nRF54LM20 BLE Fitness Tracker Firmware
Build a high-end BLE fitness tracker with the nRF54LM20 — the most capable nRF54L chip offering 2MB Flash for rich GATT services, sensor fusion, and OTA DFU with ultra-low standby current.
Why This Combination
The nRF54LM20's 2MB Flash accommodates multiple concurrent GATT services, full accelerometer gesture recognition, and an LE Audio profile — making it the platform for premium fitness wearables.
Protocols & Connectivity
nRF54LM20
The flagship nRF54L series SoC built on a 22nm process, featuring a 128 MHz ARM Cortex-M33 + RISC-V co-processor with 2MB Flash and 512KB RAM — the largest memory in the nRF54L family. Supports Bluetooth LE, Matter, Thread, Zigbee, and 2.4 GHz proprietary protocols up to 4 Mbps. The nRF54LM20A variant adds 66 GPIOs and high-speed USB; the nRF54LM20B adds an integrated Axon NPU for hardware-accelerated Edge AI inference. Security includes TrustZone, CRACEN cryptographic engine with side-channel protection, and tamper detection.
View platformBLE Fitness Tracker
Wearable fitness device that tracks activity, heart rate, and sleep patterns over Bluetooth Low Energy, syncing data to a companion mobile app.
View use caseAll 12 Documents Included
PRD
Comprehensive document defining what your firmware product needs to do — functional requirements, non-functional requirements, power budgets, user stories, and acceptance criteria.
Architecture Doc
High-level system design showing how firmware modules interact — task architecture, communication patterns, memory layout, and dependency maps with Mermaid diagrams.
HAL Doc
Defines the interface layer between your firmware application and hardware peripherals — GPIO, SPI, I2C, UART, ADC drivers with clean API definitions.
State Machine
Formal definition of your firmware's state machine — states, transitions, guards, actions, and error recovery paths visualized with state diagrams.
Context Bundle
Machine-readable JSON file containing all project context — hardware specs, pin mappings, library versions, and configuration — optimized for AI coding tools to consume.
Bootloader/OTA
Complete specification for the device bootloader, firmware update mechanism (DFU), and over-the-air update flow — memory partitioning, image signing, and rollback strategy.
Impl Plan
Phase-by-phase development roadmap breaking the firmware project into sprint-sized work packages with dependencies, milestones, and effort estimates.
HW Config
Detailed pin mappings, peripheral assignments, clock configuration, and power rail definitions for your specific hardware design and development kit.
Libraries/SDK
Reference guide for all software libraries, SDKs, and middleware used in the project — version pinning, initialization sequences, and API usage patterns.
Protocols Doc
Specification of all communication interfaces — BLE services, MQTT topics, REST APIs, UART protocols — with message formats, error handling, and sequence diagrams.
Peripherals
Detailed configuration for each MCU peripheral — ADC settings, timer configurations, DMA channels, interrupt priorities, and power domain assignments.
Code Files
Production-ready starter code files — main.c, CMakeLists.txt, prj.conf, Kconfig, device tree overlays, and .cursorrules — tailored to your specific hardware and project type.
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Learn moreFrequently Asked Questions
Build your nrf54lm20 ble fitness tracker
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