Portable electronic device comprising common serial bus connector

摘要

A portable electronic device according to the invention comprises a USB connector 4 , a USB controller 6 for executing predetermined data communication processing attendant on data communication with a personal computer 2 connected to the USB connector 4 , and a main CPU 7 for executing device operation processing for the usual operation of the device, and is adapted to receive a power supply from the personal computer 2 or an external power source 3 as connected to the USB connector 4 . Discriminating between the sources of supply of power, the main CPU 7 causes the USB controller 6 to execute the predetermined data communication processing while power is supplied from the personal computer 2 , or executes the usual device operation processing while power is supplied from the external power source 3 . This assures more rapid and simplified processing even when the USB connector is used also as a connector for the external power source.