The MotionPW library expands the functionality of the
X-CUBE-MEMS1 software by acquiring data from the accelerometer to
provide information about the number of steps and cadence performed
with the wearable device.

Compatibility

The library is designed for ST MEMS sensors only. Using other
MEMS sensors may result in different functionality and
performance.

Implementation

A sample implementation is available for X-NUCLEO-IKS4A1 and
X-NUCLEO-IKS01A3 expansion boards mounted on specified development
boards.

Technical Information

For detailed functions and parameters of the MotionPW APIs,
refer to the MotionPW_Package.chm compiled HTML file located in the
Documentation folder.

APIs

MotionPW_GetLibVersion(char *version)
MotionPW_Initialize(void)

MotionPW_Update(MPW_input_t *data_in, MPW_output_t
*data_out)
MotionPW_ResetPedometerLibrary(void)

MotionPW_ResetStepCount(void)
MotionPW_UpdateEnergyThreshold(float *energy_threshold)

Frequently Asked Questions (FAQ)

Q: Can I use MotionPW library with non-ST MEMS sensors?

A: The library is designed for ST MEMS sensors only.
Compatibility with other MEMS sensors is not guaranteed.

Q: What is the required accelerometer data sampling
frequency?

A: The required sampling frequency is 50 Hz for accurate
detection of steps and cadence.

Q: How do I initialize the MotionPW library?

A: Call the MotionPW_Initialize() function before using the
fitness activity library. Ensure the CRC module in the STM32
microcontroller is enabled.

“`

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UM2350
User manual
Getting started with MotionPW real-time pedometer for wrist library in X-CUBEMEMS1 expansion for STM32Cube
Introduction
The MotionPW middleware library is part of the X-CUBE-MEMS1 software and runs on STM32 Nucleo. It provides real-time information about the number of steps and cadence which the user just performed with the wearable device (e.g. a smart watch). This library is intended to work with ST MEMS only. The algorithm is provided in static library format and is designed to be used on STM32 microcontrollers based on the ARM® Cortex®-M3, ARM Cortex®-M33, ARM® Cortex®-M4, ARM® Cortex®-M7 architecture. It is built on top of STM32Cube software technology to ease portability across different STM32 microcontrollers. The software comes with sample implementation running on X-NUCLEO-IKS4A1 or X-NUCLEO-IKS01A3 expansion board on a NUCLEO-F401RE, NUCLEO-U575ZI-Q or NUCLEO-L152RE development board.

UM2350 – Rev 4 – May 2025 For further information, contact your local STMicroelectronics sales office.

www.st.com

UM2350
Acronyms and abbreviations

Acronyms and abbreviations

Acronym API BSP GUI HAL IDE

Table 1. List of acronyms

Application programming interface Board support package Graphical user interface Hardware abstraction layer Integrated development environment

Description

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2
2.1 2.2
2.2.1
2.2.2
Note:

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MotionPW middleware library in X-CUBE-MEMS1 software expansion for STM32Cube

MotionPW middleware library in X-CUBE-MEMS1 software expansion for STM32Cube

MotionPW overview
The MotionPW library expands the functionality of the X-CUBE-MEMS1 software.
The library acquires data from the accelerometer and provides information about the number of steps and cadence the user just performed with the wearable device.
The library is designed for ST MEMS only. Functionality and performance when using other MEMS sensors are not analyzed and can be significantly different from what described in the document.
A sample implementation is available for X-NUCLEO-IKS4A1 and X-NUCLEO-IKS01A3 expansion boards, mounted on aNUCLEO-F401RE, NUCLEO-U575ZI-Q or NUCLEO-L152RE development board.

MotionPW library
Technical information fully describing the functions and parameters of the MotionPW APIs can be found in the MotionPW_Package.chm compiled HTML file located in the Documentation folder.

