Voltage-to-pulse-width converter spares microprocessor's resources

摘要

Although not an ADC in the classic "stream-of-ones-and zeros" sense, this voltage-to-pulse-width converter produces a logic-level output pulse whose variable width represents an analog of the input voltage. Based on Atmel's (www. atmel.com) AT89LP4052 microprocessor, IC{sub}1, this circuit makes efficient use of the target microprocessor's limited analog-port pinout and code space by using a modified version of the classic timed-discharge-RC (resistor-capacitor) ADC design.