# Arduino 溫濕度感測器 DHT11 測試
那時我正在忙著焊我的 IOT 模組, 現在萬事俱備, 於是找出 DHT11 來重新做一次溫溼度實驗, 當然套用為這塊 IOT 模組寫的程式架構. 首先到 Github 下載 Adafruit 的 DHT11/22 函式庫到 Arduino 安裝目錄下的 library 資料夾下 (然後 Arduino IDE 必須重開才抓得到) :
# adafruit/DHT-sensor-library
然後把 DHT11 插到麵包板上, VCC 與 DATA 腳之間插上 10K 電阻, VCC 與 GND 插個 0.1uF 電容 (104), 再將 DATA 腳接到 Arduino 的 D2 腳, 然後將 IOT 模組設定好要連線的 AP, 切到工作模式重開機, 將下列程式上傳即可 :
測試 1 :
#include <SoftwareSerial.h>
#define DEBUG true
//-----application include & def listed HERE-----
#include "DHT.h"
#define DHTPIN 2
#define DHTTYPE DHT11
//system use please do not edit
SoftwareSerial esp8266(7,8); //(RX,TX)
const int SW_PIN=4; //Pin to switch configuration or working mode
const int MAX_PAGE_NAME_LEN=48; //buffer size
char buffer[MAX_PAGE_NAME_LEN + 1]; //store page_name/ssid/pwd
int mode; //store current mode(LOW=wifi setup, HIGH=working)
//-----application global variables listed HERE-----
DHT dht(DHTPIN, DHTTYPE); // Initialize DHT sensor
void setup() {
//system use please do not edit
Serial.begin(9600);
esp8266.begin(9600);
sendData("AT+RST\r\n",2000,DEBUG); // reset ESP8266
pinMode(SW_PIN, INPUT);
mode=digitalRead(SW_PIN);
sendData("AT+GMR\r\n",1000,DEBUG);
if (mode==LOW) { //setup mode : for wifi configuration
sendData("AT+CWMODE=3\r\n",1000,DEBUG); //configure as access point
sendData("AT+CIPMUX=1\r\n",1000,DEBUG); //enable multiple connections
sendData("AT+CIPSERVER=1,80\r\n",2000,DEBUG); //turn on server 80 port
}
else { //working mode : for running application
sendData("AT+CWMODE=1\r\n",1000,DEBUG); //configure as a station
delay(3000); //wait for wifi connection to get local ip
}
sendData("AT+CIFSR\r\n",1000,DEBUG); //get ip address
//-----application setup codes listed HERE-----
Serial.println("DHT11 test");
dht.begin();
}
void loop() {
if (mode==LOW) {setupWifi();} //system use please do not edit
else { //-----application loop codes listed HERE-----
float h=dht.readHumidity();
float t=dht.readTemperature();
float f=dht.readTemperature(true);
if (isnan(h) || isnan(t) || isnan(f)) {
Serial.println("Failed to read from DHT sensor!");
return;
}
Serial.print("Humidity: ");
Serial.print(h);
Serial.print("%\t");
Serial.print("Temperature: ");
Serial.print(t);
Serial.print("*C\t");
Serial.print(f);
Serial.print("*F\n");
delay(2000);
}
}
void setupWifi() { //system use please do not edit
if (esp8266.available()) { // check if the esp is sending a message
if (esp8266.find("+IPD,")) {
delay(1000);
//esp8266 link response : +IPD,0,498:GET / HTTP/1.1
//retrieve connection ID from response (0~4, after "+IPD,")
int connectionId=esp8266.read()-48; //from ASCII to number
//subtract 48 because read() returns ASCII decimal value
//and in ASCII, "0" (the first decimal number) starts at 48
if (esp8266.find("GET /")) { //retrieve page name (router)
memset(buffer, 0, sizeof(buffer)); //clear buffer (all set to 0)
if (esp8266.readBytesUntil('/', buffer, sizeof(buffer))) {
if (strcmp(buffer, "update") == 0) { //update wifi
