Lecture 4

• what is the transfer function

  The functional relationship between physical input signal and electrical output signal
• what are the quality parameters of a sensor system

  • sensitivity
  • accuracy
  • precision
  • repeatability
  • range and span
  • stability (drift)
  • hysteresis
• what is sensitivity

  • the relationship between changes in input physical signal and output electrical signal
  • How well can the sensor detect changes in input value
  • Example: a thermometer would have "high sensitivity" if a small temperature change resulted in a large voltage change.
• what is accuracy

  measure of difference between the measured value and actual value. Generally defined as percentage of actual value.
• what is precision

  s the ability of an instrument to reproduce a certain set of readings within a given deviation.
• what is repeatability

  the ability to reproduce the output signal exactly when the same measured quantity is applied repeatedly under the same environmental conditions.
• what is range and span

  the limits between which inputs can vary. Span is maximum value minus the minimum value of the input.
• what is stability (drift)

  the ability to give same output when a constant input is measured over a period of time. Drift is expressed as percentage of full range output.
• what is hysteresis

  The dependency of system output on the system‘s previous state. When the system is given a certain input, the output depends on what the previous state of the system was.
• what is sensor output in the form of?

  • resistance change
  • voltage change
  • capacitance change
  • current change

  an appropriate circuit is required to measure these changes
• what do analog sensors, like the light sensor, often work as?

  a variable resistor because the resistance is directly influenced by the condition it measures
• what is a voltage divider circuit used for

  it can often be used to turn the changing resistance of the sensor into a proportional change of voltage
• what is a microcontroller

  a small, inexpensive computing device

  usually employed for sensing input from the real world and controlling devices based on that input
• what are the 3 tools for using Arduino?

  • the arduino microcontroller (actual hardware)
  • arduino working environment (the IDE built in Java)
  • language and compiler
• what are the reserved words called

  keywords
• what are the three sections in a sketch called

  • initialization
  • setup
  • loop
• what are the two parts of an Arduino program that run

  • setup()
  • loop()
• is the initialization part of the sketch required?

  not always, but some devices need to be initialized when the microcontroller starts up
• what is the setup section used for

  set pin modes, initialize serial communication, etc.
• what is the loop section used for

  code to be executed - reading inputs, triggering outputs, etc.
• what is the initialization section used for?

  contains all the variables and values that will be used throughout the program
• what do the constants HIGH and LOW mean?

  the voltage level for a digital pin, either 5V or 0V
• what do the constants INPUT and OUTPUT mean

  used for setting pins that can be used either for input or output
• which function/method is used for setting digital pins as input or output

  pinMode()
• what values does the analogRead() method read

  from 0 to 1023, representing the voltage being passed into the pin
• what values does the analogWrite() method read

  range from 0 to 255
• what does the millis() method return

  the number of milliseconds since the program started running