STM32StepByStep:Step4 Sensors usage

Using sensors with B-L475E-IOT01A and with B-U585I-IOT02A60min

Target description
The purpose of this tutorial is to explain how to perform measurements with the sensors available in the STM32L4 Discovery kit and in the B-U585I-IOT02A Discovery kit. A step by step configuration of the temperature sensor is available.
After this tutorial, you will be able to collect values using the sensors available on the B-L475E-IOT01A board and on the B-U585I-IOT02A board.
The appendix of this tutorial provides guidelines on how to port an AC6 example to STM32CubeIDE.

Prerequisites
You already followed:

• Step1: Tools installation and first test
  
• Step3: UART and new board introduction
  

Hardware

• STM32L4 Discovery kit IoT node (B-L475E-IOT01A )
  
• B-U585I-IOT02A Discovery kit IoT node (B-U585I-IOT02A )
  
• USB cable Type-A to Micro-B

Literature

• UM2153 Discovery kit for IoT node, multi-channel communication with STM32L4
  
• UM1884 Description of STM32L4/L4+ HAL and low-layer drivers
  
• UM2839 Discovery kit for IoT node with STM32U5 Series
  
• UM2911 Description of STM32U5 HAL and low-layer drivers
  
• UM1859 Getting started with the X-CUBE-MEMS1 motion MEMS and environmental sensor software expansion for STM32Cube
  
• UM2579 Migration guide from System Workbench to STM32CubeIDE
  
• Getting started with STM32L4 Discovery kit IoT node
  
• Discover the new STM32U5 IoT node B-U585-IOT02A Discovery kit
  

1. Using sensors with B-L475E-IOT01A

1.1. Hardware description

The main sensors available in the STM32L4 Discovery kit IoT node (B-L475E-IOT01A) are:

• Capacitive digital sensor for relative humidity and temperature (HTS221)
  
• 260-1260 hPa absolute digital output barometer (LPS22HB)
  
• 3D accelerometer and 3D gyroscope (LSM6DSL)
  
• High-performance 3-axis magnetometer (LIS3MDL).
  

1.2. Example: Getting temperature values using the HTS221 sensor and displaying them on a terminal

The purpose of this section is to provide a step by step description on how to interface with the HTS221 sensor to get temperature values and to display them on a terminal.

1.2.1. Create a working project with STM32CubeMX

The starting point is the project generated with STM32CubeMX, described in the Step3 tutorial : Introduction to the UART I/F on B-L475E-IOT01A.

• Follow the steps in the tutorial.
  
• Name the generated project as L4_IOT_Sensors.
  

1.2.2. Copy BSP drivers to your project

The BSP (board support package) drivers are available in the STM32CubeL4 package. This provides APIs corresponding to the hardware components of a board.

The lastest version of the STM32CubeL4 package is downloaded by default in the STM32CubeMX repository:

C:\Users\user_name\STM32Cube\Repository\STM32Cube_FW_L4_Vx.xx.x.

The image below shows the BSP location and its content:

File:Info.png

In this example, the STM32CubeL4 version used is 1.11.0. Version can increase over time.

Follow these steps to copy the BSP drivers to your project:

• In the generated project, create a folder L4_IOT_Sensors/Drivers/BSP.

• Copy the STM32CubeL4/Drivers/BSP/B-L475E-IOT01 folder and paste it in the L4_IOT_Sensors/Drivers/BSP folder.

• Copy the STM32CubeL4/Drivers/BSP/Components folder and paste it under L4_IOT_Sensors/Drivers/BSP/Components.

• Only the HTS221 temperature sensor is used. For this reason, any other files and folders copied to the working directory can be removed. This step is optional:

    * Keep only the following files under  L4_IOT_Sensors\Drivers\BSP\B-L475E-IOT01:

    * Keep only the following files under L4_IOT_Sensors\Drivers\BSP\Components:

1.2.3. Support BSP in STM32CubeIDE workspace

Added folders appear automatically in the STM32CubeIDE workspace:

1.2.4. Update include paths

Update the paths to support new header files:

• Select the relevant project from the Project Explorer perspective:

• From Project menu or File menu, go to Properties > C/C++ Build > Settings > Tool Settings > MCU GCC Compiler > Include paths.
  
• Click on to include the new paths.
  