//"?ssid=aaa&pwd=bbb HTTP/1.1"
esp8266.find("?ssid="); //skip ssid token
memset(buffer, 0, sizeof(buffer)); //clear buffer (all set to 0)
esp8266.readBytesUntil('&', buffer, sizeof(buffer)); //retrieve ssid
String ssid=buffer;
esp8266.find("pwd="); //skip pwd token
memset(buffer, 0, sizeof(buffer)); //clear buffer (all set to 0)
esp8266.readBytesUntil(' ', buffer, sizeof(buffer)); //retrieve pwd
String pwd=buffer;
//configure as a station
String res=sendData("AT+CWJAP=\"" + ssid + "\",\"" + pwd + "\"\r\n",6000,DEBUG);
//show setup result
String webpage="<html>Wifi setup ";
if (res.indexOf("OK") != -1) {webpage += "OK!</html>";}
else {webpage += "Failed!</html>";}
String cipSend="AT+CIPSEND=";
cipSend += connectionId;
cipSend += ",";
cipSend +=webpage.length();
cipSend +="\r\n";
sendData(cipSend,1000,DEBUG);
sendData(webpage,2000,DEBUG);
String closeCommand = "AT+CIPCLOSE=";
closeCommand+=connectionId; // append connection id
closeCommand+="\r\n";
sendData(closeCommand,3000,DEBUG);
}
else { //show setup page
String webpage="<html><form method=get action='/update/'>SSID ";
webpage += "<input name=ssid type=text><br>";
String cipSend = "AT+CIPSEND=";
cipSend += connectionId;
cipSend += ",";
cipSend +=webpage.length();
cipSend +="\r\n";
sendData(cipSend,1000,DEBUG);
sendData(webpage,2000,DEBUG);
webpage="PWD <input name=pwd type=text> ";
cipSend = "AT+CIPSEND=";
cipSend += connectionId;
cipSend += ",";
cipSend +=webpage.length();
cipSend +="\r\n";
sendData(cipSend,1000,DEBUG);
sendData(webpage,2000,DEBUG);
webpage="<input type=submit value=Connect></form></html>";
cipSend = "AT+CIPSEND=";
cipSend += connectionId;
cipSend += ",";
cipSend +=webpage.length();
cipSend +="\r\n";
sendData(cipSend,1000,DEBUG);
sendData(webpage,2000,DEBUG);
String closeCommand = "AT+CIPCLOSE=";
closeCommand+=connectionId; // append connection id
closeCommand+="\r\n";
sendData(closeCommand,3000,DEBUG);
}
}
}
}
}
}
//system use please do not edit
String sendData(String command, const int timeout, boolean debug) {
String response="";
esp8266.print(command); // send the read character to the esp8266
long int time=millis();
while ((time+timeout) > millis()) {
while(esp8266.available()) {
// The esp has data so display its output to the serial window
char c=esp8266.read(); // read the next character.
response += c;
}
}
if (debug) {Serial.print(response);}
return response;
}
上面測試 1 只是將自 DHT11 讀取的溫溼度數值輸出到序列埠而已, 並未使用到 ESP8266 的連網功能. 序列埠監控視窗擷取訊息如下 :
AT+RST
OK
bB�鑭b禔S��"軫B�侒��餾�
[System Ready, Vendor:www.ai-thinker.com]
AT+GMR
0018000902
OK
AT+CWMODE=1
no change
AT+CIFSR
192.168.43.111
OK
DHT11 test
Humidity: 47.00% Temperature: 27.00*C 80.60*F
Humidity: 48.00% Temperature: 27.00*C 80.60*F
Humidity: 49.00% Temperature: 26.00*C 78.80*F
Humidity: 51.00% Temperature: 27.00*C 80.60*F
Humidity: 47.00% Temperature: 27.00*C 80.60*F
Humidity: 47.00% Temperature: 27.00*C 80.60*F
Humidity: 47.00% Temperature: 27.00*C 80.60*F
...
