Smart White Cane - Case Study

For decades, the traditional white cane has been a symbol and a fundamental tool of independence for the blind and visually impaired. While its mechanical design excels at detecting physical obstacles directly ahead, it falls short in the world of modern urban infrastructure.

Once a manufacturer of assistive medical equipment approached us, and the challenge was clear: transform an analog classic into an intelligent device (Smart White Cane) while preserving its lightweight design, reliability, and long battery life.

Smart White Cane Project Context

The client required an intelligent, IoT-enabled assistive device (Smart White Cane) to serve as an extended digital sense for the blind and visually impaired, focusing on energy efficiency, real-time spatial awareness, and intuitive user feedback. The device needed to maintain a continuous, low-power wireless connection with a companion smartphone navigation application, supporting two-way data streaming to transmit ultrasonic sensor telemetry for environmental processing while interpreting incoming GPS navigation cues.

A core requirement was an industrially stable, ultra-low-power firmware architecture built around the STM32WB microcontroller. Specifically, the hardware leverages the dual-core STM32WB5MMG wireless microcontroller, utilizing its internal hardware timers to generate high-precision PWM (Pulse Width Modulation) signals. These signals dynamically modulate haptic vibration levels in the handle for smooth hazard escalation and directional patterns.

Project Context

Start your IoT project today!

Hardware Stack

STM32WB5MMG Wireless Microcontroller

A dual-core SoC with an integrated BLE (Bluetooth Low Energy) radio, enabling low-power wireless communication directly on-chip.

nRF52840-DONGLE

Used as BLE test and validation hardware during development to verify connection stability and two-way data streaming with the companion smartphone application

Firmware Stack

Programming language

BLE (Bluetooth Low Energy) Stack

Manages the low-level radio communication, GATT profiles, and pairing, allowing the microcontroller to securely broadcast and exchange data with the smartphone application.

Hardware PWM Timers (Haptics)

Utilizes dedicated on-chip timers to generate precise pulse-width modulation signals, driving haptic actuators with variable intensity while allowing the main CPU to save power.

STM32Cube (HAL & Wireless Coprocessor Binaries)

Provides the core software framework, including Hardware Abstraction Layer (HAL) drivers and pre-certified BLE binaries for the secondary core, to streamline hardware integration and speed up development.

Schedule a free consultation!

What We Achieved

We developed the firmware for the Smart White Cane prototype based on the dual-core STM32WB microcontroller. By offloading the BLE stack to the dedicated M0+ core, we maintained a stable smartphone connection without interrupting the main application. For navigation and obstacle warnings, we configured hardware timers to generate PWM signals that dynamically modulate haptic vibration intensity based on proximity data and directional cues. To meet the strict battery life requirements, we optimized the overall system power consumption by implementing hardware STOP modes between BLE transmission intervals and ultrasonic sensor readouts, resulting in a fully functional, power-efficient prototype ready for user testing.

Time Estimates

The table below summarizes the time estimates for each development milestone. Given the dual-core architecture of the STM32WB microcontroller, the most significant effort is concentrated in the BLE implementation milestone, where the wireless stack running on the dedicated M0+ core required careful configuration and validation to ensure stable two-way data streaming.

Stage	Min   h	Max   h
BLE implementation (MVF – two-way data streaming)	56	60
PWM & Haptics implementation (Dynamic modulation)	24	30
Ultrasonic Sensor Integration (Telemetry data capture)	12	16
Low-Power Optimization (Sleep modes architecture)	26	36
Total Firmware time	118	142
Point testing and test reporting	18	28
Project Management	54	68
Total project time	190	238

Note: To the final total project estimated time might be added up to 15% of time for risk assessment.