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In this tutorial you will learn how to use a Lidar sensor with Nucleo-64. I am using Interrupts to get the data from uart.
So, let's get started!
Lidar works at a baud rate of 115200 as indicated in the datasheet
Settings for Lidar
The data frame consist of 8 bytes with byte 0 and 1 as header.which could be used to sync the data.
Data Format from Lidar
The image below is showing the wiring in the tfmini lidar.As we are using UART protocol do not worry about SCL and SDA lines(SPI communication).
Pin connection
We are using UART3 which corresponds to pin PB11(Receiver) and PB10(Transmitter) as shown in the picture below.
Pin Out
Connection
/* USER CODE BEGIN Header */
/**
******************************************************************************
* @file : main.c
* @brief : Main program body
* @Author :Divesh Dutt
*
* @Description:The main program gets data from UART2 of nucleo64 and displays the Hex data
* to VCP(virtual port).I am using UART3 to connect Lidar to nucleo board.
* In more advance scenario a graphical frontend could be used to add additional features.
******************************************************************************
* @attention
*
* <h2><center>© Copyright (c) 2021 STMicroelectronics.
* All rights reserved.</center></h2>
*
* This software component is licensed by ST under BSD 3-Clause license,
* the "License"; You may not use this file except in compliance with the
* License. You may obtain a copy of the License at:
* opensource.org/licenses/BSD-3-Clause
*
******************************************************************************
*/
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include<stdlib.h>
#include<stdio.h>
#include<string.h>
#define HEX_CONVERSION
/* USER CODE END Includes */
/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */
/* USER CODE END PTD */
/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */
/* USER CODE END PD */
/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */
/* USER CODE END PM */
/* Private variables ---------------------------------------------------------*/
UART_HandleTypeDef huart2;
UART_HandleTypeDef huart3;
/* USER CODE BEGIN PV */
//uint8_t index;
volatile uint8_t rxBuffer[9]; //variable to receive data from lidar
volatile uint8_t txBuffer[9]; //store to converted Hex data from rxBuffer
volatile uint8_t quotient[9];
volatile uint8_t temp[9];
uint8_t FrameReceive[9];
uint16_t distance;
uint8_t offset=120;
uint8_t scaling=10;
uint8_t strlimit=10;
volatile char recdflag; //used to disable conversion while transfer in process
/* USER CODE END PV */
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_USART2_UART_Init(void);
static void MX_USART3_UART_Init(void);
/* USER CODE BEGIN PFP */
uint8_t Checksum(uint8_t *data, uint8_t length); //check the checksum of incoming frame
void string2hexString(char* input, char* output);
/* USER CODE END PFP */
/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
/* USER CODE END 0 */
/**
* @brief The application entry point.
* @retval int
*/
int main(void)
{
/* USER CODE BEGIN 1 */
// int len,j,loop;
/* USER CODE END 1 */
/* MCU Configuration--------------------------------------------------------*/
/* Reset of all peripherals, Initializes the Flash interface and the Systick. */
HAL_Init();
/* USER CODE BEGIN Init */
/* USER CODE END Init */
/* Configure the system clock */
SystemClock_Config();
/* USER CODE BEGIN SysInit */
/* USER CODE END SysInit */
/* Initialize all configured peripherals */
MX_GPIO_Init();
MX_USART2_UART_Init();
MX_USART3_UART_Init();
/* USER CODE BEGIN 2 */
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
HAL_UART_Receive_IT(&huart3,(uint8_t *)rxBuffer,sizeof(rxBuffer));
if(recdflag)
{
recdflag=0;
for(int i = 0 ; i < 9 ; i++)
{
#ifdef HEX_CONVERSION
quotient[i]=rxBuffer[i];
while(quotient[i]!=0)
{
temp[i]=quotient[i]%16;
if(temp[i]<10)
{
temp[i]=temp[i]+48;
}
else
{
temp[i]=temp[i]+55;
}
txBuffer[i]=temp[i];
quotient[i]=quotient[i]/16;
}
#else
sprintf((char*)(txBuffer+i),"%02X", rxBuffer[i]);
#endif
}
HAL_UART_Transmit(&huart2,(uint8_t *)&txBuffer, sizeof(txBuffer),100);
HAL_Delay(1000);
HAL_UART_Receive_IT(&huart3,(uint8_t *)&rxBuffer, sizeof(rxBuffer));
}
#if 0
if(recdflag)
{
recdflag=0;
if((rxBuffer=='Y')&&(index==0))
{
FrameReceive[index]=rxBuffer;
index++;
}
else
{
if(FrameReceive[0]=='Y')
{
if(index<8)
{
FrameReceive[index]=rxBuffer;
index++;
}
else
{
FrameReceive[index]=rxBuffer;
if(FrameReceive[1]=='Y')
{
if(Checksum(FrameReceive,8))
{
distance= (uint16_t)(((FrameReceive[2] + (FrameReceive[3]*256))+offset)/scaling);
}
}
for(uint8_t i=0;i<8;i++)
{
FrameReceive[i]=0;
}
index=0;
}
}
}
}
/* USER CODE BEGIN 3 */
/* USER CODE END 3 */
#endif
/* USER CODE END WHILE */
/* USER CODE BEGIN 3 */
/* USER CODE END 3 */
}
}
/**
* @brief System Clock Configuration
* @retval None
*/
void SystemClock_Config(void)
{
RCC_OscInitTypeDef RCC_OscInitStruct = {0};
RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};
/** Initializes the RCC Oscillators according to the specified parameters
* in the RCC_OscInitTypeDef structure.
