[EPS8266] ESP 12E 傳送PH以及溫度資料到ThingSpeak

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簡介

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ESP 12E 算是EPS 8266 系統列很牛的晶片，也提供比較多的腳位，

找把它拿來替代Arduino取得魚缸中的資料，顯示在LCD上，並傳到ThingSpeak。



PH 2的原因是因為他爬升到穩定需要一點時間，但我20秒才讓他取一次值，

他需要取6次，去頭去尾取中間的平均值，它的取值時間不建議小於800ms，

一般來說校正後放入水中要達到穩要幾分鐘，例如海水缸，它會從0慢慢的爬到

8.x，達到穩定後，水中的PH值改變時，它就能夠快速反應。（當然你如果從8變到10,

還是要爬很久，但如果只是0.X的變化是很快的）

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材料

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ESP 12E

PH meter

DS18b20 (防水版本）

1602 I2C LCD

杜邦線

麵包板（小）

麵包板電源模組

DC 9V電源供應器

USB to TTL （燒錄程式碼用）

Wi－Fi  AP （讓ESP 12 可以傳資料到ThingSpeak）

ThingSpeak Account

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接線

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ESP 12E    麵包板      PH meter   DS18b20     LCD

VCC          3.3V                                                  

GND         GND         GND           GND            GND    USB to TTL

CH＿PID   3.3V

GPIO 14                                         Data

GPIO 4                                                                  SDA

GPIO 5                                                                  SCL

ADC (A0)                  Data                            

                     5V           VCC          VCC             VCC

－－－－－－－－－－－－以下是燒錄時才要加的－－－－－－
RX                                                                                       TX                                                                                                                
TX                                                                                       RX

GND      GND

GPIO0   GND

這邊有2個重點，

(1)DS18b20需要搭配1個4.7K電阻，詳情請參考[Arduino]DS18B20 防水溫度計
                         
(2)ESP 12 E 的ADC，支援的類比為10bit，但電壓範為是0~1V，這點

比較特別，一開始輸入2V怎麼都輸出1024，查了很多文才發現這個重點。

When your potentiometer is near 0V it prints 0 and when it reaches 1V it should print 1024.

資料來源：

http://randomnerdtutorials.com/esp8266-adc-reading-analog-values-with-nodemcu/

但PH meter output 為0~5V analog data, 所以我只好拿起5顆10K電阻做分壓，

因為我用的不是精密電阻，10顆幾塊錢那種，所以我必須再重新校正一次PH meter，

因為電阻會有誤差，然候這樣子會導致你拿到的可能不是1/5的電壓值，所以重新依據

目前的狀況校正。（手邊沒有其他東西可用時才用這招，不是個好方法）

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ThingSpeak

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建立一個CHANNEL，使用2個欄位如下所示，並且把API KEY貼到程式碼中。

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程式碼

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#include <LiquidCrystal_I2C.h>
#include <Wire.h>  
#include <ESP8266WiFi.h>
#include <OneWire.h>
#define SensorPin A0           //pH meter Analog output to Arduino Analog Input 0
#define Offset 0.42           //deviation compensate
#define samplingInterval 20
#define printInterval 800
#define ArrayLenth  40    //times of collection
int pHArray[ArrayLenth];   //Store the average value of the sensor feedback
int pHArrayIndex=0;   
OneWire  ds(14);  // on pin 14 (a 4.7K resistor is necessary)
// replace with your channel’s thingspeak API key,
String apiKey = "your ThingSpeak API Key";
const char* ssid = "your ssid";
const char* password = "your password";

const char* server = "api.thingspeak.com";
LiquidCrystal_I2C lcd(0x27,16,2); // Check I2C address of LCD, normally 0x27 or 0x3F
static const byte degrees_glyph[] = { 0x00, 0x07, 0x05, 0x07, 0x00 };
WiFiClient client;


void setup()  {
lcd.begin(4,5);      // In ESP8266-01, SDA=0, SCL=2               
lcd.backlight();
// Register the custom symbol...
Serial.begin(115200);
delay(10);
Serial.println();
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);

WiFi.begin(ssid, password);

while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
Serial.println("");
Serial.println("WiFi connected");
}

void loop()  {
byte i;
byte present = 0;
byte type_s;
byte data[12];
byte addr[8];
float celsius, fahrenheit;
int h=20;

if ( !ds.search(addr)) {
    Serial.println("No more addresses.");
    Serial.println();
    ds.reset_search();
    delay(250);
    return;
  }
  
  Serial.print("ROM =");
  for( i = 0; i < 8; i++) {
    Serial.write(' ');
    Serial.print(addr[i], HEX);
  }

  if (OneWire::crc8(addr, 7) != addr[7]) {
      Serial.println("CRC is not valid!");
      return;
  }
  Serial.println();
 
  // the first ROM byte indicates which chip
  switch (addr[0]) {
    case 0x10:
      Serial.println("  Chip = DS18S20");  // or old DS1820
      type_s = 1;
      break;
    case 0x28:
      Serial.println("  Chip = DS18B20");
      type_s = 0;
      break;
    case 0x22:
      Serial.println("  Chip = DS1822");
      type_s = 0;
      break;
    default:
      Serial.println("Device is not a DS18x20 family device.");
      return;
  } 

  ds.reset();
  ds.select(addr);
  ds.write(0x44, 1);        // start conversion, with parasite power on at the end
  
  delay(1000);     // maybe 750ms is enough, maybe not
  // we might do a ds.depower() here, but the reset will take care of it.
  
