（Arduino)DHT11とDS1307のデータをSDカードに保存する（その２）

１．以前からの改善点

（Arduino)DHT11とDS1307のデータをSDカードに保存する（その１）で一応実現できたが、別のコードのほうが使い勝手が良い気がして、それを試してみた。

参考にしたのは、https://ht-deko.com/arduino/tiny_rtc.html

• PCの時刻と同期できるようになった。
• 保存ファイル名がyymdからyyyymmddになった。

２．コード（接続は前と異ならないので省略。）

#include <Wire.h>
#include <SimpleDHT.h>
#include "RTClib.h"
#include <SPI.h>
#include <SD.h>
#define RTC_address 0x68
DS1307 RTC;
int pinDHT11= 7;
SimpleDHT11 dht11(pinDHT11);
File myFile;

void setup () {
    Serial.begin(115200);
    Wire.begin();
    RTC.begin();
  if (! RTC.isrunning()) {
    Serial.println("RTC is NOT running!");
    // following line sets the RTC to the date & time this sketch was compiled
    //RTC.adjust(DateTime(__DATE__, __TIME__));
  }
  RTC.adjust(DateTime(__DATE__, __TIME__));
}

void loop () {
  byte temperature = 0;
  byte humidity = 0;
  int err = SimpleDHTErrSuccess;
  if ((err = dht11.read(&temperature, &humidity, NULL)) != SimpleDHTErrSuccess) {
    Serial.print("Read DHT11 failed, err="); Serial.print(SimpleDHTErrCode(err));
    Serial.print(","); Serial.println(SimpleDHTErrDuration(err)); delay(1000);
    return;
  }

    DateTime now = RTC.now();
  // Serial.print now for test.
  
      Serial.print(now.year(),DEC);
    //Serial.print('/');
    if ( now.month() < 10 ){
      Serial.print("0");
      Serial.print(now.month(), DEC);
    }else{
      Serial.print(now.month(), DEC);
    }
    //Serial.print('/');
    if( now.day() < 10 ){
      Serial.print("0");
      Serial.print(now.day(), DEC);
    }else{
      Serial.print(now.day(), DEC);
    }
    Serial.print("\t");
    Serial.print("計測時間:");
    Serial.print(now.hour(), DEC);
    Serial.print(':');
    Serial.print(now.minute(), DEC);
    Serial.print("\t");
    Serial.print("Temp:");
    Serial.print((int)temperature);
    Serial.print("C"); 
    Serial.print("\t"); 
    Serial.print("Humi:");
    Serial.print((int)humidity);
    Serial.println('%'); 
 
 
    //SD-card save
    if (!SD.begin(4)) {
    //Serial.println("initialization failed!");
    while (1);
     }
   //Serial.println("initialization done.");
   
 // file name  format yyyymmdd.csv
   if (( now.month() < 10 ) && ( now.day() < 10 )){
    myFile=SD.open( String(now.year(),DEC) + "0" + String(now.month(),DEC) + "0" + String(now.day(),DEC) + ".csv",FILE_WRITE); 
   }else if( now.month() < 10 ){
    myFile=SD.open( String(now.year(),DEC) + "0" + String(now.month(),DEC) +   String(now.day(),DEC) + ".csv",FILE_WRITE); 
   }else if( now.day() < 10) {
    myFile=SD.open( String(now.year(),DEC) + String(now.month(),DEC) + "0" + String(now.day(),DEC) + ".csv",FILE_WRITE);
   }else{
    myFile=SD.open( String(now.year(),DEC) + String(now.month(),DEC) + String(now.day(),DEC) + ".csv",FILE_WRITE);
   }
       
   if (myFile){
    //write contents: time, temperature and humidity,
    myFile.print(now.hour(),DEC);
    myFile.print(":");
    myFile.print(now.minute() ,DEC);
    myFile.print(",");
    myFile.print(temperature);
    myFile.print(",");
    myFile.println(humidity); 
    // close the file:
    myFile.close();
    //Serial.println("sdcard write done.");
    } else {
    // if the file didn't open, print an error:
    Serial.println("error opening file");
    Serial.print(now.year(),DEC);
    //Serial.print('/');
    if ( now.month() < 10 ){
     Serial.print("0");
     Serial.print(now.month(), DEC);
    }else{
     Serial.print(now.month(), DEC);
    }
    //Serial.print('/');
    if( now.day() < 10 ){
      Serial.print("0");
      Serial.print(now.day(), DEC);
    }else{
      Serial.print(now.day(), DEC);
    }
    Serial.print("\t");
    Serial.print(now.hour(), DEC);
    Serial.print(':');
    Serial.print(now.minute(), DEC);
    Serial.print(",");
    Serial.print((int)temperature); 
    Serial.print(","); 
    Serial.print((int)humidity); 
    Serial.println(",");
    //Serial.print(':');
    //Serial.print(now.second(), DEC);
    Serial.println("file write failed!");
    }

/* これ以降はテスト時に必要であっても、ファイルを開き読み込み、表示するのに時間がかかり、１日で１分以上の狂いが生じました。あくまでテスト時のものと考えたほうが良さそうです。
    
   if (( now.month() <10 ) && ( now.day() < 10 )){
       myFile=SD.open( String(now.year(),DEC) + "0" + String(now.month(),DEC) + "0" + String(now.day(),DEC) + ".csv"); 
    }else if( now.month() < 10 ){
       myFile=SD.open( String(now.year(),DEC) + "0" + String(now.month(),DEC) + String(now.day(),DEC) + ".csv"); 
    }else if( now.day() < 10) {
       myFile=SD.open( String(now.year(),DEC) + String(now.month(),DEC) + "0" + String(now.day(),DEC) + ".csv");
    }else{
       myFile=SD.open( String(now.year(),DEC) + String(now.month(),DEC) + String(now.day(),DEC) + ".csv");
    }
    if (myFile) {
      Serial.print("re-open file:");
      if (( now.month() < 10 ) && ( now.day() < 10 )){
        Serial.println ( String(now.year(),DEC) + "0" + String(now.month(),DEC) + "0" + String(now.day(),DEC) + ".csv"); 
       }else if( now.month() < 10 ){
        Serial.println( String(now.year(),DEC) + "0" + String(now.month(),DEC) + String(now.day(),DEC) + ".csv"); 
       }else if( now.day() < 10) {
        Serial.println( String(now.year(),DEC) + String(now.month(),DEC) + "0" + String(now.day(),DEC) + ".csv");
       }else{
        Serial.println( String(now.year(),DEC) + String(now.month(),DEC) + String(now.day(),DEC) + ".csv");
       }
      
        // read from the file until there's nothing else in it:
        while (myFile.available()) {
          Serial.write(myFile.read());
        }
        // close the file:
        myFile.close();
    } else {
    // if the file didn't open, print an error:
      Serial.println("error opening file");
    }
 --- ここまで ------ */
    
    delay(60000UL);
}

３．実行結果