https://embeddedcoffe.my.id/Recent content on Embedded CoffeHugoen-USTue, 25 Aug 2026 11:00:00 +0000https://embeddedcoffe.my.id/posts/designing-low-noise-power-supplies/Tue, 25 Aug 2026 11:00:00 +0000https://embeddedcoffe.my.id/posts/designing-low-noise-power-supplies/<p>High-resolution analog-to-digital converters (24-bit Delta-Sigma ADCs like the ADS1256 or AD7175) require millivolt-clean reference rails. A few microvolts of ripple on your $V_{REF}$ or $AV_{DD}$ can easily degrade effective number of bits (ENOB) from 20 bits down to 14 bits.</p> <h2 id="linear-regulators-vs-switcher-post-regulation">Linear Regulators vs Switcher Post-Regulation</h2> <p>While buck converters offer &gt;90% power efficiency, their high $di/dt$ switching harmonics can radiate across PCB planes. The best practice for mixed-signal systems is a hybrid <strong>SMPS + Low-Dropout (LDO)</strong> topology:</p>https://embeddedcoffe.my.id/posts/marine-nmea-2000-esp32-gateway/Thu, 20 Aug 2026 08:15:00 +0000https://embeddedcoffe.my.id/posts/marine-nmea-2000-esp32-gateway/<p>Marine electronics rely on <strong>NMEA 2000</strong> (N2K), a standardized protocol built on top of Bosch CAN 2.0B (Controller Area Network) operating at 250 kbps with J1939-based 29-bit identifiers.</p> <p>In this project, we design an isolated hardware gateway that bridges N2K PGN messages directly into an MQTT stream for vessel dashboards.</p> <h2 id="hardware-architecture--galvanic-isolation">Hardware Architecture &amp; Galvanic Isolation</h2> <p>Boats often have multiple battery banks with distinct ground references. Directly connecting an ESP32 to the CAN bus without isolation risks ground loops, alternator noise, and damaged silicon.</p>https://embeddedcoffe.my.id/posts/stm32-freertos-task-scheduling/Mon, 10 Aug 2026 14:30:00 +0000https://embeddedcoffe.my.id/posts/stm32-freertos-task-scheduling/<p>When transitioning from a simple super-loop (<code>while(1)</code>) architecture to a Real-Time Operating System (RTOS), understanding the scheduler&rsquo;s behavior is vital for predictable and crash-free execution.</p> <p>In this article, we dissect how FreeRTOS manages task context switching on ARM Cortex-M4 cores (STM32F4/G4 series) and how to avoid classic concurrency pitfalls.</p> <h2 id="the-cortex-m-pendsv-exception">The Cortex-M PendSV Exception</h2> <p>FreeRTOS relies on the <strong>PendSV</strong> (Pended Service Call) exception to perform context switches safely. Unlike hardware ISRs that must execute with minimal latency, PendSV is configured with the lowest interrupt priority.</p>https://embeddedcoffe.my.id/about/Sat, 01 Aug 2026 00:00:00 +0000https://embeddedcoffe.my.id/about/<p>Hello! I&rsquo;m <strong>Habib Rahman</strong>, an embedded systems and firmware engineer passionate about low-level software architectures, bare-metal C programming, real-time operating systems, and mixed-signal hardware design.</p> <p><strong>Embedded Coffe</strong> is my personal corner on the web where I document engineering notes, architecture deep dives, late-night hardware debugging sessions, and practical telemetry implementations.</p> <hr> <h2 id="what-i-work-on">What I Work On</h2> <ul> <li><strong>Bare-Metal &amp; Microcontroller Firmware:</strong> Writing deterministic drivers and bootloaders from scratch for ARM Cortex-M (STM32, NXP), RISC-V, and ESP32.</li> <li><strong>Real-Time Operating Systems (RTOS):</strong> Task scheduling, priority inversion mitigation, queue design, and memory protection using FreeRTOS and Zephyr.</li> <li><strong>Marine &amp; Industrial Telemetry:</strong> CAN Bus (CAN 2.0B / CAN-FD), NMEA 2000 (J1939 PGN handling), isolated transceivers, and robust IoT telemetry gateways.</li> <li><strong>Mixed-Signal Hardware Design:</strong> Multi-layer PCB design in KiCad, ultra-low noise power supply rails for precision ADCs, and signal integrity considerations.</li> </ul> <hr> <h2 id="the-lab-bench">The Lab Bench</h2> <p>My daily engineering workflow revolves around hardware debuggers and measurement instruments:</p>