Simple µC-Based ADCs -- Part I
by Dennis L. Feucht
Innovatia Laboratories
Microcontrollers (µCs) have become a common circuit element -- albeit a rather involved one -- in instruments, consumer and office electronics, automobiles, motion control, and nearly everything else. The µC manages the interface between the user and the electronics, setting parameters of analog and discrete digital circuitry. The increasing speed of µCs extends their use to dynamic (as in real-time) control, as control elements in feedback loops.
One useful dynamic application of µCs is as ADCs. ADCs over the years have gone from complete DVMs as instruments to embedded subsystems, to a few components. This two-part article presents some minimalist techniques for implementing µC-based ADCs.
Minimalist A/D Conversion
Multiple schemes have been devised over the years for A/D conversion.
Some are simple, not very fast, and not very precise, such as the single
ramp converter, as shown: charge a capacitor with a current source, thereby
generating a ramp.
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