Lidar’s are used in flight modes which have height control, such as Altitude Hold, Loiter and PosHold Mode. The data from the sensor will be used until you exceed RNGFND_MAX_CM, after that it switches to the barometer. Currently Lidar is not supported in Auto Mode.

// Global Variables

u16 distance = 0;

// Variables used by serial

static u8 Usart1buf[USART1_BUF_SIZE];

static u8 pointer = 0;

// Serial Port 1 Function Initialize

void USART1_Init(void)

{       

         USART_InitTypeDef USART1_InitStructure;

         GPIO_InitTypeDef GPIO_InitStructure;

         NVIC_InitTypeDef NVIC_InitStructure;

         // GPIOA Clock

         RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);

         // A9 -> TX  ,  A10 -> RX

         GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9 | GPIO_Pin_10;

         GPIO_InitStructure.GPIO_Speed = GPIO_High_Speed;

         GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;

         GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;

         GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;

         GPIO_Init(GPIOA,&GPIO_InitStructure);

         // Alternative Function Configuration

         GPIO_PinAFConfig(GPIOA,GPIO_PinSource9,GPIO_AF_USART1);

         GPIO_PinAFConfig(GPIOA,GPIO_PinSource10,GPIO_AF_USART1);

         // USART1 clock

         RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);

         // USART1 Interrupt Priority

         NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;

         NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;

         NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;

         NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

         NVIC_Init(&NVIC_InitStructure);

         // USART1 Initialize

         USART_DeInit(USART1);

         USART1_InitStructure.USART_BaudRate = 115200;

         USART1_InitStructure.USART_WordLength = USART_WordLength_8b;

         USART1_InitStructure.USART_StopBits = USART_StopBits_1;

         USART1_InitStructure.USART_Parity = USART_Parity_No;

         USART1_InitStructure.USART_Mode = USART_Mode_Rx|USART_Mode_Tx;

         USART1_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;

         USART_Init(USART1,&USART1_InitStructure);

         USART_Cmd(USART1,ENABLE);

         USART_ITConfig(USART1,USART_IT_RXNE,ENABLE);

}

// Serial Interrupt Function

void USART1_IRQHandler(void)

{

         if(USART_GetITStatus(USART1, USART_IT_RXNE) != RESET

            || (USART_GetITStatus(USART1, USART_IT_ORE_RX) != RESET))

         {

                   USART_ClearITPendingBit(USART1, USART_IT_RXNE);

                   Usart1buf[pointer++%USART1_BUF_SIZE] = USART_ReceiveData(USART1);

                   // Receive data program

                   if((pointer%USART1_BUF_SIZE >= 9))

                   {

                            // Check the head and the tail of the packet

                            // Better do a checksum, not written here

                            if(   (Usart1buf[pointer%USART1_BUF_SIZE-3]==0x59)

                                     &&(Usart1buf[pointer%USART1_BUF_SIZE-4]==0x59))

                            {

                                     //Distance

                                     distance=((u16)((Usart1buf[pointer%USART1_BUF_SIZE-1])<<8)

                                                    |(u16)(Usart1buf[pointer%USART1_BUF_SIZE-2]));

                            }

                   }

         }

}

void DAC_Config(void)

{

         GPIO_InitTypeDef GPIO_InitStructure;

         RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);                        

         RCC_APB1PeriphClockCmd(RCC_APB1Periph_DAC, ENABLE);

         GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4;

         GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;

         GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;

         GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

         GPIO_InitStructure.GPIO_OType = GPIO_OType_OD;

         GPIO_Init(GPIOA, &GPIO_InitStructure);     

         DAC_InitTypeDef  DAC_InitStructure;

         DAC_DeInit();

         DAC_InitStructure.DAC_Trigger = DAC_Trigger_Software;

         DAC_InitStructure.DAC_WaveGeneration = DAC_WaveGeneration_None;

         DAC_InitStructure.DAC_OutputBuffer = DAC_OutputBuffer_Enable;

         DAC_Init(DAC_Channel_1, &DAC_InitStructure);

         DAC_Cmd(DAC_Channel_1,ENABLE);

         DAC_SetChannel1Data(DAC_Align_12b_R,0x1fff);

         DAC_SoftwareTriggerCmd(DAC_Channel_1,ENABLE);

}

// The test height of TE-01 ,Unit mm

float test_height;

// Height bias, Unit mm

float bias = 180;

// Analog value output

s16 analog=0;

// Main

void main(void)

{

         // Interrupt Group Configuration

         NVIC_Config();

         // Serial Initialize

         USART1_Init();

         // DAC Config

         DAC_Config();

         // Main Loop

         while(1)

         {

                   // Remove Bias

                   test_height = distance - bias;

                   // Data Conversion, 3V corresponding to the height of 12m, therefore

                   // test_height * 3.3 * 4096/（3 * 1200）= test_height * 4096 / 1320

                   analog = (s16)(test_height*4096/1320);

                   // Range Limit

                   analog = analog < 4095 ? analog : 4095;

                   analog = analog > 0 ? analog : 0;

                   // Voltage Output

                   DAC_SetChannel1Data(DAC_Align_12b_R,analog);

                   DAC_SoftwareTriggerCmd(DAC_Channel_1,ENABLE);

         }

}