可見使用 Adafruit 的函式庫沒問題呀! 接下來參考之前寫的 Thingspeak 物聯網伺服器實驗, 將所量取的溫溼度數據上傳到 Thingspeak 伺服器上. 在這之前必須去申請一個 Thingspeak 帳號, 取得一個寫入的 API KEY, 參考下面這篇的說明 :
# ESP8266 WiFi 模組與 Arduino 連線測試 (Thingspeak)
完整程式如下 :
測試 2 :
#include <SoftwareSerial.h>
#define DEBUG true
//-----application include & def listed HERE-----
#include "DHT.h"
#define DHTPIN 2
#define DHTTYPE DHT11
//system use please do not edit
SoftwareSerial esp8266(7,8); //(RX,TX)
const int SW_PIN=4; //Pin to switch configuration or working mode
const int MAX_PAGE_NAME_LEN=48; //buffer size
char buffer[MAX_PAGE_NAME_LEN + 1]; //store page_name/ssid/pwd
int mode; //store current mode(LOW=wifi setup, HIGH=working)
//-----application global variables listed HERE-----
DHT dht(DHTPIN, DHTTYPE); // Initialize DHT sensor
String api_key="NO5N8C7T2KINFCQE"; //Thingspeak API Write Key
void setup() {
//system use please do not edit
Serial.begin(9600);
esp8266.begin(9600);
sendData("AT+RST\r\n",2000,DEBUG); // reset ESP8266
pinMode(SW_PIN, INPUT);
mode=digitalRead(SW_PIN);
sendData("AT+GMR\r\n",1000,DEBUG);
if (mode==LOW) { //setup mode : for wifi configuration
sendData("AT+CWMODE=3\r\n",1000,DEBUG); //configure as access point
sendData("AT+CIPMUX=1\r\n",1000,DEBUG); //enable multiple connections
sendData("AT+CIPSERVER=1,80\r\n",2000,DEBUG); //turn on server 80 port
}
else { //working mode : for running application
sendData("AT+CWMODE=1\r\n",1000,DEBUG); //configure as a station
delay(3000); //wait for wifi connection to get local ip
}
sendData("AT+CIFSR\r\n",1000,DEBUG); //get ip address
//-----application setup codes listed HERE-----
Serial.println("DHT11 test");
dht.begin();
}
void loop() {
if (mode==LOW) {setupWifi();} //system use please do not edit
else { //-----application loop codes listed HERE-----
float h=dht.readHumidity(); //get humidity from DHT11
float c=dht.readTemperature(); //get temperature (C) from DHT11
float f=dht.readTemperature(true); //get temperature (F) from DHT11
//create data string to Thingspeak
String data="GET /update?api_key=" + api_key + "&field1=" + (String)c +
"&field2=" + (String)f + "&field3=" + (String)h + "\r\n";
String cmd="AT+CIPSTART=\"TCP\",\"184.106.153.149\",80\r\n";
sendData(cmd, 1000, DEBUG);
cmd="AT+CIPSEND=";
cmd += data.length();
cmd += "\r\n";
sendData(cmd,1000,DEBUG);
String res=sendData(data, 2000, DEBUG);
res.replace("\r\n",""); //remove all line terminator
if (res.indexOf("Unlink") == -1) { //if no auto unlink
sendData("AT+CIPCLOSE\r\n",2000,DEBUG); //close session
}
delay(5000);
}
}
void setupWifi() { //system use please do not edit
if (esp8266.available()) { // check if the esp is sending a message
if (esp8266.find("+IPD,")) {
delay(1000);
//esp8266 link response : +IPD,0,498:GET / HTTP/1.1
