{ "schema": "tinyskiff.lessonPacket.v0", "lessonCode": "TSK-DAY18-THERMOMETER", "course": "TinySkiff ESP32-S3 Lab", "day": 18, "title": "Thermometer: sense temperature", "status": "published", "learnerProfile": "adult beginner; curious and capable; no electronics assumed", "estimatedTimeMinutes": 25, "mission": "Build a working thermometer from a thermistor and a 10 kΩ resistor, upload the Arduino sketch, and watch live temperature readings print in Serial Monitor — then pinch the bead and see the number climb.", "mainPath": "Arduino/C++", "optionalSidePath": "MicroPython", "sourceMetadata": { "officialPdf": "source/Freenove_Super_Starter_Kit_for_ESP32_S3-main/C/C_Tutorial.pdf", "chapter": "Chapter 12 Thermistor", "page": 123, "arduinoSketch": "source/Freenove_Super_Starter_Kit_for_ESP32_S3-main/C/Sketches/Sketch_12.1_Thermometer/Sketch_12.1_Thermometer.ino", "micropythonFile": "source/Freenove_Super_Starter_Kit_for_ESP32_S3-main/Python/Python_Codes/11.1_Thermometer/Thermometer.py", "imageAsset": "docs/course/assets/day-18/circuit-page-123.png", "imageAlt": "Official Freenove circuit for the thermometer: a 10 kilo-ohm resistor from 3.3V down to GPIO 1, and a thermistor from that same point 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": "Thermistor", "imageAsset": "docs/course/assets/shared/item-thermistor.png", "explanation": "A thermistor changes resistance with temperature. In a voltage divider its changing resistance becomes a changing ADC voltage, and a short formula (the B-equation, with B=3950 for this part) converts that resistance back into degrees. That's the whole thermometer." }, { "name": "10 kΩ 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": "10 kΩ resistor leg", "connectTo": "3.3V", "reason": "Feeds the divider from a steady 3.3 volts." }, { "partPin": "Divider midpoint", "connectTo": "GPIO 1", "reason": "The ADC pin reads the voltage where resistor meets thermistor." }, { "partPin": "Thermistor far leg", "connectTo": "GND", "reason": "Completes the divider's path back to zero volts." } ], "coachInstructions": [ "Guide one physical connection at a time and wait for learner confirmation before proceeding.", "The divider's layout is the day's main trap — 10 kΩ to 3.3V, thermistor to GND, and the row where they meet to GPIO 1.", "A reading near -273 or nan means the divider is open or shorted; check the GPIO 1 midpoint wire and the 10 kΩ resistor before changing code.", "If values freeze or ignore a pinch, have the learner reseat the thermistor's legs in their breadboard rows.", "Coach the pinch itself — fingers on the bead so body heat transfers; a climb of a few degrees is success.", "Keep the Arduino path primary; MicroPython is optional only if already set up." ], "steps": [ "Seat the ESP32-S3 on the GPIO extension board and keep USB unplugged while you wire.", "Push the thermistor into the breadboard with its two legs in separate rows.", "Place the 10 kΩ resistor so one leg shares a row with one thermistor leg — that shared row is the divider's midpoint.", "Run a jumper from 3.3V to the resistor's free leg.", "Run a jumper from the midpoint row to GPIO 1.", "Run a jumper from the thermistor's free leg to GND.", "Compare every wire to the chart, then plug in USB.", "Open Sketch_12.1_Thermometer.ino in Arduino IDE and upload it.", "Open Serial Monitor and set the baud rate to 115200.", "Pinch the thermistor's bead between two fingers and watch the temperature climb." ], "codeFocus": { "arduino": [ { "line": "analogRead(PIN_ANALOG_IN)", "explanation": "Reads the divider midpoint on GPIO 1 as a number from 0 to 4095." }, { "line": "double Rt = 10 * voltage / (3.3 - voltage)", "explanation": "Works the divider maths backwards to recover the thermistor's resistance in kilo-ohms." }, { "line": "log(Rt / 10) / 3950.0", "explanation": "The B-equation — B is 3950 for this bead — maps that resistance onto temperature in Kelvin; subtracting 273.15 lands it in Celsius." } ], "micropython": [ { "line": "adc.atten(ADC.ATTN_11DB)", "explanation": "Opens the pin to the full 0–3.3 V range so the divider's whole swing is readable." }, { "line": "Rt=10*voltage/(3.3-voltage)", "explanation": "The same divider arithmetic as the Arduino sketch — volts back into kilo-ohms." } ] }, "theoryModel": { "plainLanguage": "The thermistor's resistance moves with temperature; the divider turns resistance into voltage; the B-equation turns it back into degrees.", "formula": "ADC count → volts → ohms → degrees", "notes": [ { "title": "Why resistance moves", "body": "A thermistor is made of a material whose electrons flow more freely as it warms, so its resistance drops as temperature rises. At 25 °C this bead sits near 10 kΩ." }, { "title": "What the 10 kΩ partner does", "body": "The ADC measures voltage. Stacking the fixed resistor above the thermistor makes a divider whose midpoint voltage tracks the changing resistance — the translation the pin can actually read." } ] }, "test": { "expectedOutputExample": [ "ADC value : 2185,\tVoltage : 1.76V, \tTemperature : 22.00C", "ADC value : 2100,\tVoltage : 1.69V, \tTemperature : 23.85C", "ADC value : 2048,\tVoltage : 1.65V, \tTemperature : 24.99C" ], "successCriteria": "A steady room line first — somewhere around 20 to 26 °C. Pinch the bead and the temperature climbs a few degrees; let go and it eases back down." }, "troubleshooting": [ { "symptom": "Temperature wildly wrong — near -273 or nan", "firstChecks": [ "Check the midpoint wire on GPIO 1 and that the 10 kΩ resistor is in the divider." ] }, { "symptom": "Values frozen while you pinch", "firstChecks": [ "Reseat the thermistor's legs — one has likely lifted out of its row." ] }, { "symptom": "Garbled text", "firstChecks": [ "Set Serial Monitor to 115200 baud to match the sketch." ] }, { "symptom": "Upload fails", "firstChecks": [ "Swap in a data-capable USB cable." ] } ], "challenge": "Log your room's reading morning and evening, add a Fahrenheit line to the printout, then hold the bead and time how long it takes to read body-warm.", "logbookPrompts": [ "What did your room read this morning and this evening?", "How long did the bead take to reach body-warm while you held it?", "Where on a boat — or in your home — would a temperature sensor earn its keep?" ] }