Wilteq WILTEQArduino Self-Study
Week 5 · Analogue, PWM & Task A

Session 22: Analogue inputs and the ADC

Teach & build120 minLesson 14: Analogue Inputs, ADC & Voltage Dividers

Learning outcomes

  • Explain how the Uno's 10-bit ADC turns 0-5 V into 0-1023
  • Wire a potentiometer as a voltage divider into A0
  • Convert counts to volts and percent
  • Compare a calculated voltage with a multimeter reading

Kit and components

  • Uno, 10 kΩ potentiometer, breadboard, jumpers
  • Multimeter

Pre-reading about 25 min

Students read these on their phones before class. They are listed on the student Before class page.

  1. Lesson 14: What the ADC does
  2. Lesson 14: Voltage divider and the potentiometer
  3. Lesson 14: Scaling counts to volts and percent
  4. Theory Reference: analogRead()

Session plan

  1. 0:0010 min
    Recap

    Quiz: fault finding

  2. 0:1020 min
    Demo

    Counts, volts and percent

    Turn the pot while Serial shows counts; convert to volts on the board and to percent with map().

  3. 0:3030 min
    Measure

    Calculated against measured

    Students set the pot to five positions and record the count, the calculated voltage and the multimeter voltage, then find the largest difference.

  4. 1:0045 min
  5. 1:4515 min
    Wrap-up

    Where does the error come from?

    Discuss the lesson's measurement uncertainty section using the class tables.

Checkpoint: ready to move on?

Students' calculated and measured voltages agree within about 0.05 V at every recorded position.

Extension for fast finishers

Read the optional LM4040 AREF appendix and explain how a precision reference changes the conversion.

Catch-up path

Fill in the table with the worked sketch unchanged, and revisit float division from S4.

Homework and practice

Code Along 10.3 and 10.5.

Facilitator notes

  • Leave the potentiometer wired: S23 uses it to control PWM.
← Session 21Session 23 →