Firmware Power Optimization for a Zephyr-based BLE Audio Product

Project Overview

An existing battery-powered wireless audio transmitter built on the Nordic nRF5340 SoC and Zephyr RTOS delivered reliable BLE Audio functionality but fell short on battery performance, offering only 4–5 hours of runtime. With the hardware already finalized, extending battery life to the target of 8+ hours required a firmware-only optimization strategy. The challenge was to reduce power consumption without compromising BLE Audio stability, streaming quality, or system responsiveness. Below are some client requirements:

Extend Battery Life Without Hardware Changes

Achieve 8+ hours of continuous BLE Audio playback using firmware-only optimization on the fixed nRF5340 hardware.

Maintain High-Quality BLE Audio Performance

Preserve stable BLE Audio streaming, low latency, and connection reliability while significantly reducing power consumption.

Optimize Zephyr RTOS Firmware for Efficiency

Eliminate power-heavy firmware behaviors, fine-tune power states, and ensure all peripherals and radio operations run at peak efficiency.

Business Challenges

A 4- to 5-hour battery life reduced the product's worth. The task was obvious after the hardware was fixed: maintain dependable BLE, reduce battery drain, and improve firmware efficiency.

Limited Battery Performance

Short battery life reduced product competitiveness and user satisfaction, requiring urgent improvement.

No Hardware Modification Scope

With hardware already finalized, all optimizations had to be achieved through firmware enhancements alone.

Firmware Power Inefficiencies

Firmware inefficiencies affecting power consumption needed to be identified, measured, and eliminated.

Power Savings Without BLE Impact

BLE Audio performance had to remain stable and reliable while significantly cutting power usage.

Zephyr & nRF5340 Constraints

All improvements had to fit within Zephyr RTOS constraints and Nordic nRF5340 hardware capabilities.

Silicon Signals’ Solution

Partnering with the client, Silicon Signals optimized the Zephyr RTOS firmware, adjusting power management, BLE settings, and threads to double battery life and preserve clear audio.

Power

Enabled and fine-tuned Zephyr’s system and runtime power management.

Sync

Replaced busy-wait loops with semaphore-based thread synchronization.

Peripherals

Explicitly suspended idle peripherals like debug UART and I2S.

BLE

Tuned connection interval, latency, and supervision timeout to cut radio use.

Clocks

Managed HFCLK carefully, releasing it when not required.

Logging

Reduced verbosity to prevent unnecessary CPU wakeups.

Engineering Facts That Matter

Our effectiveness, customer satisfaction, and track record of success serve as indicators of the value we provide.

Extended Battery Life Achieved

0 + hours

Idle Power Consumption Reduced

40- 41 %

Lower Active Streaming Power

25- 26 %

Let’s develop the right solution for your business.

Results You Can Count On

Tech Stack

SoC

Nordic nRF5340

Power Profiling Tool

Nordic Power Profiler Kit II (PPK2)

Bluetooth Protocol

Bluetooth Low Energy (BLE) Audio profile

RTOS

Zephyr OS (latest stable version)

Development Language

C (Zephyr kernel and application code)

Build System

Zephyr SDK / CMake / west CLI

Proven Outcomes

Stronger planning results, increased customer satisfaction, and operational improvements.

40–50% Lower Idle Power

Significantly reduced background current draw through optimized PM and peripheral control.

2x Battery Life Improvement

Battery extended from ~4.5 hours to 9+ hours without any hardware modifications.

25–35% Lower Active Power

Improved streaming efficiency with better BLE tuning, clock control, and CPU sleep behavior.

Stable, Reliable BLE Audio

Maintained seamless audio quality with fewer CPU wake-ups and improved firmware responsiveness.

Let’s build smarter, longer-lasting BLE Audio systems together

If you're ready to create an ultra-efficient, low-power, real-time BLE Audio product, this case study shows what’s possible when firmware excellence meets engineering innovation.