Patent ID: 8179748
Filing Date: 2012-05-15
Classification: G11B

Abstract:
1. A limit switch controlling circuit used in an optical drive, comprising: a controlling chip, including a servo controlling unit, an appended-function unit, a switch, and a controlling pin, wherein the switch is for selectively connecting the controlling pin to the servo controlling unit or the appended-function unit; a resistance, connected between the controlling pin and a first voltage source; a first blocking device, having a first end connected to the controlling pin; a limit switch, connected to a second end of the first blocking device and a second voltage source, for selectively connecting the second voltage source to the first blocking device; a second blocking device, having a first end connected to the controlling pin; and an I/O port, connected to a second end of the second blocking device; wherein when the switch is controlled to connected the servo controlling unit and the controlling pin, the servo controlling unit determines whether the limit switch is connected to the second voltage or not, and when the switch is controlled to connected the appended-function unit and the controlling pin, the appended-function unit transmits/receives a signal to/from the I/O port respectively.