Wio Terminal: Log Light & Sound to SD Card

Build a smart logger with Arduino and unleash environmental awareness—one analog read at a time.

Whether you're monitoring plant health, logging neighborhood noise, or running classroom experiments, the Wio Terminal makes it easy to record ambient conditions with its built-in sensors and microSD slot. Let’s dive into a complete walkthrough: hardware, code, real-world use cases—and ideas to expand it further.

🔧 What You’re Working With

🧠 Wio Terminal

An all-in-one embedded board from Seeed Studio packed with features:

• Display: 2.4” LCD for live feedback
• Sensors: Built-in light sensor (A0) and microphone (A2)
• Connectivity: Wi-Fi, BLE, USB-C, microSD slot
• Processor: ATSAMD51 ARM Cortex-M4F @ 120 MHz
• Easily programmable via Arduino IDE or CircuitPython

💡 Light Sensor

A photodiode connected to A0, sensing ambient light levels.

• Range: Analog 0–1023 (via analogRead)
• Perfect for tracking sunlight cycles, lighting conditions, or plant environments.

🔊 Microphone

An analog MEMS mic connected to A2 measuring sound amplitude—not full audio, just “how loud”.

• Use it for detecting noise patterns, claps, spikes, and loud events.
• Analog output—no speech recognition, but great for threshold alerts.

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🛠️ Step-by-Step Build: Logging Light & Sound

🪛 Hardware Checklist

📦 Arduino Setup

Install Seeed Boards Add to Arduino Preferences: https://files.seeedstudio.com/arduino/package_seeeduino_boards_index.json

Install Libraries via Library Manager

• Seeed_FS
• SD

Select Board & Port

• Board: Wio Terminal

• Port: Your USB device

Step 1: Display Light & Sound Sensor Data via Serial

Use this simple Arduino sketch to read the Light and Sound sensor data then show it via Serial Terminal.

#define LIGHT_PIN A0
#define MIC_PIN A2

void setup() {
  Serial.begin(115200); // Start Serial Monitor
  pinMode(LIGHT_PIN, INPUT);
  pinMode(MIC_PIN, INPUT);
}

void loop() {
  int lightVal = analogRead(LIGHT_PIN);
  int micVal = analogRead(MIC_PIN);

  Serial.print("Ambient Light: ");
  Serial.print(lightVal);
  Serial.print(" | Sound Level: ");
  Serial.println(micVal);

  delay(1000); // Update every second
}

Step 2: Display Light & Sound Sensor Data via GUI

Here’s a detailed and clean Arduino sketch to create a graphical interface using the Wio Terminal’s LCD:

#include <TFT_eSPI.h>

#define LIGHT_PIN A0
#define MIC_PIN A2

TFT_eSPI tft;

void setup() {
  Serial.begin(115200);
  pinMode(LIGHT_PIN, INPUT);
  pinMode(MIC_PIN, INPUT);

  tft.begin();
  tft.setRotation(3);
  tft.fillScreen(TFT_BLACK);

  // Title
  tft.setTextSize(2);
  tft.setTextColor(TFT_WHITE);
  tft.setCursor(50, 20);
  tft.println("Sensor Dashboard");

  // Static box outlines
  tft.drawRect(30, 70, 260, 40, TFT_YELLOW); // Light box
  tft.drawRect(30, 130, 260, 40, TFT_CYAN);  // Sound box
}

void loop() {
  int lightVal = analogRead(LIGHT_PIN);
  int micVal   = analogRead(MIC_PIN);

  // Box background refresh
  tft.fillRect(31, 71, 258, 38, TFT_DARKGREY); // Light box fill
  tft.fillRect(31, 131, 258, 38, TFT_DARKGREY); // Sound box fill

  // Display Light Value
  tft.setTextColor(TFT_YELLOW, TFT_DARKGREY);
  tft.setTextSize(2);
  tft.setCursor(40, 80);
  tft.printf("Light Level: %4d", lightVal);

  // Display Sound Value
  tft.setTextColor(TFT_CYAN, TFT_DARKGREY);
  tft.setCursor(40, 140);
  tft.printf("Sound Level: %4d", micVal);

  delay(500);
}

Step 3: Display Light & Sound Sensor Data via GUI

Here’s a detailed and clean Arduino sketch to create a graphical interface using the Wio Terminal’s LCD:

#include <SPI.h>
#include "Seeed_FS.h"
#include "SD/Seeed_SD.h"

File testFile;

void setup() {
  Serial.begin(115200);
  while (!Serial);  // Wait for Serial Monitor
  
  Serial.println("=== Wio Terminal SD Card Check ===");

  // Initialize SD card
  if (!SD.begin(SDCARD_SS_PIN, SDCARD_SPI)) {
    Serial.println("ERROR: SD card initialization failed.");
    return;
  }

  Serial.println("SD card initialized successfully.");

  // Detect card type
  uint8_t cardType = SD.cardType();
  Serial.print("Card Type: ");
  switch (cardType) {
    case CARD_MMC: Serial.println("MMC"); break;
    case CARD_SD: Serial.println("SDSC"); break;
    case CARD_SDHC: Serial.println("SDHC"); break;
    default: Serial.println("Unknown"); break;
  }

