This paper presents an overview of visual programming environment named Splish which enables an icon-based visual programming to develop a program which runs on a microcontroller board family called Arduino which is a popular platform for physical computing. A user program can be developed visually on a PC side, and the compiled code will be transferred to the microcontroller board so that runtime environment of Splish can execute the complied code by interpreting the machine instructions of a simple virtual stack machine. This functional distribution allows the interactive debugging when the microcontroller board is connected to a PC. Because physical computing attracts wide variety of people including non-specialists and students, the visual programming and the interactive debugging capabilities of Splish will accelerate their physical computing experiences. Splish is developed with JavaFX to achieve platform independence.