Arduino components: what runs where

Relay

A relay module lets one Arduino pin switch a separate circuit, such as a lamp or a pump, with a mechanical switch.

Run the circuit you want to switch through the COM and NO terminals.

Through the Bridge, a Relay block drives IN LOW. Most hobby relay modules switch on at LOW, so they click on and stay on. A module that switches on at HIGH stays off. Pressing Stop drives IN HIGH again. A project the AI assistant built may store State off, which drives IN HIGH.

Test with nothing on COM and NO first: press Play, listen for the click and watch the module’s LED.

Mains safety: never wire 110 V or 230 V yourself. Stay within the relay’s rated current, use an enclosure, and have a qualified electrician wire anything that plugs into the wall.

See the Bridge and the Piezo buzzer.

Piezo buzzer

A piezo buzzer makes a tone when its pin is switched on and off quickly. Use a passive buzzer: an active buzzer only beeps at its own built-in pitch.

Add a Piezo block and set Frequency in Hz and Duration in ms. Through the Bridge it plays Frequency for Duration, and the sequence waits Duration plus 0.1 seconds before the next block. For a tune, chain Piezo blocks with different Frequency values: 262 Hz is middle C and 440 Hz is the A above it.

Your computer times the tone over the USB cable, so expect it to sound a little rough.

See the Bridge, or start a tune with a push button.

ESC

An ESC (electronic speed controller) powers a brushless motor from a battery and takes a servo-style signal from the Arduino.

Not recommended yet. Through the Bridge, any Speed of 40% or more sends the minimum throttle signal, so at the default 50% the motor won’t spin. Below 40% the throttle comes out about two and a half times the Speed you set, so 30% asks for about 77% throttle. ArduinoStudio has no ESC calibration step.

The battery connects to the ESC, never to the Arduino’s 5V pin. Remove propellers whenever you test.

For a motor you can drive today, see the DC motor guide.

Switch

A switch stays on or off after you flip it, unlike a push button that springs back.

You don’t need a resistor. In the simulator and over USB direct the internal pull-up is on, so a closed switch reads 0, which means on.

Add a Switch block, then a Check (If =, To On/Off, Choose on), then the blocks that should run while it’s on. Turn on Infinity Loop, because a Check reads the switch once per pass.

The push button guide walks through the same pattern step by step.

Potentiometer

A potentiometer is a knob. Turning it gives an analog reading from 0 to 1023.

Add a Potentiometer block, then a Check (If >, To %, Choose 50), then your actions, with Infinity Loop on. That means “continue only while the knob is past halfway”.

Use To % on every connection. Through the Bridge, To Custom compares against a second analog pin named by Choose, not against a number. The default To On/Off never passes for an analog reading.

The knob can’t set brightness, angle or speed yet.

The photoresistor guide uses the same analog pattern.

Proximity sensor

A Sharp GP2Y0A21YK infrared distance sensor measures roughly 10 to 80 cm and puts out a voltage the Arduino reads on an analog pin.

HC-SR04, SRF05 and the other sensors in the Controller list aren’t supported yet.

Through the Bridge: add Proximity, then a Check directly after it (If <, To Custom, Choose 20), then an action. Choose is in centimetres, and the Bridge waits until the reading is closer than that. After 30 seconds the Bridge stops holding up the sequence, but it keeps listening, so the blocks after the Check can still run later, even more than once with Infinity Loop on. Never put an action straight after Proximity: the Bridge always treats the next block as its Check.

In the simulator the same Check compares the raw slider value, not centimetres. See the Bridge and the DC motor guide.

IR motion sensor

A PIR motion sensor such as the HC-SR501 notices a warm body moving in front of it.

Give it 30 to 60 seconds to settle after power-up. Its two small dials set sensitivity and how long it holds.

Not working yet. The block has an Analog pin setting, but the Bridge listens on digital pin 0 instead, so a sensor wired to A0 never triggers it. No connection can run IR Motion today.

Switch something bigger with a relay, or start with a standard LED.

Joystick

A thumb joystick is two knobs in one: one analog reading for left and right, one for up and down.

Not working yet. Through the Bridge, the sequence carries on as soon as the joystick sends its first reading, without waiting for the stick to move. It also skips the block right after Joystick.

It can’t steer, use the stick’s position or read the push switch yet.

For a trigger that runs with nothing installed, use a push button.

Thermometer

An LM35 is a three-pin temperature sensor whose output voltage rises 10 mV for every °C.

Only the LM35 works. The block’s Controller stays at LM35, so the Bridge reads any sensor as one: a TMP36 comes out about 50 °C too high, and a DS18B20 needs firmware the Bridge doesn’t install.

Through the Bridge: add Thermometer, then a Check (If >, To Custom, Choose 30), then an action. Choose is in °C, so this waits until it’s warmer than 30 °C. After 30 seconds the Bridge stops holding up the sequence, but it keeps listening, so the blocks after the Check can still run later, even more than once with Infinity Loop on. Set To Custom so Choose takes a number; the default On/Off never triggers. There’s no live temperature display.

Switch a fan with a relay or a DC motor.

Hygrometer

A hygrometer measures relative humidity. Common hobby parts are the DHT11 and DHT22.

Humidity sensors don’t work in ArduinoStudio yet. The block stays set to DHT11, which isn’t a sensor the Bridge can drive, so the run stops there without a reading. None of the other sensors in its Controller list can be chosen yet either.

Leave it out of projects for now. If you want to react to the room, the thermometer works through the Bridge with an LM35.

Barometer

A barometer such as the BMP180 measures air pressure, which also gives a rough altitude.

Through the Bridge the block takes one reading. Nothing shows the pressure, and no block can act on pressure or altitude yet, so it only tells you the sensor answered.

The Bridge skips the block right after Barometer, so put a placeholder Check there.

Check where each block runs for sensors you can act on today.

Accelerometer

An accelerometer such as the ADXL345 measures tilt and movement as force along three axes, in g.

Through the Bridge: add Accelerometer, then a Check (If >, To Custom, Choose 1.5), then an action. It waits until the z axis reads above 1.5 g, then carries on after the Check. After 30 seconds the Bridge stops holding up the sequence, but it keeps listening, so the blocks after the Check can still run later, even more than once with Infinity Loop on.

The block’s own Threshold setting is ignored; the number in the Check’s Choose is the one that counts.

The IMU section covers the MPU6050.

Gyro

A gyro measures how fast something turns, in degrees per second around each of three axes.

The block does nothing useful yet. It stays set to ITG3200, which isn’t a sensor the Bridge can drive, so the run stops there without a reading. None of the other sensors in its Controller list can be chosen yet.

Have an MPU6050? The IMU block can talk to it.

IMU

An IMU combines an accelerometer and a gyro on one board. The block talks to an MPU6050.

Through the Bridge it takes one combined reading. Nothing shows the values and no block can act on tilt or motion yet, so it only confirms the sensor answers.

The Bridge skips the block right after IMU, so put a placeholder Check there.

To act on tilt today, use the Accelerometer block with an ADXL345.

Compass

A compass module such as the HMC5883L senses the Earth’s magnetic field to find a heading.

Mount it away from motors, speakers and magnets, which throw the reading off.

Through the Bridge the block takes one heading reading. Nothing shows it and no block can act on direction yet.

The Bridge skips the block right after Compass, so put a placeholder Check there.

Check where each block runs for sensors you can act on today.