  // Show card size (safe casting)
  uint64_t cardSize = SD.cardSize(); // bytes
  Serial.print("Card Size: ");
  Serial.print((unsigned long)(cardSize / (1024 * 1024))); // in MB
  Serial.println(" MB");

  // Write test
  testFile = SD.open("/test.txt", FILE_WRITE);
  if (testFile) {
    testFile.println("Wio SD Write Test OK");
    testFile.close();
    Serial.println("Write test: SUCCESS");
  } else {
    Serial.println("Write test: FAILED");
  }

  // Read test
  testFile = SD.open("/test.txt");
  if (testFile) {
    Serial.println("Read test: SUCCESS");
    Serial.println("Contents of test.txt:");
    while (testFile.available()) {
      Serial.write(testFile.read());
    }
    testFile.close();
  } else {
    Serial.println("Read test: FAILED");
  }
}

void loop() {
  // No loop needed for this test
}

Step 4: Display Light & Sound Sensor Data via GUI record in SD

Here's a full Arduino sketch that reads the light and sound sensor values from the Wio Terminal and records them to an SD card file named env_log.txt every second. It’s modular, reliable, and ready for field deployment.

#include <SPI.h>
#include "Seeed_FS.h"
#include "SD/Seeed_SD.h"
#include <TFT_eSPI.h>

#define LIGHT_PIN A0
#define MIC_PIN A2

TFT_eSPI tft;
File dataFile;

void setup() {
  Serial.begin(115200);
  pinMode(LIGHT_PIN, INPUT);
  pinMode(MIC_PIN, INPUT);

  // Initialize LCD
  tft.begin();
  tft.setRotation(3);
  tft.fillScreen(TFT_BLACK);
  tft.setTextSize(2.5);
  tft.setTextColor(TFT_WHITE);
  tft.setCursor(50, 20);
  tft.println("Sensor Dashboard");

  // Draw box outlines
  tft.drawRect(30, 70, 260, 40, TFT_YELLOW); // Light box
  tft.drawRect(30, 130, 260, 40, TFT_CYAN);  // Sound box

  // Initialize SD
  if (!SD.begin(SDCARD_SS_PIN, SDCARD_SPI)) {
    Serial.println("ERROR: SD Card init failed.");
    tft.setCursor(50, 200);
    tft.setTextColor(TFT_RED);
    tft.println("SD Card Error");
  } else {
    Serial.println("SD Card ready.");
    tft.setCursor(50, 200);
    tft.setTextColor(TFT_GREEN);
    tft.println("SD Card Ready");
  }
}

void loop() {
  int lightVal = analogRead(LIGHT_PIN);
  int micVal   = analogRead(MIC_PIN);

  // Format log entry
  String logEntry = "Light: " + String(lightVal) + ", Sound: " + String(micVal);

  // Log to SD
  dataFile = SD.open("/env_log.txt", FILE_WRITE);
  if (dataFile) {
    dataFile.println(logEntry);
    dataFile.close();
    Serial.println("Logged: " + logEntry);
  }

  // Refresh GUI boxes
  tft.fillRect(31, 71, 258, 38, TFT_DARKGREY);
  tft.fillRect(31, 131, 258, 38, TFT_DARKGREY);

  // Display light value
  tft.setTextColor(TFT_YELLOW, TFT_DARKGREY);
  tft.setTextSize(2);
  tft.setCursor(40, 80);
  tft.printf("Light Level: %4d", lightVal);

  // Display sound value
  tft.setTextColor(TFT_CYAN, TFT_DARKGREY);
  tft.setCursor(40, 140);
  tft.printf("Sound Level: %4d", micVal);

  delay(1000);
}

Now let's review the data in the excel file.

🌍 Real-World Applications

🌱 Environmental Monitoring

• Track light levels near windows or plants over time
• Log sound levels around traffic-heavy or industrial areas

🏠 Smart Home Logging

• Detect sudden light changes (open doors/windows)
• Trigger actions when loud sounds are detected (e.g. clap = turn light on)

🧪 Education & STEM

• Use as a classroom demo for analog sensors
• Teach how to record and visualize data trends with CSV/Excel

📈 Bonus: Visualizing the Data

After logging:

• Remove the SD card, open env_log.txt
• Save as .csv
• Open in Excel or Google Sheets
• Plot light vs sound values over time

You could even build time-stamp logic using an RTC or millis() and add thresholds to trigger alerts.

🚀 Expand It Further

• Add visual feedback on the Wio Terminal screen
• Trigger events via Telegram alerts using Wi-Fi
• Sync data to Qubitro cloud for real-time dashboards
• Use Blues Wireless Notecard to offload logs over cellular IoT

🔗 Wrapping It Up

With just one device and a few lines of code, you've built a powerful light + sound data logger with real environmental applications. Whether you're studying noise patterns or watching daylight cycles, this setup makes exploration super simple—and it's fully expandable for IoT and edge AI magic.