MotionPW library description

The MotionPW pedometer library manages the data acquired from the accelerometer; it features:

possibility of detecting the number of steps, cadence and confidence

recognition based on accelerometer data only

required accelerometer data sampling frequency of 50 Hz

resources requirements:

Cortex-M3: 3.7 kB of code and 1.8 kB of data memory

Cortex-M33: 3.5 kB of code and 1.8 kB of data memory

Cortex-M4: 3.5 kB of code and 1.8 kB of data memory

Cortex-M7: 3.6 kB of code and 1.8 kB of data memory

available for ARM® Cortex®-M3, ARM® Cortex®-M33, ARM® Cortex®-M4 and ARM® Cortex®-M7

architectures

MotionPW APIs

The MotionPW library APIs are:

uint8_t MotionPW_GetLibVersion(char *version)

retrieves the library version

*version is a pointer to an array of 35 characters

returns the number of characters in the version string

void MotionPW_Initialize(void)

performs MotionPW library initialization and setup of the internal mechanism including the dynamic memory allocation

This function must be called before using the fitness activity library and the CRC module in the STM32 microcontroller (in RCC peripheral clock enable register) has to be enabled.

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MotionPW middleware library in X-CUBE-MEMS1 software expansion for STM32Cube

void MotionPW_Update(MPW_input_t *data_in, MPW_output_t *data_out)

executes pedometer for wrist algorithm

*data_in parameter is a pointer to a structure with input data

the parameters for the structure type MPW_input_t are:

AccX is the accelerometer sensor value in X axis in g

AccY is the accelerometer sensor value in Y axis in g

AccZ is the accelerometer sensor value in Z axis in g

CurrentActivity is the enumerated input type MPW_activity_t with the following values:

MPW_UNKNOWN_ACTIVITY = 0x00

MPW_WALKING = 0x01

MPW_FASTWALKING = 0x02

MPW_JOGGING = 0x03

*data_out parameter is a pointer to a structure with output data

the parameters for the structure type MPW_output_t are:

Nsteps is number of steps performed by user

Cadence is the cadence of user steps

Confidence is the confidence of calculated output parameter

void MotionPW_ResetPedometerLibrary(void)

resets the library internal variables and mechanism into default values (including current step count)

void MotionPW_ResetStepCount(void)

resets the current step count

void MotionPW_UpdateEnergyThreshold(float *energy_threshold)

updated energy threshold to fine tune step detection algorithm

*energy_threshold parameter is a pointer to energy threshold value

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2.2.3

API flow chart

UM2350
MotionPW middleware library in X-CUBE-MEMS1 software expansion for STM32Cube
Figure 1. MotionPW API logic sequence
Start
Initialize
GetLibVersion
Wait Expiring Timer Data Read Interrupt

Read Accelerometer Data Update
Get Outputs

2.2.4

Demo code The following demonstration code example reads data from the accelerometer sensor, obtains the current activity from MotionAW library and gets the number of steps, cadence and confidence from MotionPW library.
[…] #define VERSION_STR_LENG 35 […] /* Initialization */ char lib_version[VERSION_STR_LENG];
/* Pedometer API initialization function */ MotionPW_Initialize();
/* Activity recognition API initialization function */ MotionAW_Initialize();
/* Optional: Get version */ MotionPW_GetLibVersion(lib_version);
[…] /* Using Pedometer for wrist algorithm */ Timer_OR_DataRate_Interrupt_Handler() {
MPW_input_t MPW_data_in; MPW_output_t MPW_data_out;

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2.2.5

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MotionPW middleware library in X-CUBE-MEMS1 software expansion for STM32Cube
MAW_input_t MAW_data_in; MAW_output_t MAW_data_out;
/* Get acceleration X/Y/Z in g */ MEMS_Read_AccValue(&MAW_data_in.Acc_X, &MAW_data_in.Acc_Y, &MAW_data_in.Acc_Z);
/* Get current activity */ MotionAW_Update(&MAW_data_in, &MAW_data_out, Timestamp);
MPW_data_in.Acc_X = MAW_data_in.Acc_X; MPW_data_in.Acc_Y = MAW_data_in.Acc_Y; MPW_data_in.Acc_Z = MAW_data_in.Acc_Z;
if (MAW_data_out.current_activity == MAW_WALKING) {
MPW_data_in.currentActivity = MPW_WALKING; } else if (MAW_data_out.current_activity == MAW_FASTWALKING) {
MPW_data_in.currentActivity = MPW_FASTWALKING; } else if (MAW_data_out.current_activity == MAW_JOGGING) {
MPW_data_in.currentActivity = MPW_JOGGING; } else {
MPW_data_in.currentActivity = MPW_UNKNOWN_ACTIVITY; }
/* Run pedometer for wrist algorithm */ MotionPW_Update(&MPW_data_in, &MPW_data_out); }
Algorithm performance The pedometer for wrist algorithm uses data from the accelerometer only and runs at a low frequency (50 Hz) to reduce power consumption. When replicating fitness activity with the STM32 Nucleo board, ensure the board is oriented perpendicularly to the forearm, to simulate the wristband position.
Figure 2. Orientation system for wrist-worn devices

