Brain Bots

40 minchallenge

MISSION 36 · INTERMEDIATE ARDUINO

Spill Spotter Model

Make spill spotter model. Explore conductivity and dry/damp calibration.

Public beta missionThese revised instructions are open for learning while actual-kit testing is pending. A grown-up must confirm every setup check before power is connected. If a rating, pin card or required check is missing, explore the idea on screen and leave the physical build unpowered.

5 · Inventor Arcade

Your new skill: Conductivity and dry/damp calibration

Revisit the skill you will reuse: room survey logger

Meet the parts

Match the names to your parts before you build. New parts appear when you first need them. You can point, say the name or show a grown-up.

Water sensor board New here

Conductive contact on exposed tracks changes its reading.

Spot it and try it

Look for: Metal tracks plus labelled supply/signal terminals.

Before using it: Only tracks touch damp tissue briefly; connectors stay dry.

Your turn: Measure dry and damp before choosing a threshold.

WHAT YOU'LL USE

Match these to your kit

Arduino UnoUSB A-to-B data cableHalf-size breadboardMale–male / male–female jumper wires (as needed for actual module terminals)Water sensor board, 1 LED, 1 × 2.2 kΩ

Gather from home

Computer with Arduino IDE and Serial MonitorShallow trayTissueClean waterHousehold spoon or dropperPaper towel

Reuse the parts between missions; these are not 45 simultaneous installations. Red/yellow/green means those three monochrome colours. RGB is a separate component with three channels.

BEFORE YOU BUILD

Unplug USB before changing connections. Use only the USB supply for this build; never connect 9V to 5V or a signal pin, and never connect to mains. An adult verifies variant, printed pin labels and resistor values before powering. Stop and unplug if a part becomes hot or damaged. Adult handles damp tissue. Keep Uno/computer and connectors dry and outside tray; wet only exposed tracks briefly. Do not run unattended.

YOUR REWARD

+30 XPMission completion

PREDICT BEFORE YOU BEGIN

Before the test: which input will change, and what signal or reading do you expect?

BEFORE YOU BUILD

Parent check: exact part variant, labelled pins and stated values. If a check cannot be confirmed, keep this physical build unpowered and explore the code and prediction instead.

YOUR CHALLENGE

Build spill spotter model and prove its rule.

NEW POWER-UP

Conductivity and dry/damp calibration

You have explored labelled sampling and comparison. Now try conductivity and dry/damp calibration.

Adult help: Adult helps with computer setup, first wiring and any water/cutting. Learner predicts, tests and explains.

See the idea before you build

How a breadboard connects inside

Each coloured strip is one connected group. Different numbered rows stay separate. This explains the board; use the mission’s exact connection reference for component positions. Check rail breaks on your supplied board.

system loop learning diagram — See the idea, then follow this mission’s exact pin-to-pin map below. · Tap to enlarge

Exact labelled connections for Spill Spotter Model — Pin-to-pin reference for this sketch. Match printed labels and actual component variant. · Tap to enlarge

Open the complete Arduino code

Copy the complete code into Arduino IDE or download the sketch. Follow the matching component card before connecting power.

// First Wonder Brain Bots 36 — Spill Spotter Model
// USB-powered model. Unplug before rewiring. Serial Monitor: 9600 baud.
unsigned long lastReport=0;
int wetThreshold=400;
bool wetIsHigh=true;
void report(int value){if(millis()-lastReport>=500){lastReport=millis();Serial.println(value);}}

void setup(){Serial.begin(9600);pinMode(8,OUTPUT);digitalWrite(8,LOW);Serial.println("Ready. Follow your mission test.");}
void loop(){
  unsigned long now=millis();
  
int value=analogRead(A1);bool wet=wetIsHigh?value>wetThreshold:value<wetThreshold;digitalWrite(8,wet);report(value);
}

Check the connection map

CONNECTION MAP

Build the electrical path before you test.

Keep power disconnected while changing connections.

JoinConnectWhy it matters

PowerSupplied USB data cable → Uno USB socket; computer at other endThe same cable uploads and supplies this model. Unplug before wiring.

Shared referenceUno GND → breadboard ground railAll module GND terminals use this same reference. Check whether your rail is split.

LED cue 1D8 → 2.2 kΩ → LED anode (+); cathode (−) → GNDUse separate breadboard strips. Short leg/flat rim usually marks cathode; verify.

Water boardVerified + → 5V; − → GND; S/analog signal → A1Keep supply and connectors outside the tray; only tracks touch damp tissue.

Kit variant and values confirmed by an adult

All pins match the map; USB was disconnected while wiring

Test includes expected, non-triggering and recovery cases

BUILD PATH

STEP 1 OF 6

Meet your mission

Try · Notice · ExplainRead the checkpoint, make a prediction, then test your idea.

You will explore conductivity and dry/damp calibration. Gather the kit and home materials below. Unplug USB. Match the part names and printed labels.

Watch this step

A video demonstration will appear here when it is ready. You can follow the written step now.

Read the video instructions

You will explore conductivity and dry/damp calibration. Gather the kit and home materials below. Unplug USB. Match the part names and printed labels.

Need a diagram for this step?

WHAT'S REALLY HAPPENING?

Why it works

Conductivity and dry/damp calibration. Water tracks respond to conductivity and contact, not universal depth or plant health. Check your rule against an example where it should respond and one where it should not. Conductivity and contact on its tracks.

This is a tabletop learning model. Real systems also need reliable power, robust sensors and careful handling of unknown measurements; this kit model is not a safety or security device.

FAIR-TEST CHALLENGE

Change one input or setting at a time; keep the wiring and protection unchanged. Repeat three trials.

WHEN IT DOESN'T WORK YET

Debug one clue at a time.

Upload or port missing

Likely cause: Wrong board, port or cable connection

Try this first: Check Arduino Uno selection and supplied data cable. Unplug external wiring before checking upload on built-in LED.

Signal does not match the test

Likely cause: Pin labels, input calibration or variant differs

Try this first: Unplug. Compare every connection with the map. Return to the earlier single-input mission; test one subsystem at a time.

Reading is unknown or unstable

Likely cause: Sensor settling, target, contact or calibration

Try this first: Follow the exact test setup; allow settling, use a flat target or check module pinout unpowered. Never replace unknown with a guessed safe reading.

CLEAN, RESET AND STORE

Disconnect USB, remove wires carefully and store components dry.

NEXT SKILL

Duration states and acknowledgement