*/
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
RCC_OscInitStruct.HSIState = RCC_HSI_ON;
RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9;
RCC_OscInitStruct.PLL.PREDIV = RCC_PREDIV_DIV1;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
Error_Handler();
}
/** Initializes the CPU, AHB and APB buses clocks
*/
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
|RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
{
Error_Handler();
}
PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_USART2|RCC_PERIPHCLK_USART3;
PeriphClkInit.Usart2ClockSelection = RCC_USART2CLKSOURCE_PCLK1;
PeriphClkInit.Usart3ClockSelection = RCC_USART3CLKSOURCE_PCLK1;
if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
{
Error_Handler();
}
}
/**
* @brief USART2 Initialization Function
* @param None
* @retval None
*/
static void MX_USART2_UART_Init(void)
{
/* USER CODE BEGIN USART2_Init 0 */
/* USER CODE END USART2_Init 0 */
/* USER CODE BEGIN USART2_Init 1 */
/* USER CODE END USART2_Init 1 */
huart2.Instance = USART2;
huart2.Init.BaudRate = 9600;
huart2.Init.WordLength = UART_WORDLENGTH_8B;
huart2.Init.StopBits = UART_STOPBITS_1;
huart2.Init.Parity = UART_PARITY_NONE;
huart2.Init.Mode = UART_MODE_TX_RX;
huart2.Init.HwFlowCtl = UART_HWCONTROL_NONE;
huart2.Init.OverSampling = UART_OVERSAMPLING_16;
huart2.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
huart2.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
if (HAL_UART_Init(&huart2) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN USART2_Init 2 */
/* USER CODE END USART2_Init 2 */
}
/**
* @brief USART3 Initialization Function
* @param None
* @retval None
*/
static void MX_USART3_UART_Init(void)
{
/* USER CODE BEGIN USART3_Init 0 */
/* USER CODE END USART3_Init 0 */
/* USER CODE BEGIN USART3_Init 1 */
/* USER CODE END USART3_Init 1 */
huart3.Instance = USART3;
huart3.Init.BaudRate = 115200;
huart3.Init.WordLength = UART_WORDLENGTH_8B;
huart3.Init.StopBits = UART_STOPBITS_1;
huart3.Init.Parity = UART_PARITY_NONE;
huart3.Init.Mode = UART_MODE_TX_RX;
huart3.Init.HwFlowCtl = UART_HWCONTROL_NONE;
huart3.Init.OverSampling = UART_OVERSAMPLING_16;
huart3.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
huart3.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
if (HAL_UART_Init(&huart3) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN USART3_Init 2 */
/* USER CODE END USART3_Init 2 */
}
/**
* @brief GPIO Initialization Function
* @param None
* @retval None
*/
static void MX_GPIO_Init(void)
{
GPIO_InitTypeDef GPIO_InitStruct = {0};
/* GPIO Ports Clock Enable */
__HAL_RCC_GPIOC_CLK_ENABLE();
__HAL_RCC_GPIOF_CLK_ENABLE();
__HAL_RCC_GPIOA_CLK_ENABLE();
__HAL_RCC_GPIOB_CLK_ENABLE();
/*Configure GPIO pin Output Level */
HAL_GPIO_WritePin(LD2_GPIO_Port, LD2_Pin, GPIO_PIN_RESET);
/*Configure GPIO pin : B1_Pin */
GPIO_InitStruct.Pin = B1_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_IT_FALLING;
GPIO_InitStruct.Pull = GPIO_NOPULL;
HAL_GPIO_Init(B1_GPIO_Port, &GPIO_InitStruct);
/*Configure GPIO pin : LD2_Pin */
GPIO_InitStruct.Pin = LD2_Pin;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(LD2_GPIO_Port, &GPIO_InitStruct);
}
/* USER CODE BEGIN 4 */
//#if 0
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
recdflag = 1;
}
//Checksum is the sum of the first 8 bytes of actual data Checksum = Byte1 + Byte2 + ... + Byte8
uint8_t Checksum(uint8_t *data, uint8_t length)
{
uint16_t count;
uint16_t Sum = 0;
for (count = 0; count < length; count++)
Sum = Sum + data[count];
return (Sum);
}
//function to convert ascii char[] to hex-string (char[])
void string2hexString(char* input, char* output)
{
int loop;
int i;
i=0;
loop=0;
while(input[loop] != '\0')
{
sprintf((char*)(output+i),"%02X", input[loop]);
loop+=1;
i+=2;
}
//insert NULL at the end of the output string
output[i++] = '\0';
}
/* USER CODE END 4 */
/**
* @brief This function is executed in case of error occurrence.
* @retval None
*/
void Error_Handler(void)
{
/* USER CODE BEGIN Error_Handler_Debug */
/* User can add his own implementation to report the HAL error return state */
__disable_irq();
while (1)
{
}
/* USER CODE END Error_Handler_Debug */
}
#ifdef USE_FULL_ASSERT
/**
* @brief Reports the name of the source file and the source line number
* where the assert_param error has occurred.
* @param file: pointer to the source file name
* @param line: assert_param error line source number
* @retval None
*/
void assert_failed(uint8_t *file, uint32_t line)
{
/* USER CODE BEGIN 6 */
/* User can add his own implementation to report the file name and line number,
ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
/* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
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