//retrieve connection ID from response (0~4, after "+IPD,")
int connectionId=esp8266.read()-48; //from ASCII to number
//subtract 48 because read() returns ASCII decimal value
//and in ASCII, "0" (the first decimal number) starts at 48
if (esp8266.find("GET /")) { //retrieve page name (router)
memset(buffer, 0, sizeof(buffer)); //clear buffer (all set to 0)
if (esp8266.readBytesUntil('/', buffer, sizeof(buffer))) {
if (strcmp(buffer, "update") == 0) { //update wifi
//"?ssid=aaa&pwd=bbb HTTP/1.1"
esp8266.find("?ssid="); //skip ssid token
memset(buffer, 0, sizeof(buffer)); //clear buffer (all set to 0)
esp8266.readBytesUntil('&', buffer, sizeof(buffer)); //retrieve ssid
String ssid=buffer;
esp8266.find("pwd="); //skip pwd token
memset(buffer, 0, sizeof(buffer)); //clear buffer (all set to 0)
esp8266.readBytesUntil(' ', buffer, sizeof(buffer)); //retrieve pwd
String pwd=buffer;
//configure as a station
String res=sendData("AT+CWJAP=\"" + ssid + "\",\"" + pwd + "\"\r\n",6000,DEBUG);
//show setup result
String webpage="<html>Wifi setup ";
if (res.indexOf("OK") != -1) {webpage += "OK!</html>";}
else {webpage += "Failed!</html>";}
String cipSend="AT+CIPSEND=";
cipSend += connectionId;
cipSend += ",";
cipSend +=webpage.length();
cipSend +="\r\n";
sendData(cipSend,1000,DEBUG);
sendData(webpage,2000,DEBUG);
String closeCommand = "AT+CIPCLOSE=";
closeCommand+=connectionId; // append connection id
closeCommand+="\r\n";
sendData(closeCommand,3000,DEBUG);
}
else { //show setup page
String webpage="<html><form method=get action='/update/'>SSID ";
webpage += "<input name=ssid type=text><br>";
String cipSend = "AT+CIPSEND=";
cipSend += connectionId;
cipSend += ",";
cipSend +=webpage.length();
cipSend +="\r\n";
sendData(cipSend,1000,DEBUG);
sendData(webpage,2000,DEBUG);
webpage="PWD <input name=pwd type=text> ";
cipSend = "AT+CIPSEND=";
cipSend += connectionId;
cipSend += ",";
cipSend +=webpage.length();
cipSend +="\r\n";
sendData(cipSend,1000,DEBUG);
sendData(webpage,2000,DEBUG);
webpage="<input type=submit value=Connect></form></html>";
cipSend = "AT+CIPSEND=";
cipSend += connectionId;
cipSend += ",";
cipSend +=webpage.length();
cipSend +="\r\n";
sendData(cipSend,1000,DEBUG);
sendData(webpage,2000,DEBUG);
String closeCommand = "AT+CIPCLOSE=";
closeCommand+=connectionId; // append connection id
closeCommand+="\r\n";
sendData(closeCommand,3000,DEBUG);
}
}
}
}
}
}
//system use please do not edit
String sendData(String command, const int timeout, boolean debug) {
String response="";
esp8266.print(command); // send the read character to the esp8266
long int time=millis();
while ((time+timeout) > millis()) {
while(esp8266.available()) {
// The esp has data so display its output to the serial window
char c=esp8266.read(); // read the next character.
