ST32 Off-Grid Inverter Firmware

I need production-ready firmware for an ST32-based household inverter that runs strictly in off-grid mode. The hardware stack already includes a lithium-ion pack with its own BMS, so the code you write should focus on orchestrating the inverter itself, not redesigning charge algorithms.

Core objectives
• Manage all off-grid operation modes, ensuring seamless transitions between battery, renewable input and load.
• Implement robust load management so priorities can be reassigned on the fly without brown-outs.
• Handle battery-backup logic—everything from deep-discharge cut-off through recovery—to protect both cells and downstream appliances.
• Integrate renewable energy sources (PV and wind are typical) while maintaining a clean, low-THD sine wave on the AC output.

Development notes
The microcontroller is an ST32 (ARM Cortex-M series). I am comfortable with you using STM32CubeIDE, HAL or LL drivers, and FreeRTOS if it keeps timing tight. The inverter’s gate signals are driven by a full-bridge topology; ADC channels are already routed for bus voltage, current sense and temperature feedback. An existing UART diagnostic console can be reused for debugging and firmware updates.

Deliverables
1. Fully commented C or C++ source, ready to build in STM32CubeIDE.
2. Binary image plus .elf for in-circuit flashing.
3. Configuration header where I can tweak load priorities and protection thresholds.
4. Brief PDF or Markdown that maps every peripheral and ISR used, along with test results showing a stable sine wave under varying loads.

Acceptance will be based on:
• Stable 230 V ± 3 % sine output (<3 % THD) from 10 % to 100 % load.
• Clean fail-over between solar input and battery without load drop.
• Verified protection triggers (over-current, over-temp, low-voltage) logged on UART.

If you have prior experience with STM32 motor-control libraries, SPWM or SVPWM, let me know; it will shorten our integration cycle.