Table 2. Algorithm elapse time (µs) Cortex-M4, Cortex-M3

Cortex-M4 STM32F401RE at 84 MHz

Min

Avg

Max

616

Cortex-M3 STM32L152RE at 32 MHz

Min

Avg

Max

296

390

3314

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MotionPW middleware library in X-CUBE-MEMS1 software expansion for STM32Cube

Table 3. Algorithm elapse time (µs) Cortex-M33 and Cortex-M7

Cortex- M33 STM32U575ZI-Q at 160 MHz

Min

Avg

Max

359

Cortex- M7 STM32F767ZI at 96 MHz

Min

Avg

Max

1301

2.3

Sample application

The MotionPW middleware can be easily manipulated to build user applications.

A sample application is provided in the Application folder. It is designed to run on a NUCLEO-F401RE, NUCLEOU575ZI-Q or NUCLEO-L152RE development board connected to an X-NUCLEO-IKS4A1 or X-NUCLEO-IKS01A3 expansion board.

The application recognizes the steps, cadence and confidence in real-time. The data can be displayed through a GUI.

Figure 3. STM32 Nucleo: LEDs, button, jumper

The above figure shows the user button B1 and the three LEDs of the NUCLEO-F401RE board. Once the board is powered, LED LD3 (PWR) turns ON.
A USB cable connection is required to monitor real-time data. The board is powered by the PC via USB connection. This working mode allows the user to display detected steps, cadence and confidence, accelerometer data, time stamp and eventually other sensor data, in real-time, using the MEMS-Studio.

2.4

MEMS Studio application

The sample application uses MEMS-Studio application, which can be downloaded from www.st.com.

Step 1. Ensure that the necessary drivers are installed and the STM32 Nucleo board with appropriate expansion board is connected to the PC.

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MotionPW middleware library in X-CUBE-MEMS1 software expansion for STM32Cube

Step 2.

Launch the MEMS-Studio application to open the main application window.
If an STM32 Nucleo board with supported firmware is connected to the PC, it is automatically detected. Press the [Connect] button to establish connection to the evaluation board.

Figure 4. MEMS-Studio – Connect

Step 3. When connected to a STM32 Nucleo board with supported firmware [Library Evaluation] tab is opened.

To start and stop data streaming, toggle the appropriate [Start] vertical tool bar.

or [Stop] button on the outer

The data coming from the connected sensor can be viewed selecting the [Data Table] tab on the inner vertical tool bar.

Figure 5. MEMS-Studio – Library Evaluation – Data Table

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MotionPW middleware library in X-CUBE-MEMS1 software expansion for STM32Cube
Step 4. Click on the [Pedometer] to open the dedicated application window. Figure 6. MEMS-Studio – Library Evaluation – Pedometer

Step 5.

Click on the [Save To File] to open the dataloging configuration window. Select the sensor and pedometer data to be saved in the file. You can start or stop saving by clicking on the corresponding
button.

Figure 7. MEMS-Studio – Library Evaluation – Save To File

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MotionPW middleware library in X-CUBE-MEMS1 software expansion for STM32Cube

Step 6.

Data Injection mode can be used to send the previously acquired data to the library and receive the
result. Select the [Data Injection] tab on the vertical tool bar to open the dedicated view for this functionality.

Figure 8. MEMS-Studio – Library Evaluation – Data Injection

Step 7.

Click on the [Browse] button to select the file with the previously captured data in CSV format. The data will be loaded into the table in the current view. Other buttons will become active. You can click on:
[Offline Mode] button to switch the firmware offline mode on/off (mode utilizing the previously captured data).
[Start]/[Stop]/[Step]/[Repeat] buttons to control the data feed from MEMS-Studio to the library.

