1. An embedded system, comprising: a programmable device, storing program codes, consisting of a pin set for signal delivery, a micro controller, connected to the programmable device, controlling the programmable device via the pin set; an I/O interface, coupled to the micro controller, receiving a program code provided externally, in which a specific function is defined; wherein: the micro controller executes a command sequence to program the program code into the programmable device via the pin set; and the programmable device executes the programmed program code to provide the specific function.