response += c;
}
}
if (debug) {Serial.print(response);}
return response;
}
這裡板子開機後進入工作模式, ESP8266 會自動連上 AP, 我們只要使用 AT+CIPSTART 指令與 Thingspeak 伺服器 (使用 IP=184.106.153.149 或者網址 api.thingspeak.com) 建立一個 TCP 連線 :
AT+CIPSTART="TCP","184.106.153.149",80
或者
AT+CIPSTART="TCP","api.thingspeak.com",80
然後製作 HTTP 的 GET 方法字串, 裡面帶上我們從 DHT11 取得的溫溼度, 其格式如下 :
GET update?api_key=寫入金鑰&欄位1=數值1&欄位2=數值2&欄位3=數值3
其中的欄位名稱我在 Thingspeak 分別為攝氏溫度, 華氏溫度, 以及濕度取名為 field1, field2, 與 field3, 因此傳送出去的字串是向下面這樣 :
GET /update?api_key=NO5N8C7T2KINFCQE&field1=29.00&field2=84.20&field3=73.00
然後用 AT+CIPSEND 指令告訴 ESP8266 要傳送的 GET 字串的長度 :
AT+CIPSEND=GET 字串長度
上面的程式中我是用字串的 length() 函式來取得字串長度, 注意, 因為 length() 傳回的是整數, 所以必須用 (String) 強制轉型 :
cmd="AT+CIPSEND=" + cmd + (String)data.length() + "\r\n";
不過上面程式中我是一個一個用 += 串接, 單獨時會自動轉型.
最後將 GET 字串當資料傳給伺服器, 其 API 就會將溫溼度數據寫入物聯網伺服器的資料庫了. 通常 Thingspeak 伺服器在收到我們傳送的資料後會自動拆除 TCP 連線 (ESP8266 會回應 Unlink), 但偶而不會, 因此我參考之前從 foxhollow 擷取網路時間的做法, 從 sendData() 函式的傳回字串中分析是否有收到 Unlink, 沒有的話才對 ESP8266 下 AT+CIPCLOSE 關閉 TCP 連線, 有的話就不需要. 其實一律都下 AT+CIPCLOSE 也沒關係, 只是在有自動 Unlink 情況時, 再下 AT+CIPCLOSE 會回應 Error 而已. 參考 :
# 從 HTTP 網頁伺服器獲取時間訊息的方法
序列埠監控視窗攫取之訊息如下 :
AT+RST
OK
bB�鑭b禔R��"墽B�侒��餾�
[System Ready, Vendor:www.ai-thinker.com]
AT+GMR
0018000902
OK
AT+CWMODE=1
no change
AT+CIFSR
192.168.2.111
OK
DHT11 test
AT+CIPSTART="TCP","184.106.153.149",80
AT+CIPSEND=77
busy p...
OK
Linked
GET /update?api_key=NO5N8C7T2KINFCQE&field1=30.00&field2=86.00&
ERROR
AT+CIPCLOSE
OK
Unlink
AT+CIPSTART="TCP","184.106.153.149",80
OK
Linked
AT+CIPSEND=77
> GET /update?api_key=NO5N8C7T2KINFCQE&field1=30.00&field2=86.00&
SEND OK
+IPD,5:19839
OK
OK
Unlink
AT+CIPSTART="TCP","184.106.153.149",80
OK
Linked
AT+CIPSEND=77
> GET /update?api_key=NO5N8C7T2KINFCQE&field1=30.00&field2=86.00&
SEND OK
+IPD,1:0
OK
OK
Unlink
AT+CIPSTART="TCP","184.106.153.149",80
OK
Linked
AT+CIPSEND=77
> GET /update?api_key=NO5N8C7T2KINFCQE&field1=30.00&field2=86.00&
SEND OK
+IPD,5:19840
OK
OK
Unlink
接下來測試 3 就要加入一個光敏電阻當光度計了, 參考去年 10 月寫的這篇 :
# Arduino 光敏電阻測試
我在麵包板上 DHT11 旁邊插上一個 10K 電阻與光敏電阻串聯, 光敏電阻接地, 10K 電阻接 VCC, 中間接到 Arduino 的 A0 腳 :
程式如下 :
測試 3 :
#include <SoftwareSerial.h>
#define DEBUG true
//-----application include & def listed HERE-----
#include "DHT.h"
#define DHTPIN 2
#define DHTTYPE DHT11
//system use please do not edit
SoftwareSerial esp8266(7,8); //(RX,TX)
const int SW_PIN=4; //Pin to switch configuration or working mode
const int MAX_PAGE_NAME_LEN=48; //buffer size
char buffer[MAX_PAGE_NAME_LEN + 1]; //store page_name/ssid/pwd
int mode; //store current mode(LOW=wifi setup, HIGH=working)
//-----application global variables listed HERE-----
DHT dht(DHTPIN, DHTTYPE); // Initialize DHT sensor
String api_key="NO5N8C7T2KINFCQE"; //Thingspeak API Write Key
