        UART_SendData8(UART3,str[i++]);
        
        // Wait till last character sent out completely.
        while(!UART_GetFlagStatus(UART3,UART_FLAG_TXE));
    }
}

In this function `SendString`, characters contained within input string arguments passed into it will sequentially send them off individually across configured UART interface after converting ASCII values back into their respective bytes form suitable for binary-level processing required by underlying hardware components involved throughout entire process described above.

--related questions--

1. How does changing the UART configuration affect real-time performance?
2. What considerations need attention when selecting different baud rates for UART interfaces?
3. Can you provide more details about error-handling mechanisms available in UART implementations?
4. Is there support for DMA transfers with UART on GD32 controllers? If yes, what benefits do they offer compared to polling methods shown earlier?
5. Are there differences in configuring UART among variants of GD32 families?