Arduino read and write SD card module sensor data writing

foreword

For the specific SD card wiring, please refer to the Arduino read and write SD card module (to obtain SD card information).
This blog uses the temperature and humidity sensor DHT22 as an example. As for other sensors, you can draw inferences from one another.

hardware preparation

SD card module

temperature and humidity sensor DHT22

DHT22	Arduino
+	5V
S	7
GND	GND

code section

Temperature and humidity detection

#include <dht.h>
#define DHTPin 7 
dht DHT; 

void loop() {
    
    
  
  int readData = DHT.read22(DHTPin);
  float t = DHT.temperature; 
  float h = DHT.humidity;

  Serial.print("Temperature = ");
  Serial.print(t);
  Serial.print(" *C "); 
  Serial.print("    Humidity = ");
  Serial.print(h);
  Serial.println(" % ");

Create .txt file

myFile = SD.open("可以自主命名.txt", FILE_WRITE);

Function to write to SD card: "myFile"

if (myFile) {
    
      
    myFile.print("Temperature = "); 
    myFile.print(t);
    myFile.print(",");  
    myFile.print("    Humidity = ");  
    myFile.println(h);
    myFile.close(); //结束文件记录
  }

Determine if the file can be opened

else {
    
    
    Serial.println("error opening data.txt");
  }

full code

#include <SD.h>
#include <SPI.h>
#include <dht.h>
#define DHTPin 7 
dht DHT; 
File myFile;
int pinCS = 4; 
void setup() {
    
    
   
  Serial.begin(9600);
  pinMode(pinCS, OUTPUT);
  
  // SD Card Initialization
  if (SD.begin())
  {
    
    
    Serial.println("SD card is ready to use.");
  } else
  {
    
    
    Serial.println("SD card initialization failed");
    return;
  }
}
void loop() {
    
    
  
  int readData = DHT.read22(DHTPin);
  float t = DHT.temperature; 
  float h = DHT.humidity;

  Serial.print("Temperature = ");
  Serial.print(t);
  Serial.print(" *C "); 
  Serial.print("    Humidity = ");
  Serial.print(h);
  Serial.println(" % ");

  myFile = SD.open("data.txt", FILE_WRITE);
  if (myFile) {
    
      
    myFile.print("Temperature = "); 
    myFile.print(t);
    myFile.print(",");  
    myFile.print("    Humidity = ");  
    myFile.println(h);
    myFile.close(); // close the file
  }
  else {
    
    
    Serial.println("error opening data.txt");
  }
  delay(500);  
}

renderings

Check that the DATA.txt

data in the SD card has been successfully written! ! !

Postscript supplement

We can use the data recorded in the SD card to draw tables and line graphs, etc. Good luck


in drawing it into a line graph !

! !