The digital signals used in this project are three input pulse signals from the encoder, six output PWM
signals for the inverter and five normal input and output signals. The F28335 DSP employs Low-Voltage
TTL(LVTTL), which defines that VCC = 3.3V ; VOH > 2.4V, VOL 6 0.4V ; VIH > 2V, VIL 6 0.8V . The
digital signals can not be connected to the DSP directly until they have been conditioned since they are in
the range from 0V to 5V and not in the range from 0V to 3.3V as those produced by the DSP