1. Function description

    This routine provides a DMA usage for transferring data between peripherals and RAM.

2. Use environment

Software development environment:
        IDE tool: KEIL MDK-ARM 5.26
    
    Hardware environment:
        Development board N32L43XM-STB


3. Instructions for use

    1. Clock source: HSE+PLL
    2. Main clock: 108MHz
    3. DMA channel: DMA_CH5, DMA_CH6
    4. I2C1 configuration:
            SCL --> PB8
            SDA --> PB9
            ADDR: 0x30(7bit)
            CLOCK: 100K
    
    5. I2C2 configuration:
            SCL --> PB10
            SDA --> PB11
            ADDR: 0xA0(7bit)
            CLOCK: 100K
    
    6. USART1 configuration:
            TX --> PA9
            Baud rate: 115200
            Data bit: 8bit
            Stop bit: 1bit
            No verification
            
    7. Test steps and phenomena
a, connect PB8 to PB10, connect PB9 to PB11
        b, compile and download the code, reset and run
        c, view the printed information from the serial port and verify the result

4. Matters needing attention
    Need to add pull-up resistors on SDA and SCL