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Topic starter
2026-07-31 4:46 pm
From my ESP32.com post today:
Project: Heating System Monitor IV with ~50 µA average current; Outside BME280 Node!
Why use Heating System Monitor IV?
Answer questions your thermostat can't. A thermostat knows the setpoint. HSM IV knows what the system actually did: how many minutes the blower ran today, how long each cycle lasted, how long the house held temperature between cycles, and what the indoor and outdoor conditions were at the time. Over days and weeks, that data answers real questions:
• Is my system short-cycling?
• Which thermostat setpoint gives long, efficient cycles instead of frequent short ones?
• How does runtime track outdoor temperature? (Runtime per degree-day is your building's thermal signature — a sudden change flags a filter, refrigerant, or duct problem before the utility bill does.)
• Is the system degrading over time?
No electrical connection to your HVAC system. Blower detection is purely mechanical — an MPU-6050 IMU sensing vibration from outside the blower enclosure. Nothing is wired into the furnace or air handler. Nothing voids a warranty, nothing touches line voltage, and the whole monitor installs and removes without a trace — ideal for renters and apartments.
Owns its data. Every event is logged twice: locally to the ESP32's flash (LittleFS, retrievable over FTP) and to a perpetual Google Sheet that rolls month-to-month and year-to-year automatically. No cloud subscription, no vendor account, no app.
Survives real-world conditions. Runtime totals persist through power failures via NVS flash storage. A reset-reason log distinguishes normal power cycles from brownouts and watchdog resets. If the outdoor sensor node goes silent, its columns log "Offline" instead of silently repeating stale data. The outside node itself runs for years on battery power alone.
README.md includes Nordic Power Profiler Kit 2 Observations of the Outside ~50 µA average current BME280 Node.
73's (Best Regards)
William, AB9NQ
Topic starter
2026-08-06 2:37 am
~38.19 µA average current, ESP-NOW Outside BME280 Node
Update 8/5/2026 Switched to Channel Activity Detection (CAD) Interrupt on EoRa-S3-900TB, ESP-NOW BME280 outside node; from sx1262 "radio.startReceiveDutyCycleAuto()."
Nordic Power Profiler Kit 2 ~38.19 µA Average Current
Project Files updated 8/5/2026
Methodology note — CAD supersedes autoDutyCycle: The Hackster write-up’s published figures (51.30 µA average, ~83.5 months) were measured under the earlier autoDutyCycle WOR detection method. The project has since moved to CAD (Channel Activity Detection) as the pre-check ahead of the WOR receive window, which measurably reduces average current — 38.19 µA vs. 51.30 µA (a 25.6% reduction), improving theoretical battery life by 34.3% (~107.7 months vs. ~80.2 months) on the same 3000 mAh LiPo. The 51.30 µA / ~83.5-month figures should be considered superseded, not a number to reconcile against.
This project was the result of a collaborative engineering effort involving both hands-on experimentation and AI-assisted development. Each AI assistant contributed in different ways throughout the project.
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Claude – Lead AI for all aspects of the project. Helped maintain technical focus, reviewed the evolving documentation for clarity and consistency, and provided extensive assistance in coding, organizing, and refining the final Markdown document.
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Google Gemini – Provided valuable guidance during the migration to ESP32 Arduino Core 3.3.10, helping identify and avoid legacy code patterns from earlier ESP32 core releases. Gemini also contributed to development discussions involving SX1262 Channel Activity Detection (CAD), Wake-on-Radio (WOR), and ESP32-S3 Deep Sleep integration.
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ChatGPT – Assisted throughout firmware development, debugging, architecture discussions, RadioLib integration, power optimization, Nordic PPK2 measurement interpretation, battery-life analysis, and technical review of the final documentation.
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GitHub Copilot – Assisted with firmware implementation, code completion, and day-to-day development within the programming environment.
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Jan Gromeš – Special thanks for the outstanding RadioLib library!
The successful implementation of an ESP32-S3 Deep Sleeping Wake-on-Radio node using the SX1262 and RadioLib was made possible through this collaborative process. While the hardware design, firmware integration, measurements, testing, and final engineering decisions were performed by the author, the insights provided by each AI assistant significantly accelerated development and helped improve the quality and accuracy of the final project.
"Project not possible without everyone's help."
73's,
William, AB9NQ