Charter 20 · read · programme assignment

Plant Whisperer

Interactive Plant Label

Let visitors select a plant and see its nearby live conditions.

Difficulty
★★☆
Prefix
pw
Zone
visitor-centre
Type
whisperer
Device
pw-01
Build time
8 hours

Mission

Build this

An RFID, keypad, or remote-controlled OLED label linked to shared sensor topics.

One kit, one team repository.

Borrowed parts are labelled below and have a fallback. The assigned device ID is fixed; sensing and behaviour decisions remain yours.

Bill of materials

Parts

SourcePartFallback
● kitRC522, membrane keypad, or IR remote
● kitOLED
● kitSG90 servo

Disconnect USB before rewiring. Motors, the relay, and the servo need appropriate power and a shared ground. Never drive an actuator from the ESP32 3V3 pin.

Assembly

Build in evidence-producing steps

  1. Prove the connection first. Flash the unmodified first-message example with this charter’s zone, device type, and device ID.

    done when: pw-01 is alive on the developer view.

  2. Bench-test one input. Read the sensor or control in Serial Monitor before publishing or moving an actuator.

    done when: repeated physical conditions produce repeatable raw readings.

  3. Publish one registered measurement. Use the exact measurement and unit below.

    done when: the reading appears without a reject.

  4. Add the physical response. Keep spine.loop() running and avoid blocking delays.

    done when: repeated movement does not interrupt publishing or reset the board.

  5. Run the investigation. Collect the planned trials before tuning the final logic.

    done when: the build log contains observations, method, and a limitation.

Contract

Your topics

TopicUnitSuggested interval
garden/visitor-centre/whisperer/pw-01/selectionenumon selection

Read another team

garden/greenhouse-2/moisture-node/th-01/soil-moisture

Physical behaviour

Alive

Bow once after a valid selection and show a clear no-data state when needed.

Your call: Choose four plants and work with garden staff on concise facts.

Engineering evidence

Evaluate selection reliability and whether visitors understand the relationship between fact and live measurement.

  1. Run at least 30 labelled selection trials.
  2. Test the display with five new users.
  3. Report input failures and comprehension errors separately.

If you are fast: Publish aggregate selection counts without any visitor identifier.

Acceptance

Ready when all six are true

  • The registered device is alive and publishing its required topics.
  • The reject feed is clear after the final firmware starts.
  • The device reads at least one declared cross-team topic.
  • A physical output responds to real data without blocking MQTT.
  • The build log contains method, evidence, uncertainty, and a known limitation.
  • The enclosure exposes no unsafe wiring and the device ID can be scanned.

Backbone now

Live status

Updates from the same public event stream

Checking pw-01…