OpenFOTA, ABUP's Over-the-Air (OTA) delta solution for Renesas RA 32-bit microcontrollers (MCUs), brings together experience from serving many IoT applications. It aims to upgrade the MCU memory with the help of the delta upgrade capability of modules and Flash resources, so that the main control program can achieve OTA function more easily and conveniently. OpenFOTA provides an integrated solution to the OTA upgrade of the whole system. It can upgrade not only modules but also main controls.