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UM2350
References

References

All of the following resources are freely available on www.st.com. 1. UM1859: Getting started with the X-CUBE-MEMS1 motion MEMS and environmental sensor software
expansion for STM32Cube 2. UM1724: STM32 Nucleo-64 boards (MB1136) 3. UM3233: Getting started with MEMS-Studio

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UM2350

Revision history

Table 4. Document revision history

Date

Version Changes

24-Jan-2018 1 Initial release.

21-Mar-2018 2 Updated Introduction and Section 2.1 MotionPW overview. Updated Section 2.2.5: Algorithm performance and Figure 3. STM32 Nucleo: LEDs, button, jumper.
20-Feb-2019 3 Added X-NUCLEO-IKS01A3 expansion board compatibility information.

Updated Section Introduction, Section 2.1: MotionPW overview, Section 2.2.1: MotionPW library 20-May-2025 4 description, Section 2.2.2: MotionPW APIs, Section 2.2.4: Demo code, Section 2.2.5: Algorithm
performance, Section 2.3: Sample application, Section 2.4: MEMS Studio application

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UM2350
Contents
Contents
1 Acronyms and abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2 MotionPW middleware library in X-CUBE-MEMS1 software expansion for
STM32Cube . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 2.1 MotionPW overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2 MotionPW library . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2.1 MotionPW library description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2.2 MotionPW APIs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2.3 API flow chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2.4 Demo code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2.5 Algorithm performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.3 Sample application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.4 MEMS Studio application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

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UM2350
List of tables

List of tables

Table 1. Table 2. Table 3. Table 4.

List of acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Algorithm elapse time (µs) Cortex-M4, Cortex-M3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Algorithm elapse time (µs) Cortex-M33 and Cortex-M7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

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UM2350
List of figures

List of figures

Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Figure 8.

MotionPW API logic sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Orientation system for wrist-worn devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 STM32 Nucleo: LEDs, button, jumper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 MEMS-Studio – Connect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 MEMS-Studio – Library Evaluation – Data Table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 MEMS-Studio – Library Evaluation – Pedometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 MEMS-Studio – Library Evaluation – Save To File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 MEMS-Studio – Library Evaluation – Data Injection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

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UM2350
IMPORTANT NOTICE READ CAREFULLY STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, enhancements, modifications, and improvements to ST products and/or to this document at any time without notice. Purchasers should obtain the latest relevant information on ST products before placing orders. ST products are sold pursuant to ST’s terms and conditions of sale in place at the time of order acknowledgment. Purchasers are solely responsible for the choice, selection, and use of ST products and ST assumes no liability for application assistance or the design of purchasers’ products. No license, express or implied, to any intellectual property right is granted by ST herein. Resale of ST products with provisions different from the information set forth herein shall void any warranty granted by ST for such product. ST and the ST logo are trademarks of ST. For additional information about ST trademarks, refer to www.st.com/trademarks. All other product or service names are the property of their respective owners. Information in this document supersedes and replaces information previously supplied in any prior versions of this document.
© 2025 STMicroelectronics All rights reserved

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Documents / Resources

ST X-CUBE-MEMS1 Sensor and Motion Algorithm Software Expansion [pdf] User Manual
STM32 Nucleo, X-NUCLEO-IKS4A1, X-NUCLEO-IKS01A3, X-CUBE-MEMS1 Sensor and Motion Algorithm Software Expansion, X-CUBE-MEMS1, Sensor and Motion Algorithm Software Expansion, Motion Algorithm Software Expansion, Algorithm Software Expansion, Software Expansion

References

User Manual

ST X-CUBE-MEMS1 Sensor and Motion Algorithm Software Expansion User Manual

X-CUBE-MEMS1 Sensor and Motion Algorithm Software Expansion

Product Information

Specifications

Product Usage Instructions

Overview

Compatibility

Implementation

Technical Information

APIs

Frequently Asked Questions (FAQ)

Q: Can I use MotionPW library with non-ST MEMS sensors?

Q: What is the required accelerometer data sampling
frequency?

Q: How do I initialize the MotionPW library?

Documents / Resources

References

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