Single-board microcontroller: Difference between revisions

Revision as of 20:50, 15 March 2019

Revision as of 08:37, 6 May 2019

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Microcontroller systems provide multiple forms of input and output signals to allow application software to control an external "real-world" system. Discrete digital I/O provides a single bit of data (on or off). Analog signals, representing a continuous variable range, such as temperature or pressure, can also be inputs and outputs for microcontrollers.

Discrete digital inputs and outputs might be buffered from the microprocessor data bus only by an addressable latch, or might be operated by a specialized input/output IC, such as an [[Intel 8255]] or Motorola 6821 [[Peripheral Interface Adapter|parallel input/output adapter]]. Later single-chip micrcontrollersmicrocontrollers have input and output pins available. These input/output circuits usually do not provide enough current to directly operate devices like lamps or motors, so solid-state relays are operated by the microcontroller digital outputs, and inputs are isolated by [[signal conditioning]] level-shifting and protection circuits.

One or more analog inputs, with an analog multiplexer and common analog to digital converter, are found on some microcontroller boards. Analog outputs may use a digital-to-analog converter or, on some microcontrollers, may be controlled by [[pulse-width modulation]]. For discrete inputs, external circuits may be required to scale inputs, or to provide functions like [[Wheatstone bridge|bridge]] excitation or [[cold junction compensation]].