METHOD AND DEVICE FOR COMMUNICATING DATA BY PWM SIGNAL

PURPOSE:To prevent pulse width from being erroneously detected due to the fluctuation of a DC component on a reception-side by canceling the DC component as the signal average value of PWM data with an equivalent signal. CONSTITUTION:A count pulse is given to the clock terminal of an up/down counter 14 from a count pulse oscillator 22, and PWM data consisting of plural PWM signals is given to an up/down control terminal through a switch means 12. When the count value of the counter 14 is more than '1', a reset/set flip flop 24 outputs 'L', and outputs 'H' when the value is less than '0'. An equivalent pulse whose duty ratio is considerably deviated from the ratio of 50% is given to an Ex-OR circuit 18 from an equivalent pulse oscillator 26, and it is outputted as it is or by being inverted by the output of the flip flop 24 as the equivalent signal through a switch means 16. The switch means 12 is controlled by a sequencer 20 and a PWM data period and an equivalent signal period are periodically alternately transmitted.