The Hardware Architecture Layer: What Each Generation Provides
nRF52840 — The Proven Foundation
The nRF52840 is a single-core Arm Cortex-M4F running at 64 MHz with 1 MB flash and 256 KB RAM. Its USB 2.0 full-speed integration alongside BLE remains unique in the Nordic lineup and relevant for products requiring USB device enumeration as HID, CDC-ACM, or audio class. Its SoftDevice-based BLE stack (S140) is one of the most battle-tested wireless stacks in embedded production history — millions of deployed units across medical, industrial, and consumer applications.
The platform's limitation is primarily power architecture. In System OFF, the nRF52840 draws approximately 0.7 µA with RAM retention. System ON idle current — the relevant figure for event-driven applications that wake frequently — runs in the 1.5–3 µA range depending on RTC configuration. That's adequate for many applications, but it reflects an architecture designed in 2016.
Ezurio's BL654 module is the production-proven choice from the BL65x family for new designs requiring nRF52840 capability — UART/SPI/I²C interfaces, an on-board antenna, and certification across FCC, IC, CE, and a broad set of country-specific approvals. The BL652 targets space-constrained designs with an external antenna connection.
nRF5340 — Dual-Core and LE Audio
The nRF5340 introduced a dual-core architecture: a 128 MHz Arm Cortex-M33 application core with 1 MB flash and 512 KB RAM, paired with a dedicated 64 MHz Cortex-M33 network core with 256 KB flash and 64 KB RAM. The network core runs the BLE stack in complete isolation from the application processor, communicating via a defined IPC channel.
The practical benefit is determinism. When the application core is executing a sensor fusion algorithm or a TLS handshake, the network core continues servicing BLE connection events without latency introduced by application-layer interrupt competition. For products where BLE connection intervals below 10 ms matter — real-time audio, latency-sensitive control — this architecture eliminates an entire class of stack-tuning problems.
The nRF5340 supports full LE Audio via Nordic's BLE Host stack, including LC3 codec encoding/decoding and broadcast audio streams (Auracast). If your product has any audio transmission requirement — hearing aids, wireless audio accessories, smart speakers — the nRF5340 is the minimum platform. Ezurio's BL5340 module brings these capabilities to a certified, FCC/IC/CE-approved form factor with on-board and U.FL antenna options.
nRF54L15 — The New Power Architecture
The nRF54L15 is architecturally distinct from both predecessors. It runs a 128 MHz Arm Cortex-M33 application core but adds a dedicated low-power PPR (Peripheral Processor) running at 16 MHz that can execute lightweight tasks and monitor I/O without waking the main core. The Global Domain DPLL clock system maintains timing references across power transitions without requiring the CPU to wake for clock management.
The result: System ON active current for the main CPU is approximately 0.5 µA/MHz — roughly half that of the nRF5340 at equivalent clock frequency. System OFF current drops to 0.5 µA with full RAM retention. More relevantly, the PPR subsystem can run active at under 30 µA total, processing sensor data or managing I/O without the main core ever leaving sleep. For coin-cell and energy-harvesting applications, this isn't an incremental improvement — it's a design space expansion.
The nRF54L15 introduces the CRACEN cryptographic engine — a dedicated hardware security module providing AES-128/256, SHA-256/384/512, ECDSA, ECDH, and hardware-accelerated key storage with lifecycle management. This is the foundation for PSA Certified Level 2 and is directly relevant to EU CRA Article 13 requirements for product security attestation. Software-only cryptography on the nRF52840 can meet many of these requirements, but it places the audit burden on your firmware and key management processes rather than on pre-certified silicon.
Ezurio's BL54L15 module is the first module in the BL54Lxx family — bringing BLE 6.0 support, the CRACEN security engine, and sub-microamp always-on operation to a certified, production-ready form factor.
