{ "schema": "tinyskiff.lessonPacket.v0", "lessonCode": "TSK-DAY14-TOUCH", "course": "TinySkiff ESP32-S3 Lab", "day": 14, "title": "Touch sensor: use your body as input", "status": "published", "learnerProfile": "adult beginner; curious and capable; no electronics assumed", "estimatedTimeMinutes": 25, "mission": "Wire an LED to GPIO 21, leave one bare jumper on GPIO 14 as a touch pad, and upload the sketch that flips the lamp every time your fingertip taps the wire — your body becomes part of the circuit.", "mainPath": "Arduino/C++", "sourceMetadata": { "officialPdf": "source/Freenove_Super_Starter_Kit_for_ESP32_S3-main/C/C_Tutorial.pdf", "chapter": "Chapter 9 Touch Sensor", "page": 105, "arduinoSketch": "source/Freenove_Super_Starter_Kit_for_ESP32_S3-main/C/Sketches/Sketch_09.2_TouchLamp/Sketch_09.2_TouchLamp.ino", "imageAsset": "docs/course/assets/day-14/circuit-page-105.png", "imageAlt": "Official Freenove circuit for the touch lamp: a bare jumper wire on GPIO 14 acting as a touch pad, and a LED on GPIO 21 through a 220 ohm resistor to ground, shown as both a schematic and a breadboard photo.", "licenseNote": "Based on Freenove official material released under CC BY-NC-SA 3.0; preserve attribution and non-affiliation language.\n" }, "parts": [ { "name": "ESP32-S3 board", "imageAsset": "docs/course/assets/shared/item-esp32-s3-board.jpg", "explanation": "A development board is a friendly package around a tiny computer chip. The ESP32-S3 runs your uploaded sketch, controls pins, reads sensors, and can also use USB, Wi-Fi, and Bluetooth. In this lesson, it sends the ping signal and measures the echo time." }, { "name": "GPIO extension board", "imageAsset": "docs/course/assets/shared/item-gpio-extension-board.png", "explanation": "GPIO means general-purpose input/output. These pins are connection points your code can use. The extension board makes them easier to see, reach, and wire without cramming everything onto the ESP32-S3 itself." }, { "name": "LED", "imageAsset": "docs/course/assets/shared/item-led.png", "explanation": "A LED is a one-way light. It only lights when its longer leg (the +) faces the pin and its shorter leg (the −) faces ground. Too much current burns it out, so a LED always sits behind a resistor." }, { "name": "220 Ω resistor", "imageAsset": "docs/course/assets/shared/item-resistor.png", "explanation": "A resistor limits how much current flows. Placed in series with the LED, the 220 Ω one keeps the current gentle enough to light the LED instead of burning it out. The bands of colour print its value, and it has no direction." }, { "name": "3 × jumper wires", "imageAsset": "docs/course/assets/shared/item-jumper-wire.png", "explanation": "Jumper wires make temporary connections without soldering. Female-to-male wires have a socket on one end and a pin on the other, useful when a sensor module and board use different connector styles." }, { "name": "Arduino IDE", "imageAsset": "docs/course/assets/shared/item-arduino-ide.png", "explanation": "Arduino IDE is the desktop app that opens the sketch, compiles it, uploads it to the ESP32-S3, and shows messages from the board in Serial Monitor." } ], "wiring": [ { "partPin": "Bare jumper end", "connectTo": "GPIO 14 (T14)", "reason": "The exposed metal tip is the touch pad your fingertip charges." }, { "partPin": "LED long leg (+)", "connectTo": "GPIO 21 via 220 Ω", "reason": "This pin holds the lamp on or off between touches." }, { "partPin": "LED short leg (−)", "connectTo": "GND", "reason": "Completes the LED's path back to zero volts." } ], "coachInstructions": [ "Reassure the learner there is no sensor module to find — the touch pad is a single bare-ended jumper on GPIO 14.", "Keep the two pins straight — T14 is GPIO 14 for the touch pad and the LED lives on GPIO 21; never let them swap in conversation or wiring.", "On this board a touch RAISES the touchRead value (idle in the tens of thousands, touch above 200000); correct