Hands-on Raspberry Pi home monitoring: DS18B20, DHT11, ESP32-C3 over HC-12, CT-clamp energy metering, and migrating off RRDtool. Built and measured on real hardware.
DS18B20 CRC errors on a short, correctly-terminated 1-Wire bus: eight probes on 2-3 m of ribbon cable, a correctly sized 4.7k pull-up, and a persistent failure rate that the wiring does not explain β tuned toward the phrase people actually search.
Real numbers from a Raspberry Pi 4 running SQLite in WAL mode as a 24/7 home sensor logger: 1.25M rows, 5108 writes/hour, 4 MB WAL, zero corruption after 10 days of continuous writes.
DS18B20 parasite power vs 3-wire on long cable runs: why parasite power fails past ~3 metres on a 1-Wire bus, the physics behind the voltage collapse, and what 3-wire + 4.7k pull-up measured over 24 hours on the operator's 8-sensor bus.
The ESP32-C3 datasheet promises 5β7 Β΅A deep sleep. Your dev board draws thousands of times more. Here is what is actually leaking current in a XIAO ESP32C3 and how to measure it yourself.
The HC-12 433MHz serial bridge has no built-in retry or CRC at the UART passthrough level. Here is a practical application-level framing scheme with CRC-16, timeout-based retry, and backoff that actually worked on a live Pi 4 β ESP32-C3 link through walls β plus what went wrong.
Spot a fake DS18B20 on a Raspberry Pi: family-code check, sysfs CRC test, and ice/boil calibration against the datasheet. 3 of 7 probes in one batch were counterfeits, drifting 1.5β3.5 Β°C.
How rollup tables and a retention policy keep a Raspberry Pi sensor SQLite database from growing unbounded β and why SD-card wear is rarely the real problem.
CT clamp burden resistor calibration for ADS1115 on Raspberry Pi: pick the external burden, stabilise with a decoupling cap, and apply the DC-bias correction that separates a stable watt reading from drift β with the 51 Ξ© + 10 Β΅F combination I actually measured.
The HC-12 433MHz serial bridge has no built-in retry or CRC at the UART passthrough level. Here is a practical application-level framing scheme with CRC-16, timeout-based retry, and backoff that actually worked on a live Pi 4 β ESP32-C3 link through walls β plus what went wrong.
The ESP32-C3 datasheet promises 5β7 Β΅A deep sleep. Your dev board draws thousands of times more. Here is what is actually leaking current in a XIAO ESP32C3 and how to measure it yourself.
DS18B20 parasite power vs 3-wire on long cable runs: why parasite power fails past ~3 metres on a 1-Wire bus, the physics behind the voltage collapse, and what 3-wire + 4.7k pull-up measured over 24 hours on the operator's 8-sensor bus.
ADS1115 and CT clamps for whole-house energy monitoring on a Raspberry Pi: 15.6 days of real 60-second watt data, RMS burst code, and the calibration constant hiding a scale error.
How I ran my old RRDtool logger and its SQLite replacement in parallel for months β why you tee the reads instead of double-polling, and how to set a real cutover test before a monitoring-system migration.
DHT11 accuracy after 18 months of continuous logging on a Raspberry Pi: 26,318 rollup rows, 38% below the datasheet's 20 %RH floor, and where the part stops being usable.
Why asyncio does not make 1-Wire faster, and the collector pattern I actually run: per-plugin loops, to_thread for blocking buses, and one batched SQLite writer.
Nest SDM API rate limits are 5 QPM / 100 QPH per device. How I poll five thermostats from Python without tripping quotas, using devices.list and exponential backoff on 429.
Real numbers from a Raspberry Pi 4 running SQLite in WAL mode as a 24/7 home sensor logger: 1.25M rows, 5108 writes/hour, 4 MB WAL, zero corruption after 10 days of continuous writes.
How I migrated a two-year RRDtool logging setup to SQLite in WAL mode on a Raspberry Pi 4 β rescued 145,742 legacy rows, kept every historical data point, and used a parallel-run cutover to verify.
Why I moved my outdoor ESP32-C3 sensor nodes off WiFi and onto HC-12 433 MHz serial radio, the settings that mattered, and the failure modes nobody warns you about.
DS18B20 CRC errors on a short, correctly-terminated 1-Wire bus: eight probes on 2-3 m of ribbon cable, a correctly sized 4.7k pull-up, and a persistent failure rate that the wiring does not explain β tuned toward the phrase people actually search.
Raspberry-Pi (13) Ds18b20 (6) Sqlite (6) Sensors (5) 1-Wire (4) Calibration (3) Hc12 (3) Infrastructure (3) Python (3) 433mhz (2) Ads1115 (2) Asyncio (2) Crc (2) Ct-Clamp (2) Esp32-C3 (2) Migration (2) Rrdtool (2) Timeseries (2) Troubleshooting (2) Adc (1) Battery (1) Burden-Resistor (1) Deep-Sleep (1) Dht11 (1) Downsampling (1) Energy-Monitoring (1) Esp32 (1) Fake (1) Home-Automation (1) Home-Sensor (1) Humidity (1) I2c (1) Measurement (1) Nest (1) Oauth (1) Power (1) Retention (1) Retry (1) Rf (1) Sd-Card (1) Sdm-Api (1) Sensor-Network (1) Wal (1) Wiring (1)