This paper presents the development of "Control-Sync," a novel firmware for universal inverters in microgrids, designed to enhance grid stability and flexibility. As hybrid PV-battery systems become increasingly prevalent, there is a critical need for inverters capable of efficiently transitioning between grid-forming (GFM) and grid-following (GFL) modes. Our firmware introduces dual control paths that allow for seamless transitions without reliance on external control devices, reducing communication overhead and increasing operational reliability. Key features include direct phase-angle detection and frequency restoration capabilities, essential for managing asymmetrical power grids and dynamic load changes. The efficacy of Control-Sync is demonstrated through rigorous testing with grid emulators and multi-phase inverters, confirming its potential to improve microgrid reliability and efficiency. This study offers a scalable solution to enhance inverter adaptability in various grid conditions, fostering a more resilient energy infrastructure.