void setup() {
//system use please do not edit
Serial.begin(9600);
esp8266.begin(9600);
sendData("AT+RST\r\n",2000,DEBUG); // reset ESP8266
pinMode(SW_PIN, INPUT);
mode=digitalRead(SW_PIN);
sendData("AT+GMR\r\n",1000,DEBUG);
if (mode==LOW) { //setup mode : for wifi configuration
sendData("AT+CWMODE=3\r\n",1000,DEBUG); //configure as access point
sendData("AT+CIPMUX=1\r\n",1000,DEBUG); //enable multiple connections
sendData("AT+CIPSERVER=1,80\r\n",2000,DEBUG); //turn on server 80 port
}
else { //working mode : for running application
sendData("AT+CWMODE=1\r\n",1000,DEBUG); //configure as a station
delay(3000); //wait for wifi connection to get local ip
}
sendData("AT+CIFSR\r\n",1000,DEBUG); //get ip address
//-----application setup codes listed HERE-----
Serial.println("DHT11 test");
dht.begin();
}
void loop() {
if (mode==LOW) {setupWifi();} //system use please do not edit
else { //-----application loop codes listed HERE-----
float h=dht.readHumidity(); //get humidity from DHT11
float c=dht.readTemperature(); //get temperature (C) from DHT11
float f=dht.readTemperature(true); //get temperature (F) from DHT11
int cds=analogRead(A0); //get cds voltage (0~5V to 0~1023 dark)
int l=100-map(cds,0,1023,0,100); //map 0~1023(dark) to 0(dark)~100%
//create data string to Thingspeak
String data="GET /update?api_key=" + api_key + "&field1=" + (String)c +
"&field2=" + (String)f + "&field3=" + (String)h + "&field4=" +
(String)l + "\r\n";
Serial.println(data);
String cmd="AT+CIPSTART=\"TCP\",\"184.106.153.149\",80\r\n";
sendData(cmd, 1000, DEBUG);
cmd="AT+CIPSEND=" + (String)data.length() + "\r\n";
sendData(cmd,1000,DEBUG);
String res=sendData(data, 2000, DEBUG);
res.replace("\r\n",""); //remove all line terminator
if (res.indexOf("Unlink") == -1) { //if no auto unlink
sendData("AT+CIPCLOSE\r\n",2000,DEBUG); //close session
}
delay(5000);
}
}
void setupWifi() { //system use please do not edit
if (esp8266.available()) { // check if the esp is sending a message
if (esp8266.find("+IPD,")) {
delay(1000);
//esp8266 link response : +IPD,0,498:GET / HTTP/1.1
//retrieve connection ID from response (0~4, after "+IPD,")
int connectionId=esp8266.read()-48; //from ASCII to number
//subtract 48 because read() returns ASCII decimal value
//and in ASCII, "0" (the first decimal number) starts at 48
if (esp8266.find("GET /")) { //retrieve page name (router)
memset(buffer, 0, sizeof(buffer)); //clear buffer (all set to 0)
if (esp8266.readBytesUntil('/', buffer, sizeof(buffer))) {
if (strcmp(buffer, "update") == 0) { //update wifi
//"?ssid=aaa&pwd=bbb HTTP/1.1"
esp8266.find("?ssid="); //skip ssid token
memset(buffer, 0, sizeof(buffer)); //clear buffer (all set to 0)
