| 摘要 |
PURPOSE:To more simplify the circuit without degrading required functions by inputting a dummy signal to a reception circuit and reading timing synchronized with power supply frequency from the dummy signal. CONSTITUTION:This serial signal circuit is composed of the two circuits of a serial signal reception circuit 1 and a serial signal transmission circuit 2, and the serial signal reception circuit 1 uses an interruption port INT of a microcomputer 3. First of all, data at a Hi level corresponding to a power supply voltage waveform are transmitted through an input/output terminal 8 for serial signals, and these data are received. The microcomputer 3 can calculate the exact power supply frequency by reading time from the start of these data to the next start or from the end of those data to the next end several times. Then, timing for transmitting/receiving serial signals is calculated from this power supply frequency. Therefore, since a power source synchronizing signal reception circuit is unnecessitated, the number of parts is decreased. |
