| 摘要 |
PURPOSE:To prevent an error, by detecting a signal from one mechanical contact with two kinds of latch clock which have a greater phase difference than the chattering time of the mechanical contact, and reading it when both signals coincide with each other. CONSTITUTION:Switches SW1-SWn divide a contact signal 4 into two and input them to input ports 1 and 2. The input port reading of the input ports 1 and 2 is controlled by control signals 5 and 6, respectively and they are latched by the latch clocks 7 and 8 to send outputs 9 and 10 through a data bus 3 to a CPU which is not shown in a figure. Then, both outputs 9 and 10 are compared with each other and read as significant signals when coinciding with each other. The phase difference between the latch clocks is set greater than the maximum value of estimated chattering duration. Consequently, an error in reading the contact signal is prevented. |