• Add ../Drivers/BSP/B-L475E-IOT01 and ../Drivers/BSP/Components/hts221 paths.
  

The following screenshot summarizes the steps to follow:

1.2.5. Update source files

Edit main.c as follows:

• Include the header files: stm32l475e_iot01.h, stm32l475e_iot01_tsensor.h and math.h
  

/* USER CODE BEGIN Includes */
#include "stm32l475e_iot01.h"
#include "stm32l475e_iot01_tsensor.h"
#include <math.h>
/* USER CODE END Includes */

• Add private values. These values are used to display temperature and messages on the terminal:

/* USER CODE BEGIN PV */
/* Private variables -------------------------------------------------------*/
float temp_value = 0;  // Measured temperature value
char str_tmp[100] = ""; // Formatted message to display the temperature value
uint8_t msg1[] = "****** Temperature values measurement ******\n\n\r";
uint8_t msg2[] = "=====> Initialize Temperature sensor HTS221 \r\n";
uint8_t msg3[] = "=====> Temperature sensor HTS221 initialized \r\n ";
/* USER CODE END PV */

• Display messages on the terminal and initialize the HTS221 temperature sensor:

/* USER CODE BEGIN 2 */
HAL_UART_Transmit(&huart1,msg1,sizeof(msg1),1000);
HAL_UART_Transmit(&huart1,msg2,sizeof(msg2),1000);
BSP_TSENSOR_Init();
HAL_UART_Transmit(&huart1,msg3,sizeof(msg3),1000);
/* USER CODE END 2 *//

• In the while (1) loop, read the temperature value, format it, and then display the message with the measured value on the terminal:

/* USER CODE BEGIN 3 */
temp_value = BSP_TSENSOR_ReadTemp();
int tmpInt1 = temp_value;
float tmpFrac = temp_value - tmpInt1;
int tmpInt2 = trunc(tmpFrac * 100);
snprintf(str_tmp,100," TEMPERATURE = %d.%02d\n\r", tmpInt1, tmpInt2);
HAL_UART_Transmit(&huart1,( uint8_t *)str_tmp,sizeof(str_tmp),1000);
HAL_Delay(1000);
/* USER CODE END 3 */

File:Info.png

Updates must only be made on the required USER CODE section, to avoid overwriting all the content with a new STM32CubeMX code generation.

1.2.6. Compile and run the example

• Click on the Build button to compile the project.
  
• Click on the Debug button to run the software.
  
• Open a console emulator such as TeraTerm . To configure the console baud rate, select data bits: 8 and click OK. Port name may differ on your computer.
  
• STM32CubeIDE opens the Debug perspective. Click on the Resume button to execute the code.
  
• TeraTerm displays the initialization message preceding the measured temperature values:
  

Now you are able to:

• Build your own project to measure temperature values using the embedded sensor in B-L475E-IOT01A.
  
• Add BSP components to an STM32CubeMx generated project.
  
• Extend the use of the board to sensors other than HTS221, to make environmental measurements.

2. Using sensors with B-U585-IOT02A

2.1. Hardware description

The main sensors available in B-U585I-IOT02A discovery kit for the IoT node are:

• Capacitive digital sensor for relative humidity and temperature (HTS221)
  
• 260-1260 hPa absolute digital output barometer (LPS22HH)
  
• 3D accelerometer and 3D gyroscope (ISM330DHCX)
  
• High-performance 3-axis magnetometer (IIS2MDCTR).
  

2.2. Example: Getting temperature values using the HTS221 sensor and displaying them on a terminal

The purpose of this section is to provide a step by step description on how to interface with the HTS221 sensor to get temperature values and to display them on a terminal.

2.2.1. Create a working project with STM32CubeMX

Create a new project using STM32CubeMX:

• Select the B-U585I-IOT02A board using the Board selector.
  

• Answer Yes to Initialize all peripherals with their default Mode ? popup.
  

• Select without TrustZone activated?. Answer OK to the Create a new project without TrustZone activated? popup.
  

• Verify in the Pinout tab that the USART1 mode is configured to Asynchronous.
  

• Click on the USART1 button in the Configuration tab. Set Word Length to 8 Bits, baud rate to 115200 Bits/s, Parity to None and Stop Bits to 1, as shown below:
  

• Enable ICache in the Pinout tab by selecting Memory address remap to reach the maximum performance.
  