esp8266.readBytesUntil('&', buffer, sizeof(buffer)); //retrieve ssid
String ssid=buffer;
esp8266.find("pwd="); //skip pwd token
memset(buffer, 0, sizeof(buffer)); //clear buffer (all set to 0)
esp8266.readBytesUntil(' ', buffer, sizeof(buffer)); //retrieve pwd
String pwd=buffer;
//configure as a station
String res=sendData("AT+CWJAP=\"" + ssid + "\",\"" + pwd + "\"\r\n",6000,DEBUG);
//show setup result
String webpage="<html>Wifi setup ";
if (res.indexOf("OK") != -1) {webpage += "OK!</html>";}
else {webpage += "Failed!</html>";}
String cipSend="AT+CIPSEND=";
cipSend += connectionId;
cipSend += ",";
cipSend +=webpage.length();
cipSend +="\r\n";
sendData(cipSend,1000,DEBUG);
sendData(webpage,2000,DEBUG);
String closeCommand = "AT+CIPCLOSE=";
closeCommand+=connectionId; // append connection id
closeCommand+="\r\n";
sendData(closeCommand,3000,DEBUG);
}
else { //show setup page
String webpage="<html><form method=get action='/update/'>SSID ";
webpage += "<input name=ssid type=text><br>";
String cipSend = "AT+CIPSEND=";
cipSend += connectionId;
cipSend += ",";
cipSend +=webpage.length();
cipSend +="\r\n";
sendData(cipSend,1000,DEBUG);
sendData(webpage,2000,DEBUG);
webpage="PWD <input name=pwd type=text> ";
cipSend = "AT+CIPSEND=";
cipSend += connectionId;
cipSend += ",";
cipSend +=webpage.length();
cipSend +="\r\n";
sendData(cipSend,1000,DEBUG);
sendData(webpage,2000,DEBUG);
webpage="<input type=submit value=Connect></form></html>";
cipSend = "AT+CIPSEND=";
cipSend += connectionId;
cipSend += ",";
cipSend +=webpage.length();
cipSend +="\r\n";
sendData(cipSend,1000,DEBUG);
sendData(webpage,2000,DEBUG);
String closeCommand = "AT+CIPCLOSE=";
closeCommand+=connectionId; // append connection id
closeCommand+="\r\n";
sendData(closeCommand,3000,DEBUG);
}
}
}
}
}
}
//system use please do not edit
String sendData(String command, const int timeout, boolean debug) {
String response="";
esp8266.print(command); // send the read character to the esp8266
long int time=millis();
while ((time+timeout) > millis()) {
while(esp8266.available()) {
// The esp has data so display its output to the serial window
char c=esp8266.read(); // read the next character.
response += c;
}
}
if (debug) {Serial.print(response);}
return response;
}
上面程式我特別將 data 變數輸出, 因為在測試 2 串列埠所擷取的訊息裡, 發現 send 出去的字串不全, 只顯示到 field2, 但實際上又有傳送到 Thingspeak, 所以用 println() 印出來看看原始字串是否有問題. 我把字串貼到 Word 去計算字元數, 剛好是 64 字元, 我想可能是軟體串列埠緩衝器設為 64 字元的關係.
在 Thingspeak 以前就有設定 field4 來顯示光度, 所以也不用修改, 程式上傳後馬上就可以看到第四欄位有資料了 :
此程式編譯後之記憶體損耗不到一半 :
草稿碼使用了 14,774 bytes (48%) 的程式存儲空間。最大值為 30,720 bytes。
全域變數使用了 920 bytes (44%) 的動態記憶體，剩餘 1,128 bytes 供局部變數。最大值為 2,048 bytes 。
好了, 此次於颱風天用 IOT 模組重做實驗到這裡就完成了. Adafruit 的函式庫沒問題的, 如果數據有問題, 可能是 DHT11 壞掉了.
