{"id":518,"date":"2014-09-28T17:42:33","date_gmt":"2014-09-28T15:42:33","guid":{"rendered":"http:\/\/www.verelec.nl\/?page_id=518"},"modified":"2014-09-28T18:02:42","modified_gmt":"2014-09-28T16:02:42","slug":"playing-with-the-esp8266","status":"publish","type":"page","link":"https:\/\/www.verelec.nl\/?page_id=518","title":{"rendered":"Playing with the ESP8266"},"content":{"rendered":"

\"ESP8266-WI07c-Wifi-Module-02\"<\/a>There is a new Chinese module on the market which will enable enthousiasts to build their own IoT (internet of Things) applications at relative low cost. Time to try them out. I bought 5 of them at AliExpress and received them yesterday. Today I go a simple application working (mostly borrowed code from the WEB). The code I use is:<\/p>\n

[cpp]
\n\/\/
\n\/\/ libraries
\n\/\/
\n#include "Arduino.h"
\n#include "SoftwareSerial.h"
\n#include "JsonParser.h"
\n#include <avr\/wdt.h><\/p>\n

using namespace ArduinoJson::Parser;<\/p>\n

\/\/
\n\/\/ global defines
\n\/\/
\n#define SSID "your SSID"\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/ WiFi lan at home
\n#define PASS "your SSID Password"\u00a0\u00a0 \u00a0\u00a0\u00a0 \/\/ password for WiFi lan
\n#define CONNECT_RETRIES\u00a0\u00a0 \u00a05\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/ allow 5 retries to connect to WiFi<\/p>\n

#define DST_IP "188.226.224.148" \/\/baidu.com
\n#define LOCATIONID "2925533" \/\/ location id<\/p>\n

#define DEBUG_RX\u00a0\u00a0 \u00a010\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/ pin 10 is used for receiving input from debug serial
\n#define DEBUG_TX\u00a0\u00a0 \u00a011\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/ pin 11 is used for sending output to debug serial<\/p>\n

SoftwareSerial dbgSerial(DEBUG_RX, DEBUG_TX); \u00a0\u00a0 \u00a0\/\/ used for debugging
\nJsonParser<32> parser;
\n\/\/
\n\/\/ function prototypes
\n\/\/
\nboolean connectWiFi();\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/ function to connect to WiFi
\nvoid software_Reboot();<\/p>\n

\/\/
\n\/\/ global variables
\n\/\/
\nchar cmd[100];\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/ buffer used build messages
\nchar buffer[100];
\n\/**
\n\u00a0* @name setup()
\n\u00a0* initialize the program
\n\u00a0*\/
\nvoid setup() {
\n\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\/\/ Open serial communication with WiFi module
\n\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0Serial.begin(115200);
\n\u00a0\u00a0 \u00a0Serial.setTimeout(5000);
\n\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\/\/ open debug serial
\n\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0dbgSerial.begin(9600); \u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/can’t be faster than 19200 for softserial
\n\u00a0\u00a0 \u00a0dbgSerial.println("ESP8266 Demo");\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/ show demo is starting
\n\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\/\/test if the module is ready
\n\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0bool moduleReady = false;
\n\u00a0\u00a0 \u00a0for (uint8_t i = 0; i < CONNECT_RETRIES; i++){
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0Serial.println("AT+RST");\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/ reset the module
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0delay(1000);
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0if (Serial.find("OK")) {
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/ the module is ready to receive commands
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0dbgSerial.println("Module is ready");
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0moduleReady = true;
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0break;
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0} else {
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0dbgSerial.println("Module is not responding");
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0}
\n\u00a0\u00a0 \u00a0}
\n\u00a0\u00a0 \u00a0if (!moduleReady) {
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/ module is not responding
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0dbgSerial.println("Module non functional.");
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/ reboot and try again
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0software_Reboot();
\n\u00a0\u00a0 \u00a0}
\n\/\/\u00a0\u00a0 \u00a0delay(1000);
\n\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\/\/ now connect to the wifi
\n\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0boolean connected = false;
\n\u00a0\u00a0 \u00a0for (int i = 0; i < CONNECT_RETRIES; i++) {
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/ check if we are connected
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0if (connectWiFi()) {
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/ we have a connection
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0connected = true;
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/ done
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0break;
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0}
\n\u00a0\u00a0 \u00a0}
\n\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\/\/ if we cannot connect no use continuing
\n\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0if (!connected) {
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/ inform user
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0dbgSerial.println("Cannot connect to WiFi lan");
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0while (1) {};
\n\u00a0\u00a0 \u00a0}<\/p>\n