• Switch to the Project Manager tab: Select STM32CubeIDE as Toolchain/IDE and name your project.
  

• Click on Generate Code.

• Accept to open the project in STM32CubeIDE and follow the steps.

• Call the generated project U5_IOT_Sensors.
  

2.2.2. Copy BSP drivers to your project

The BSP (board support package) drivers are available in the STM32CubeU5 package. This provides APIs corresponding to the hardware components of a board.

The lastest version of the STM32CubeU5 package is downloaded by default in the SMT32CubeMX repository:

C:\Users\user_name\STM32Cube\Repository\STM32Cube_FW_U5_Vx.xx.x.

The image below shows the BSP location and its content:

File:Info.png

In this example, the STM32CubeU5 version used is 1.1.1. Version can increase over time.

Here are the steps to follow in order to copy the BSP drivers to your project:

• In the generated project, create a folder U5_IOT_Sensors/Drivers/BSP.

• Copy the STM32CubeU5/Drivers/BSP/B-U585-IOT02 folder and paste it to the U5_IOT_Sensors/Drivers/BSP folder.
  

• Copy the STM32CubeU5/Drivers/BSP/Components folder and paste it under U5_IOT_Sensors/Drivers/BSP/Components.
  

• Only the HTS221 temperature sensor is used. For this reason, any other files and folders copied to the working directory can be removed. This step is optional:
  

    * Keep only the following folders under U5_IOT_Sensors\Drivers\BSP\Components:

    *Keep only the following folders under  U5_IOT_Sensors\Drivers\BSP\B-U585-IOT02:

• Rename the file b_u585i_iot02a_conf_template.h to b_u585i_iot02a_conf.h.
  

2.2.3. Support BSP in STM32CubeIDE workspace

Added folders appear automatically in the STM32CubeIDE workspace:

2.2.4. Update include paths

Update the paths to support new header files:

• Select the relevant project from the Project Explorer perspective:

• From Project menu or File menu, go to Properties > C/C++ Build > Settings > Tool Settings > MCU GCC Compiler > Include paths.
  
• Click on to include the new paths.
  
• Add the paths ../Drivers/BSP/B-U585I-IOT02A , ../Drivers/BSP/Components/hts221 and ../Drivers/BSP/Components/lps22hh
  

The following screenshot summarizes the steps to follow:

2.2.5. Update source files

Edit main.c as follows:

• Include the header files: b_u585i_iot02a.h, b_u585i_iot02a_env_sensors.h and math.h
  

/* USER CODE BEGIN Includes */
#include "b_u585i_iot02a.h"
#include "b_u585i_iot02a_env_sensors.h"
#include <math.h>
/* USER CODE END Includes */

• Add private values. These values are used to display temperature and messages on the terminal:

/* USER CODE BEGIN PV */
/* Private variables -------------------------------------------------------*/
float temp_value = 0;  // Measured temperature value
char str_tmp[100] = ""; // Formatted message to display the temperature value
uint8_t msg1[] = "****** Temperature values measurement ******\n\n\r";
uint8_t msg2[] = "=====> Initialize Temperature sensor HTS221 \r\n";
uint8_t msg3[] = "=====> Temperature sensor HTS221 initialized \r\n";
/* USER CODE END PV */

• Display messages on the terminal and initialize the HTS221 temperature sensor:

/* USER CODE BEGIN 2 */
HAL_UART_Transmit(&huart1,msg1,sizeof(msg1),1000);
HAL_UART_Transmit(&huart1,msg2,sizeof(msg2),1000);
BSP_ENV_SENSOR_Init(0, ENV_TEMPERATURE);
BSP_ENV_SENSOR_Enable(0, ENV_TEMPERATURE);
HAL_UART_Transmit(&huart1,msg3,sizeof(msg3),1000);
/* USER CODE END 2 *//

• In the while (1) loop, read the temperature value, format it, and then display the message with the measured value on the terminal:

/* USER CODE BEGIN 3 */
BSP_ENV_SENSOR_GetValue(0, ENV_TEMPERATURE, &temp_value);
int tmpInt1 = temp_value;
float tmpFrac = temp_value - tmpInt1;
int tmpInt2 = trunc(tmpFrac * 100);
snprintf(str_tmp,100," TEMPERATURE = %d.%02d\n\r", tmpInt1, tmpInt2);
HAL_UART_Transmit(&huart1,( uint8_t *)str_tmp,sizeof(str_tmp),1000);
HAL_Delay(1000);
/* USER CODE END 3 */

File:Info.png

Updates must only be made on the required USER CODE section, to avoid overwriting all the content with a new STM32CubeMX code generation.