上面三個程式看起來很複雜, 其實是因為我使用自製的 Arduino+ESP8266 物聯網模組之故, 為了能隨時用手機瀏覽器更改要連線的無線基地台, 程式需要 setWifi() 與 sendData() 函式來完成此功能. 參考 :
# 製作 Arduino Nano + ESP8266 物聯網模組 (三)
如果只是固定連線某個 AP 的話, 只要以 USB-TTL 線將 ESP8266 要連接的 AP 用 AT+CWJAP 指令設定好, 以後開機就會自動連上該 AP, 這樣上面的測候程式就變得很簡短 :
#include <SoftwareSerial.h>
#include "DHT.h"
#define DEBUG true
#define DHTPIN 2
#define DHTTYPE DHT11
SoftwareSerial esp8266(7,8); //(RX,TX)
DHT dht(DHTPIN, DHTTYPE); // Initialize DHT sensor
String api_key="NO5N8C7T2KINFCQE"; //Thingspeak API Write Key
void setup() {
Serial.begin(9600);
esp8266.begin(9600);
sendData("AT+RST\r\n",2000,DEBUG); // reset ESP8266
sendData("AT+GMR\r\n",1000,DEBUG);
sendData("AT+CIFSR\r\n",1000,DEBUG); //get ip address
Serial.println("DHT11 test");
dht.begin();
}
void loop() {
float h=dht.readHumidity(); //get humidity from DHT11
float c=dht.readTemperature(); //get temperature (C) from DHT11
float f=dht.readTemperature(true); //get temperature (F) from DHT11
int cds=analogRead(A0); //get cds voltage (0~5V to 0~1023 dark)
int l=100-map(cds,0,1023,0,100); //map 0~1023(dark) to 0(dark)~100%
//create data string to Thingspeak
String data="GET /update?api_key=" + api_key + "&field1=" + (String)c +
"&field2=" + (String)f + "&field3=" + (String)h + "&field4=" +
(String)l + "\r\n";
Serial.println(data);
String cmd="AT+CIPSTART=\"TCP\",\"184.106.153.149\",80\r\n";
sendData(cmd, 1000, DEBUG);
cmd="AT+CIPSEND=" + (String)data.length() + "\r\n";
sendData(cmd,1000,DEBUG);
String res=sendData(data, 2000, DEBUG);
res.replace("\r\n",""); //remove all line terminator
if (res.indexOf("Unlink") == -1) { //if no auto unlink
sendData("AT+CIPCLOSE\r\n",2000,DEBUG); //close session
}
delay(5000);
}
String sendData(String command, const int timeout, boolean debug) {
String response="";
esp8266.print(command); // send the read character to the esp8266
long int time=millis();
while ((time+timeout) > millis()) {
while(esp8266.available()) {
// The esp has data so display its output to the serial window
char c=esp8266.read(); // read the next character.
response += c;
}
}
if (debug) {Serial.print(response);}
return response;
}
編譯後記憶體損耗減少 10% 以上 :
草稿碼使用了 11,872 bytes (38%) 的程式存儲空間。最大值為 30,720 bytes。
全域變數使用了 539 bytes (26%) 的動態記憶體，剩餘 1,509 bytes 供局部變數。最大值為 2,048 bytes 。
參考 :
# Arduino教學-使用ESP8266 wifi模組+DHT 溫溼度感測器上傳thingspeak
4 則留言 :
您好,看了您的blog後,受益良多,不好意思想跟您請教一下,當網頁顯示溫濕度後,想進一步探討網頁撰寫（設定警報值,當溫度超出設定值,發出警報）,因對網頁撰寫像一張白紙,請問您有相關的書籍或其他可介紹嗎？謝謝!!
您好, 既然您對 Arduino 與網頁設計有興趣, 趙英傑的 "超圖解 Arduino 互動設計入門" 這本書裡面有對 HTML, HTTP 等網頁基本概念的圖解介紹以及與 Arduino 的搭配.
想請問一下 如果是使用mega 2560 是否就不需要在架設虛擬的TXRX接口
對, Mega 有四組 UART 埠夠用就不需要軟體的啦!
張貼留言