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Measuring Voltage, Current and Continuity with the Digital Multimeter

Use the simulator's built-in Digital Multimeter to probe a working circuit — read the voltage across a resistor, the current through an LED, and check whether two points are connected, just like the real bench tool.

Note: the Digital Multimeter is a Premium-tier component in the simulator — you’ll need a Premium or VIP plan to use it there.

Try this directly in the free Raspberry Pi 4B simulator — no hardware or signup required. New to the GPIO header? Start with the interactive pinout guide.

What you’ll need

  • Raspberry Pi 4B
  • LED
  • Resistor (220Ω)
  • The Meter tool (top bar) — not a component you place

Step by step

  1. Build a simple circuit: drag a Raspberry Pi 4B, a Resistor (220Ω) and an LED onto the Canvas. Wire Pi pin 37 → the resistor, the resistor → the LED's anode (long leg), and the LED's cathode → a Pi GND pin (for example pin 39).
  2. Go to the Code tab and add a script that turns pin 37 on, then click Start:
import RPi.GPIO as GPIO
 
GPIO.setmode(GPIO.BOARD)
GPIO.setup(37, GPIO.OUT)
GPIO.output(37, GPIO.HIGH)

The Digital Multimeter is a tool, not a part: you don't drag it onto the canvas. It works on a circuit you've already built, and it never changes that circuit. It is available on Premium and VIP accounts.

  1. Click the Meter button in the top bar. A multimeter panel appears at the top right of the canvas with three modes: V (voltage), Ω (resistance / continuity) and A (current). Press Esc or the ✕ to close it.
  2. Measure voltage. Stay on V, click one end of the resistor (the red probe), then the other end (the black probe). Probes show as red and black rings on the pins.

The readout shows the voltage across the resistor: about 1.300 V. That's the 3.3V supply minus the roughly 2.0V a red LED drops. Click just one pin and the black probe defaults to ground, so you read that point's voltage to ground instead.

  1. Measure current. Switch to A and click the wire between the resistor and the LED. Real ammeters go in series, so the meter breaks that wire and reads the current through the loop.

You'll see about 5.91 mA — (3.3V − 2.0V) ÷ 220Ω. Click a different wire in the same loop and the current is the same, because it's a single loop.

  1. Check continuity. Stop the simulation, switch to Ω and click two pins — for example the resistor's two terminals.

Across the resistor you'll read 220 Ω with a CONNECTED indicator. Two points that aren't joined by any path show OPEN. Continuity works whether or not the simulation is running.

What “working correctly” looks like

  • Voltage across the resistor reads about 1.3 V while pin 37 is HIGH, and the LED's own voltage reads about 2.0 V.
  • Series current reads about 5.9 mA, and drops to "—" when pin 37 is driven LOW (nothing is driving the loop).
  • Continuity across the resistor reads 220 Ω; across two unconnected points it reads OPEN.
  • Nothing about your circuit changes while you measure — probes never move or edit parts.

If something’s wrong

  • Voltage or current reads 0 → click Start first; power and driven pins only exist while the simulation is running. Continuity is the one mode that also works while stopped.
  • The current reading shows "—" → there's no complete loop from a power source (or a pin driven HIGH) through the wire you clicked to ground, or the pin is driven LOW.
  • "Floating" instead of a voltage → that point isn't connected to any source or ground.
  • Clicking a pin draws a wire → the Meter tool isn't active; click Meter in the top bar first.
  • The Meter button asks you to upgrade → the multimeter is a Premium tool; sign in with a Premium or VIP account.
  • Readings are estimates for simple series circuits: a circuit with parallel branches may show "—" or an approximate value rather than an exact one.