2.2.6. Compile and run the example

• Click on the Build button to compile the project.
  
• Click on the Debug button to run the software.
  
• Open a console emulator such as TeraTerm . To configure the console baud rate, select data bits: 8 and click OK. Port name may differ on your computer.
  
• STM32CubeIDE opens the Debug perspective. Click on the Resume button to execute the code.
  
• TeraTerm displays the initialization message preceding the measured temperature values:
  

Now you are able to:

• Build your own project to measure temperature values using the embedded sensor in B-U585I-IOT02A.
  
• Add BSP components to an STM32CubeMx generated project.
  
• Extend the use of the board to sensors other than HTS221, to make environmental measurements.

3. Appendix: Porting an AC6 example to STM32CubeIDE

DataLogTerminal is the example used in this appendix. It is located in: STM32CubeExpansion_MEMS1_V7.1.0\Projects\STM32L476RG-Nucleo\Examples\IKS01A2\DataLogTerminal

File:Info.png

STM32CubeExpansion_MEMS1_V7.1.0 is the extract of X-CUBE-MEMS. More recent versions of this package may be available over time from the same link.

In order to prevent future compilation errors due to long paths, it is recommended to place the package under C:.

3.1. Hardware description

The X-NUCLEO-IKS01A2 is a motion MEMS and environmental sensor expansion board for the STM32 64-pin Nucleo. It interfaces with NUCLEO-L476RG via I²C-bus pins.

3.2. Example: Getting temperature values using the HTS221 sensor and displaying them on a terminal (Porting from AC6 to STM32CubeIDE)

The purpose of this section is to provide a step by step description on how to interface the X-NUCLEO IKS01A2 HTS221 sensor and the NUCLEO-L476RG board in order to obtain temperature values and to display them on a terminal.

3.2.1. Hardware setup

• Extend your Nucleo board with the X-NUCLEO-IKS01A2 shield using the Arduino connectors.
  
• Connect the board with its shield to your computer.
  

3.2.2. Example details

A description of the DataLogTerminal example is available under STM32CubeExpansion_MEMS1_ V7.1.0\Projects\STM32L476RG-Nucleo\Examples\IKS01A2\DataLogTerminal, in the readme.txt file:

@par Example Description
Main function is to show how to use sensor expansion board to send sensor data from a Nucleo board using UART to a connected PC or desktop, and display it on generic applications like TeraTerm.
After connection has been established:
- The user can view the data from various on-board environment sensors such as temperature, humidity, and pressure
- The user can also view data from various on-board MEMS sensors such as accelerometer, gyroscope, and magnetometer.

3.2.3. Porting the example to STM32CubeIDE

Import the DataLogTerminal example based on SW4STM32 and dedicated to the NUCLEO-L476RG into STM32CubeIDE: STM32CubeExpansion_MEMS1_V7.1.0\Projects\STM32L476RG-Nucleo\Examples\IKS01A2\DataLogTerminal

The project must be converted and the following message is displayed:

• When clicking on OK, the following message pops up:

• Click OK.

• Select the relevant project from the Project Explorer perspective:

3.2.4. Compiling and running the example

• Click on the Build button to compile the project.
  
• Click on the Debug arrow and select Debug Configurations'.
  
• In the Debug Configuration window that pops up, make sure that the selected Debug probe is ST-LINK:

• From the same window, click on Debug, or click on the Debug button to run the software.
  
• Open a console emulator such as TeraTerm . Configure the Console baud rate, select Data bits: 8 and click OK. The port name may differ on your computer.
  
• Click on the Resume button to execute the code. TeraTerm displays the measured values using the sensors available in the shield X-NUCLEO-IKS01A2.
  
• The values measured by the X-NUCLEO-IKS01A2 sensors are displayed in the TeraTerm window as follows:

4. References

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