Published January 16, 2020 © GPL3+

Environmental sensors cooperate with Seeeduino XIAO

This is a little demo with Seeeduino XIAO - Arduino microcontroller. The demo uses 4 modules. 2 sensors, 1 switch, and 1 OLED display.

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Environmental sensors cooperate with Seeeduino XIAO

Things used in this project

Hardware components

Seeeduino XIAO - Arduino Microcontroller - SAMD21 Cortex M0+

Seeed Studio Grove - Touch Sensor SKU 101020037

Grove - Digital Light Sensor - TSL2561

Grove - Temperature & Humidity Sensor (DHT11)

Grove - OLED Display 0.96" (SSD1315)

Grove - 4 pin Male Jumper to Grove 4 pin Conversion Cable (5 PCs per Pack)

Seeed - 400 Point Solderless Breadboard for Raspberry Pi and Arduino Project

Software apps and online services

Arduino IDE

Story

This is a demo based on Seeeduino XIAO and basic Grove sensors like DHT11 temperature & humidity sensor and light sensor to display the value on the SSD1315 OLED. And here is a Grove touch module for controlling the whole system and the OLED to display the data. Seeeduino XIAO is completely compatible with Arduino, so this demo is based on Arduino IDE. For details, you can click here to install the board in the Arduino IDE.

Both of the Light sensor and OLED display can be driven by I2C interface, but they have different I2C addresses. So they are connected with the same of the Seeeduino XIAO’s I2C interface as slaves. There aren’t any pull-up resistances in Seeeduino XIAO’s Pins, as a matter of fact, the communication might be unstable between Seeeduino XIAO and two slave modules. For stability in the real use, I strongly recommended you to add pull-up resistances at the end of the I2C interfaces. DHT11 temperature sensor and Grove touch module simply connect with the Seeeduino XIAO by digital Pins. The overall hardware connection is really easy. Here is the Pinout of the Seeeduino XIAO.

As for the software code, you can find most of the modules getting started codes and libraries from the Seeed Wiki. It is worth to mention that the SSD1315 OLED Display uses the common U8g2 library which is a functional library to display multiple fonts and images. U8g2 library supports many types of OLED screens and a great many fonts libraries. The demo code is available as follows.

With the correct connection of jump wires and the code below, you can realize the demo of displaying the sensor values in the SSD1315 OLED display once you touch the touchpad, and the display will be cleared when you leave the touchpad. Due to the tiny size of Seeeduino XIAO, you are able to make it as a wearable environment detector to measure the values of temperature, humidity, and light everywhere you like.

Environmental sensors with Seeeduino XIAO

#include <Arduino.h>
#include <U8g2lib.h>
#include <Wire.h>
#include <Digital_Light_TSL2561.h>
#include <DHT.h>

#define DHTPIN    9
#define DHTTYPE DHT11   // DHT 11
#define TouchPin  8     // Grove touch module
U8G2_SSD1306_128X64_NONAME_1_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);// Init I2C U8g2 library
DHT dht(DHTPIN, DHTTYPE); // declare DHT11 sensor
uint16_t x1 = 0;

void setup()
{
  Wire.begin();
  Serial.begin(115200);
  TSL2561.init();
  dht.begin();
  u8g2.begin(); 
  pinMode(TouchPin, INPUT); 
 
}

void loop()
{  
         
   int sensorValue = digitalRead(TouchPin); // Read touch module value
   if(sensorValue == 1){  
   float temp_hum_val[2] = {0};
    // Reading temperature or humidity takes about 250 milliseconds!
    // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
    
    
    if(!dht.readTempAndHumidity(temp_hum_val)){
        Serial.print("Humidity: "); 
        Serial.print(temp_hum_val[0]);
        Serial.print(" %\t");
        Serial.print("Temperature: "); 
        Serial.print(temp_hum_val[1]);
        Serial.println(" *C");
    }
    else{
       Serial.println("Failed to get temprature and humidity value.");
    }
  uint16_t x2 = TSL2561.readVisibleLux(); // Read Light sensor value
  if(x1-x2>10000 || x2-x1>10000 )  // verify light sensor value
  {
    x1 = x1;
    }
  else {
    x1 = x2;
    } 
  Serial.print("The Light value is: ");
  Serial.println(x1);
  float h = dht.readHumidity(); // Read humidity value
  float t = dht.readTemperature(); // Read temperature value
  Serial.print("The Temperature is: ");
  Serial.println(t);
  Serial.print("The Humidity is: ");
  Serial.println(h);
  u8g2.firstPage(); // use U8g2 library to print data
  do {
    u8g2.setFont(u8g2_font_prospero_bold_nbp_tf);
    u8g2.setCursor(0, 20);
    u8g2.print(F("Light value: "));
    u8g2.print(x1);
    u8g2.print(F("LUX"));
    u8g2.setCursor(0,40);
    u8g2.print(F("Temperature: "));
    u8g2.print(t);
    u8g2.print(F("*C"));
    u8g2.setCursor(0,60);
    u8g2.print(F("Humidity: "));
    u8g2.print(h);
    u8g2.print(F("%"));
  } while ( u8g2.nextPage() );
//  delay(1000);
}
else {
 u8g2.clearDisplay(); // clear the OLED display
}
}