D/A Conversion Using PWM and R-2R Ladders to Generate Sine and DTMF Waveforms
Rob Stein, John Day
Many embedded applications require the generation of analog signals. Although separate D/A converter IC?s exist on the market today, their extra price makes them prohibitive in cost sensitive embedded control designs. The following application note describes two DAC designs for generation of complex analog waveforms.: (PWM and R-2R Ladder). Both the Pulse Width Modulation (PWM) and resistor ladders require only a few external components to create a D/A converter with the PICmicro? microcontroller series. These techniques can be used to generate dual-tone multiplexed frequencies (DTMF) for telephone dialing, controlling the speed of a motor, generating sound and complex waveforms, and generating variable voltages in a power supply.