| 摘要 |
PURPOSE:To decrease the power consumption by allowing a master device to transmit a tri-state signal when the device transmits a master signal via a signal line, allowing a slave device to use one state in the said tri-state signal as the own clock signal and use other one-state as a slave signal to the master device so as to eliminate the need of a reference clock to the slave device side. CONSTITUTION:The master device 1 transmits a tri-state signal +1, 0, -1. That is, the signal level transmitted to the 1st signal line L1 till a time t1 is +1, and -1 between times t1-t2, 0 between times t2-t3, +1 between times t3-t4 and changes between the +1 -1 at a time t5 and succeeding times. The signal transmission from salve devices 2, 3 is discriminated from the output of a level discriminator 1b reaching zero because of short-circuit to both the signal lines L1 and L2 by the slave devices 2, 3,.... The power supply charging of the salve devices 2, 3,... at +1 output is made easy by comparing a resistance value of a current limit resistor 1f with that of a current limit resistor 1e and the circuit is improve for noise immunity and also the short-circuit current of the salve devices 2, 3,... at -1 output. |
