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 → ESP32-C3 link through walls — plus what went wrong.
DS18B20 CRC errors on a short, correctly-terminated 1-Wire bus: eight probes on 2-3 m ribbon cable, a 4.7k pull-up, and a persistent failure rate the wiring does not explain.