Abstract: The method and the device thereof for dynamically calibrating a frequency is provided. The method includes steps of: (a) providing a first system frequency; (b) obtaining a first parameter of timer counting number; (c) providing a second system frequency; (d) obtaining a second parameter of timer counting number if there is a frequency drift between said first system frequency and said second system frequency; (e) obtaining a third parameter of timer interrupt interval by comparing said first parameter of timer counting number with said second parameter of timer counting number; and (f) calibrating a frequency output according to said third parameter of timer interrupt interval.

Abstract: The method and the device thereof for dynamically calibrating a frequency is provided. The method includes steps of: (a) providing a first system frequency; (b) obtaining a first parameter of timer counting number; (c) providing a second system frequency; (d) obtaining a second parameter of timer counting number if there is a frequency drift between said first system frequency and said second system frequency; (e) obtaining a third parameter of timer interrupt interval by comparing said first parameter of timer counting number with said second parameter of timer counting number; and (f) calibrating a frequency output according to said third parameter of timer interrupt interval.

Abstract: An improved opening structure of an unfolded umbrella includes a shaft with an upper mounting ring, a runner around the shaft, a frame having many ribs connected with the upper mounting ring and the runner, a button mounted on the shaft to engage with the runner for closing the umbrella. A rod is provided in the shaft at a lower position, an aperture is formed on the shaft with a wheel, and an elastic rope having one end connected with the rod and the other end extending upward to pass by the wheel, and to connect with the runner. When the umbrella is closed, the elastic rope is stretched that obtains a recovering force to open the umbrella quickly and automatically when the runner is unlocked.