Solar Thermal Controller Firmware Development -- 2

Freelance Embedded Firmware Developer (ESP32-S3)

We are looking for a freelance embedded firmware developer for a production-grade solar thermal controller.

Hardware
• ESP32-S3
• TUYA Wi-Fi module
• MODBUS RTU
• 2× PT1000 + ADS1115
• 230VAC 10A relay + external 12VDC trigger
• 2.8” UART capacitive HMI

Software Scope
• ΔT-based solar thermal control logic
• Multi-level safety & emergency protection
• Sensor fault detection & fail-safe logic
• Manual control mode via HMI
• TUYA remote control + OTA
• MODBUS integration
• TUYA / MODBUS mutual exclusion
• FreeRTOS-based architecture

Mandatory Skills
• Embedded C/C++
• ESP32-S3 with FreeRTOS
• Watchdog & power-loss handling
• Flash/NVS management
• State-machine design
• OTA rollback strategy
• Git

Engagement Model
• Milestone-based
• Source code + build setup + brief documentation
• Hourly work is not accepted

Application Requirement

Answer clearly:
1. How do you handle power loss during OTA?
2. How does the system react to sensor failure?
3. How would you implement watchdog reset in FreeRTOS?