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learn:fundamentals:circuits:basic-digital-io:start [2016/08/08 19:05] – created Marthalearn:fundamentals:circuits:basic-digital-io:start [2022/10/04 11:38] (current) – external edit 127.0.0.1
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 Circuits often require inputs that come directly from users (as opposed to inputs that come from other devices). User-input devices can take many forms, among them keyboards (as on a PC), buttons (as on a calculator or telephone), rotary dials, switches and levers, etc. Digilent® boards include several input devices, typically including push buttons and slide-switches. Since digital circuits operate with two voltage levels (LHV or Vdd, and LLV or GND), input devices like buttons and switches should be able to produce both of these voltages based on some user action. Circuits often require inputs that come directly from users (as opposed to inputs that come from other devices). User-input devices can take many forms, among them keyboards (as on a PC), buttons (as on a calculator or telephone), rotary dials, switches and levers, etc. Digilent® boards include several input devices, typically including push buttons and slide-switches. Since digital circuits operate with two voltage levels (LHV or Vdd, and LLV or GND), input devices like buttons and switches should be able to produce both of these voltages based on some user action.
- +{{ :learn:fundamentals:circuits:basic-digital-io:pushbutton.png?direct&200 |Figure 1. Push button switch}}
-{{ :learn:fundamentals:circuits:basic-digital-io:pushbutton.png?direct |Figure 1. Push button switch}}+
  
 The slide switches are also known as //single throw-double pole// (STDP) switches, because only one switch (or throw) exists, but two positions (or poles) are available (a pole is an electrical contact to which the switch can make contact). These switches can be set to output either Vdd (when the actuator is closest to the board's edge) or GND. The push button switches are also known as “momentary” contact buttons, because they only make contact while they are actively being pressed—they output a GND at rest, and a Vdd only when they are being pressed. The figure below shows typically push button and slide switch circuits used on Digilent boards. The slide switches are also known as //single throw-double pole// (STDP) switches, because only one switch (or throw) exists, but two positions (or poles) are available (a pole is an electrical contact to which the switch can make contact). These switches can be set to output either Vdd (when the actuator is closest to the board's edge) or GND. The push button switches are also known as “momentary” contact buttons, because they only make contact while they are actively being pressed—they output a GND at rest, and a Vdd only when they are being pressed. The figure below shows typically push button and slide switch circuits used on Digilent boards.