any advice claiming readings near zero mean touch.", "If the LED never flips, have the learner upload Sketch_09.1_TouchRead and compare their own idle and touched numbers against PRESS_VAL and RELEASE_VAL before changing wiring.", "If the LED flickers, coach them to hold the jumper by its insulation and touch only the bare metal tip, deliberately.", "If the Serial Monitor shows nothing, check 115200 baud, the board, and the port before touching code." ], "steps": [ "Seat the ESP32-S3 on the GPIO extension board and keep USB unplugged while you wire.", "Place the LED so its long leg (+) is on the GPIO 21 side and its short leg (−) heads toward ground.", "Put the 220 Ω resistor in series between GPIO 21 and the LED's long leg.", "Push one end of a jumper into GPIO 14 and leave its other end free in the air — that bare metal tip is your touch pad.", "Compare every wire to the chart, then plug in USB.", "Open Sketch_09.1_TouchRead.ino first, upload it, and open Serial Monitor at 115200 — note the reading when the wire is alone and when you pinch its bare tip.", "Open Sketch_09.2_TouchLamp.ino and upload it.", "Tap the bare tip — the LED flips on. Tap again — it flips off." ], "codeFocus": { "arduino": [ { "line": "touchRead(T14)", "explanation": "Measures the charge on touch pin T14, which is GPIO 14 — your fingertip drives this number far higher." }, { "line": "touchRead(T14) > PRESS_VAL", "explanation": "On this board a reading above 200000 counts as a touch; a reading below 60000 counts as a release." }, { "line": "bool isProcessed", "explanation": "Remembers that the current touch has already been handled, so one tap flips the lamp exactly once." }, { "line": "digitalWrite(pin, !digitalRead(pin))", "explanation": "Reads the LED pin's current state and writes the opposite — the flip itself." } ] }, "theoryModel": { "plainLanguage": "Your fingertip adds capacitance the pin can measure; two thresholds and one remembered flag turn that raw number into a clean toggle.", "formula": "touch raises the reading — above 200000 is a press and below 60000 is a release", "notes": [ { "title": "On this board a touch pushes the number up", "body": "Idle, the pin reads in the tens of thousands; a firm touch climbs past 200000. Older ESP32 chips reported touch as a drop toward zero, and some reference text still describes that behaviour — on your S3, trust the thresholds in the sketch." }, { "title": "The same trick as the table lamp", "body": "The isProcessed flag plays the role debounce played on Day 5 — it holds the memory of one press so a long touch counts as a single tap." } ] }, "test": { "expectedOutputExample": [ "Tap the bare end of the wire — the LED flips on and stays on.", "Tap it again — the LED flips off.", "Serial Monitor at 115200 echoes each touch with \"Touch detected! \" and each let-go with \"Released! \"." ], "successCriteria": "This lamp latches — the LED holds its state between taps, with your fingertip doing the whole job of a button." }, "troubleshooting": [ { "symptom": "LED never flips", "firstChecks": [ "The thresholds may sit wrong for your setup — upload Sketch_09.1_TouchRead and read your own touched and untouched numbers." ] }, { "symptom": "LED flickers wildly", "firstChecks": [ "Hold the wire by its insulation and touch only the bare metal end, deliberately." ] }, { "symptom": "Nothing on the Serial Monitor", "firstChecks": [ "Set the monitor to 115200 baud, then re-check the board and port selections." ] }, { "symptom": "Upload fails", "firstChecks": [ "Swap in a data-capable USB cable." ] } ], "challenge": "Read your own touch numbers with Sketch_09.1_TouchRead, re-tune PRESS_VAL and RELEASE_VAL, then set the lamp to answer only a firm grip.", "logbookPrompts": [ "What did your untouched and touched readings turn out to be?", "Where did you finally set PRESS_VAL and RELEASE_VAL, and why?", "What everyday device would feel better with a touch control like this?" ] }