Tmini-Plus lidar-Reading data (USART)

The tutorial demonstrates how to receive radar data via serial port 3 and print the distance values corresponding to each angle of the radar via serial port 1.

The tutorial only introduces the standard library project code

Hardware connection

Since we have configured a special connection line, we only need to install it to the corresponding interface:

Control principle

• Tmini-Plus radar

** Radar angle distribution**

The arrow in the center of the radar points to 0°/360°, and the angle increases clockwise.

Communication protocol

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For detailed information, please refer to the "T_Mini_Plus Manual"

Software configuration

Pin definition

Software code

Since the default pin function is a normal IO pin function, we need to use the redefine function.

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Product supporting materials source code path: Attachment → Source code summary → 2. Extended_Course → 12. Tmini-Plus_Ladar

Control function

The tutorial only briefly introduces the code, you can open the project source code to read it in detail.

USART3_init

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void USART3_init(u32 baudrate)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    USART_InitTypeDef USART_InitStructure;
    NVIC_InitTypeDef NVIC_InitStructure; 
    
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART3, ENABLE);
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC |RCC_APB2Periph_AFIO, ENABLE);
    
    GPIO_PinRemapConfig(GPIO_PartialRemap_USART3, ENABLE);
    
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOC, &GPIO_InitStructure);    

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    GPIO_Init(GPIOC, &GPIO_InitStructure);
      
    USART_InitStructure.USART_BaudRate = baudrate;
    USART_InitStructure.USART_WordLength = USART_WordLength_8b;
    USART_InitStructure.USART_StopBits = USART_StopBits_1;
    USART_InitStructure.USART_Parity = USART_Parity_No ;
    USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
    USART_Init(USART3, &USART_InitStructure); 
    USART_ITConfig(USART3, USART_IT_TXE, DISABLE);  
    USART_ITConfig(USART3, USART_IT_RXNE, ENABLE);      
    //USART_ClearFlag(USART3,USART_FLAG_TC);
    USART_Cmd(USART3, ENABLE);
    
    NVIC_InitStructure.NVIC_IRQChannel = USART3_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 3;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);
}

USART3_IRQHandler

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void USART3_IRQHandler(void)
{
    uint8_t Rx3_Temp;
    if (USART_GetITStatus(USART3, USART_IT_RXNE) != RESET)
    {
        USART_ClearITPendingBit(USART3, USART_IT_RXNE);
        Rx3_Temp = USART_ReceiveData(USART3);
        recv_lidar_data(Rx3_Temp);
    }
}

recv_lidar_data

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void recv_lidar_data(u8 rxtemp)
{
    static uint8_t step = 0;
    static uint16_t si_len = 0;
    static uint8_t si_index = 0;
    switch(step)
    {
        
        case 0:
            if(rxtemp == Lidar_HeaderLSB)
            {
                step = 1;
                g_recvbuf[0] = Lidar_HeaderLSB; 
            }   
        break;
        
        case 1:
            if(rxtemp == Lidar_HeaderMSB) 
            {
                step = 2;
                g_recvbuf[1] = Lidar_HeaderMSB; 
            }
        break;
            
        case 2: g_recvbuf[step] = rxtemp; step++; break; // CT Information
        case 3: g_recvbuf[step] = rxtemp; step++; si_len = rxtemp * 3; // Number of S
            
            // Here we judge whether the data length is greater than the cache.
            if(si_len+10>=TempLen_Max)
            {
                    si_len = 0;
                    step = 0;
                    memset(g_recvbuf,0,sizeof(g_recvbuf));
            }               
            break; 
            
        case 4: g_recvbuf[step] = rxtemp; step++;  break; //Start angle low 8 bits
        case 5: g_recvbuf[step] = rxtemp; step++;  break; //Start angle high 8 bits
        case 6: g_recvbuf[step] = rxtemp; step++;  break; //End angle low 8 bits
        case 7: g_recvbuf[step] = rxtemp; step++;  break; //End angle high 8 bits
        case 8: g_recvbuf[step] = rxtemp; step++;  break; //Check code low 8 bits
        case 9: g_recvbuf[step] = rxtemp; step++;  break; //Check code high 8 bits
                
        case 10:
        {
                g_recvbuf[step + si_index] = rxtemp;  
                si_index++;
                
                if(si_index >= si_len )
                {
                    Deal_Radar();
                    si_index = 0;
                    si_len = 0;
                    step = 0;
                    memset(g_recvbuf,0,sizeof(g_recvbuf));
                }
                break;
        }
    }
}

Experimental phenomenon

The Tmini-Plus_Ladar.hex file generated by the project compilation is located in the OBJ folder of the Tmini-Plus_Ladar project. Find the Tmini-Plus_Ladar.hex file corresponding to the project and use the FlyMcu software to download the program into the development board.

After the program is successfully downloaded: the serial port will print the radar angle and its corresponding distance.