  present = ds.reset();
  ds.select(addr);    
  ds.write(0xBE);         // Read Scratchpad

  Serial.print("  Data = ");
  Serial.print(present, HEX);
  Serial.print(" ");
  for ( i = 0; i < 9; i++) {           // we need 9 bytes
    data[i] = ds.read();
    Serial.print(data[i], HEX);
    Serial.print(" ");
  }
  Serial.print(" CRC=");
  Serial.print(OneWire::crc8(data, 8), HEX);
  Serial.println();

  // Convert the data to actual temperature
  // because the result is a 16 bit signed integer, it should
  // be stored to an "int16_t" type, which is always 16 bits
  // even when compiled on a 32 bit processor.
  int16_t raw = (data[1] << 8) | data[0];
  if (type_s) {
    raw = raw << 3; // 9 bit resolution default
    if (data[7] == 0x10) {
      // "count remain" gives full 12 bit resolution
      raw = (raw & 0xFFF0) + 12 - data[6];
    }
  } else {
    byte cfg = (data[4] & 0x60);
    // at lower res, the low bits are undefined, so let's zero them
    if (cfg == 0x00) raw = raw & ~7;  // 9 bit resolution, 93.75 ms
    else if (cfg == 0x20) raw = raw & ~3; // 10 bit res, 187.5 ms
    else if (cfg == 0x40) raw = raw & ~1; // 11 bit res, 375 ms
    //// default is 12 bit resolution, 750 ms conversion time
  }
  celsius = (float)raw / 16.0;
  fahrenheit = celsius * 1.8 + 32.0;
  Serial.print("  Temperature = ");
  Serial.print(celsius);
  Serial.print(" Celsius, ");
  Serial.print(fahrenheit);
  Serial.println(" Fahrenheit");
  static unsigned long samplingTime = millis();
  static unsigned long printTime = millis();
  static float pHValue,voltage;
  if(millis()-samplingTime > samplingInterval)
  {
      pHArray[pHArrayIndex++]=analogRead(SensorPin);
      if(pHArrayIndex==ArrayLenth)pHArrayIndex=0;
      voltage = avergearray(pHArray, ArrayLenth)*5.0/1024;
      pHValue = 3.5*voltage+Offset;
      samplingTime=millis();
  }
  if(millis() - printTime > printInterval)   //Every 800 milliseconds, print a numerical, convert the state of the LED indicator
  {
    Serial.print("Voltage:");
    Serial.print(voltage,2);
    Serial.print("    pH value: ");
    Serial.println(pHValue,2);
    printTime=millis();
  }


if (client.connect(server,80)) { // "184.106.153.149" or api.thingspeak.com
String postStr = apiKey;
postStr +="&field1=";
postStr += String(celsius);
postStr +="&field2=";
postStr += String(pHValue);
postStr += "\r\n\r\n";

client.print("POST /update HTTP/1.1\n");
client.print("Host: api.thingspeak.com\n");
client.print("Connection: close\n");
client.print("X-THINGSPEAKAPIKEY: "+apiKey+"\n");
client.print("Content-Type: application/x-www-form-urlencoded\n");
client.print("Content-Length: ");
client.print(postStr.length());
client.print("\n\n");
client.print(postStr);
lcd.setCursor(0, 0);
lcd.print("Temperature:");
lcd.print(celsius,1);
lcd.setCursor(0, 1);
lcd.print("PH Value:");
lcd.print(pHValue,1);
Serial.print("Temperature: ");
Serial.print(celsius);
Serial.print("PH: ");
Serial.print(pHValue);
Serial.println("send to Thingspeak");
}
client.stop();

Serial.println("Waiting…");
// thingspeak needs minimum 15 sec delay between updates
delay(20000);
}
double avergearray(int* arr, int number){
  int i;
  int max,min;
  double avg;
  long amount=0;
  if(number<=0){
    Serial.println("Error number for the array to avraging!/n");
    return 0;
  }
  if(number<5){   //less than 5, calculated directly statistics
    for(i=0;i<number;i++){
      amount+=arr[i];
    }
    avg = amount/number;
    return avg;
  }else{
    if(arr[0]<arr[1]){
      min = arr[0];max=arr[1];
    }
    else{
      min=arr[1];max=arr[0];
    }
    for(i=2;i<number;i++){
      if(arr[i]<min){
        amount+=min;        //arr<min
        min=arr[i];
      }else {
        if(arr[i]>max){
          amount+=max;    //arr>max
          max=arr[i];
        }else{
          amount+=arr[i]; //min<=arr<=max
        }
      }//if
    }//for
    avg = (double)amount/(number-2);
  }//if
  return avg;
}

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執行畫面

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PH 尚在未穩定狀態，所以2.9 並不正確，到達穩定要一點時間 ，目前程式每次執行時間

間隔20秒，對PH取值而言太久，需要再做調整，PH到達穩定約10~20分鐘。

下圖是ThingSpeak上的資料（隔了一天）。