| 摘要 |
PURPOSE: A circuit for detecting a horizontal synchronous signal of a display device is provided to improve the ability of a system by generating an interrupt in the case that there is no horizontal synchronous signal. CONSTITUTION: A circuit for detecting a horizontal synchronous signal of a display device includes the first counter(111), the second counter(112), a register(131), and the third counter(113). The first counter(111) counts a horizontal synchronous signal, and outputs numerous output signals. The second counter(112) receives the horizontal synchronous signal, and counts when all the output signals are 1 and 0. The register(131) stores the result of the second counter. The third counter(113) tests the result of the second counter(112) stored at the register for fixed time, and a count result of the third counter(113) is increased by 1 in the case that all values stored at the register are 0, and informs that there is no horizontal synchronous signal inputted to the first counter(111) by generating an overflow interrupt in the case that all values stored at the register(131) are 0 for fixed multiple of the fixed time. |
