Abstract: The invention is a frequency switching method of a CPU in electronic devices. The electronic device is comprised of a display screen and the CPU. The screen display changes according to the pixel clock. The method lowers the frequency of the pixel clock, switching the CPU frequency, and then restores the frequency of the pixel clock.

Abstract: A portable electronic device equipped with multi-function high speed bus and the relevant method is provided in the invention. The portable electronic device includes a main electronic apparatus for connecting to an expansion device through an expansion pack. The central processing unit (CPU) of the main electronic apparatus is connected to the host controller by a first system bus. The host controller is connected to the expansion pack by a multi-function high speed bus. The first system bus is electrically connected to the CPU and includes P signal lines; the multi-function high speed bus includes Q signal lines, where Q<P. The host controller bridges the signals from P signal lines of the first system bus and the signals from the Q signal lines of the multi-function high speed bus. The host controller receives the signals from the first system bus in M clock cycles and outputs the signals to the multi-function high speed bus in N clock cycles, where N>M.

Abstract: The invention is a frequency switching method of a CPU in electronic devices. The electronic device is comprised of a display screen and the CPU. The screen display changes according to the pixel clock. The method lowers the frequency of the pixel clock, switching the CPU frequency, and then restores the frequency of the pixel clock.