Technical blog
Insights from our daily work: hardware, firmware, software, acoustics, regulatory.
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Cyber Resilience Act: designing compliant connected products
A guide to the Cyber Resilience Act for connected products: classification, requirements, SBOM, supply chain, Article 14 and an embedded worked example.
32 min read -
ISO 9613-2:2024/DAmd 1: the draft amendment takes barrier diffraction back to the 1996 formulas
The draft amendment rewrites Dz and Kmet in Clause 7.4 and restores their 1996 form. How much the numbers move, the two errata in Annexes A and B, and why the third edition already in drafting argues against hard-coding anything.
11 min read -
acmap 0.6.1 and noise-barrier-calc 0.9.3: seven corrections that change the numbers
A code review by a qualified acoustician found seven wrong properties in the engine of both tools: A_bar added on top of the ground effect, K_met given the wrong distance, non-conservative source discretisation, unnormalised spectra.
5 min read -
A local app for forms and reports over the database you already have
Three pillars taken from a commercial product, a deployment model turned upside down: a local app, no cloud and no remote account, where everything derives from a JSON query-spec and a single compiler.
5 min read -
"There is vibration" is not yet a technical question
Disturbance to people, damage to the building, worker exposure, sensitive equipment: four questions with four standards, four quantities and four thresholds. Establishing which one is being asked comes before any measurement.
4 min read -
Designing a room in reverse: RaySound, and what arbitrates the numbers
Why an acoustic simulator that only solves the forward problem isn't enough at design time, and what makes an acoustic number defensible: closed-form limits, conservation identities and measurement.
6 min read -
Why you can't understand a word in that room: reverb and intelligibility
Rooms where speech is hard to understand: the link between reverberation time, C50 clarity and intelligibility, and how to estimate and design the absorption.
3 min read -
MCU bring-up: the crystal that won't oscillate and the unreadable serial
Two embedded bring-up classics: the crystal that won't oscillate from wrong load capacitance and the unreadable UART from a baud-rate error — both diagnosed.
4 min read -
Endianness and IEEE 754: the bug that sends you back to the datasheet
Read a 32-bit float register and get absurd numbers: big vs little endian, IEEE 754 decomposition and two's complement. How to decode the bytes correctly.
3 min read -
Why your FFT spectrum lies: spectral leakage and windows
Spectral leakage in the FFT: why an off-bin sine corrupts the read amplitude and masks weak nearby tones. Hann, Blackman, flat-top windows and ENBW for noise.
4 min read -
Filter in hardware or in software? The decision you make before the ADC
When a filter must be analog (anti-aliasing, EMI rejection) and when a digital IIR is better: tunable, steep, reproducible. A decision made before the ADC.
3 min read -
A measurement without uncertainty is not a measurement
Uncertainty budget per the GUM guide: type A vs B, /√3 and /√6 divisors, quadrature combination and expanded uncertainty U=k·u_c for a defensible calibration.
3 min read -
How many MIPI CSI-2 lanes does your camera need?
Dimensioning the MIPI CSI-2 camera link: from resolution, fps and bits-per-pixel to Gbps and lane count. The traps of blanking, lane rate, RAW vs YUV.
4 min read -
ISO 9613-2:2024 §7.4: what changes in the diffraction calculation compared with 1996
The second edition rewrites Dz and Kmet and introduces the z_min threshold. The formulas side by side, the reason stated by the standard itself, and how much the numbers move for low barriers and long distances.
6 min read -
OSM data limits
Footprint coverage and estimated heights: how OpenStreetMap data quality affects the acoustic propagation and diffraction calculation, and when to trust it.
3 min read -
Six acoustics tools for first-approximation calculations, in the browser
Level composition, differential criterion, Maekawa explorer, LEX,8h, reverberation time and DPR 142/04 road-noise check: six free browser tools, sharing their physics engine with acmap and barrier-calculator.
4 min read -
Two acoustic tools online: acoustic map and noise-barrier calculator
ST-LINE Open Lab's two browser acoustic tools are live: acmap v0.5 for surveys and propagation and noise-barrier-calc v0.8 for insertion loss — open source.
3 min read -
NetProbe: what we built and why we built it this way
NetProbe, a passive on-premise network probe with local AI for Italian SMEs: from an internal NIS2/ISO 27001 audit tool to a product. Status and architecture.
6 min read -
STM32N6: porting the UVC H.264 hardware demo from EVAL to Nucleo
ST's new STM32N6 puts a Cortex-M55 with Helium, an ISP, a hardware H.264 encoder and an NPU on one chip. We ported the official UVC demo from EVAL to Nucleo.
4 min read -
An internal tool that ended up in the vendor's official documentation
We had written a Python GUI to characterise a difficult CMOS sensor. Months later, a technical email to Arducam changed the nature of the open-source tool.
4 min read -
Taking a USB Power Delivery stack outside its silicon
NXP's USB-PD middleware runs natively on NXP. We refactored it to run on ESP32-S3, STM32 and Arduino as well — with a clean HAL adapter and a single policy engine.
4 min read -
High-speed clinical imaging at 250 fps: the problem shifts from silicon to channel
Capturing 250 fps at VGA on an STM32N6 and streaming H.264 over Wi-Fi 6 for 30 minutes. The bottleneck isn't where the datasheet tells you — it's the channel.
4 min read -
Welcome to the ST-LINE technical blog
We're opening a space to share the technical decisions, field lessons, and tools we use to build electronics, firmware, software, acoustics and medical devices.
1 min read