\u00a0\u00a0 \u00a0delay(5000);
\n\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\/\/ show the IP address we have received
\n\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0Serial.println("AT+CIFSR");
\n\u00a0\u00a0 \u00a0delay(3000);
\n\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\/\/ wait for incoming message with IP address
\n\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0while (!Serial.available()){};
\n\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\/\/ copy the message to output
\n\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0uint16_t bufferIndex = 0;
\n\u00a0\u00a0 \u00a0while (Serial.available()) {
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0char x = Serial.read();
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/ ignore any CR’s, LF’s and zero characters
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0if (x != 0x0D && x != 0x0A && x != 0x0) {
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/ add character to buffer
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0buffer[bufferIndex] = x;
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0bufferIndex++;
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0}
\n\u00a0\u00a0 \u00a0}
\n\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\/\/ put in a string terminator
\n\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0buffer[bufferIndex] = ‘\0’;
\n\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\/\/ and display the IP address
\n\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0dbgSerial.print("ip address: ");
\n\u00a0\u00a0 \u00a0dbgSerial.println(&buffer[8]);
\n\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0\/\/ set the single connection mode
\n\u00a0\u00a0 \u00a0\/\/
\n\u00a0\u00a0 \u00a0Serial.println("AT+CIPMUX=0");
\n}
\nvoid loop() {
\n\u00a0\u00a0 \u00a0String cmd = "AT+CIPSTART=\\"TCP\\",\\"";
\n\u00a0\u00a0 \u00a0\u00a0 cmd += DST_IP;
\n\u00a0\u00a0 \u00a0\u00a0 cmd += "\\",80";
\n\u00a0\u00a0 \u00a0\u00a0 Serial.println(cmd);
\n\u00a0\u00a0 \u00a0\u00a0 dbgSerial.println(cmd);
\n\u00a0\u00a0 \u00a0\u00a0 if(Serial.find("Error")) return;
\n\u00a0\u00a0 \u00a0\u00a0 cmd = "GET \/data\/2.5\/weather?id=";
\n\u00a0\u00a0 \u00a0\u00a0 cmd += LOCATIONID;
\n\u00a0\u00a0 \u00a0\u00a0 cmd += " HTTP\/1.0\\r\\nHost: api.openweathermap.org\\r\\n\\r\\n";
\n\u00a0\u00a0 \u00a0\u00a0 Serial.print("AT+CIPSEND=");
\n\u00a0\u00a0 \u00a0\u00a0 Serial.println(cmd.length());
\n\u00a0\u00a0 \u00a0\u00a0 if(Serial.find(">")){
\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 dbgSerial.print(">");
\n\u00a0\u00a0 \u00a0\u00a0 }else{
\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 Serial.println("AT+CIPCLOSE");
\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 dbgSerial.println("connection timeout");
\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 delay(1000);
\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 return;
\n\u00a0\u00a0 \u00a0\u00a0 }
\n\u00a0\u00a0 \u00a0\u00a0 Serial.print(cmd);
\n\u00a0\u00a0 \u00a0\u00a0 unsigned int i = 0; \/\/timeout counter
\n\u00a0\u00a0 \u00a0\u00a0 int n = 1; \/\/ char counter
\n\u00a0\u00a0 \u00a0\u00a0 char json[100]="{";
\n\u00a0\u00a0 \u00a0\u00a0 while (!Serial.find("\\"main\\":{")){} \/\/ find the part we are interested in.
\n\u00a0\u00a0 \u00a0\u00a0 while (i<60000) {
\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 if(Serial.available()) {
\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 char c = Serial.read();
\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 json[n]=c;
\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 if(c==’}’) break;
\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 n++;
\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 i=0;
\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 }
\n\u00a0\u00a0 \u00a0\u00a0\u00a0\u00a0 i++;
\n\u00a0\u00a0 \u00a0\u00a0 }
\n\u00a0\u00a0 \u00a0\u00a0 dbgSerial.println(json);
\n\u00a0\u00a0 \u00a0\u00a0 JsonObject root = parser.parse(json);
\n\u00a0\u00a0 \u00a0\u00a0 double temp = root["temp"];
\n\u00a0\u00a0 \u00a0\u00a0 double pressure = root["pressure"];
\n\u00a0\u00a0 \u00a0\u00a0 double humidity = root["humidity"];
\n\u00a0\u00a0 \u00a0\u00a0 temp -= 273.15; \/\/ from kelvin to degree celsius
\n\u00a0\u00a0 \u00a0\u00a0 dbgSerial.println(temp);
\n\u00a0\u00a0 \u00a0\u00a0 dbgSerial.println(pressure);
\n\u00a0\u00a0 \u00a0\u00a0 dbgSerial.println(humidity);
\n\u00a0\u00a0 \u00a0\u00a0 dbgSerial.println("====");
\n\u00a0\u00a0 \u00a0\u00a0 delay(30000);
\n}
\nboolean connectWiFi() {
\n\u00a0\u00a0 \u00a0Serial.println("AT+CWMODE=1");
\n\u00a0\u00a0 \u00a0strcpy(cmd,"AT+CWJAP=\\"");
\n\u00a0\u00a0 \u00a0strcat(cmd,SSID);
\n\u00a0\u00a0 \u00a0strcat(cmd, "\\",\\"");
\n\u00a0\u00a0 \u00a0strcat(cmd, PASS);
\n\u00a0\u00a0 \u00a0strcat(cmd, "\\"");
\n\u00a0\u00a0 \u00a0dbgSerial.println(cmd);
\n\u00a0\u00a0 \u00a0Serial.println(cmd);
\n\u00a0\u00a0 \u00a0delay(2000);
\n\u00a0\u00a0 \u00a0if (Serial.find("OK")) {
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0dbgSerial.println("OK, Connected to WiFi.");
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0return true;
\n\u00a0\u00a0 \u00a0} else {
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0dbgSerial.println("Can not connect to the WiFi.");
\n\u00a0\u00a0 \u00a0\u00a0\u00a0 \u00a0return false;
\n\u00a0\u00a0 \u00a0}
\n}
\nvoid software_Reboot()
\n{
\n\u00a0 wdt_enable(WDTO_15MS);
\n\u00a0 while(1)
\n\u00a0 {
\n\u00a0 }
\n}<\/p>\n

[\/cpp]<\/p>\n

But most important…. It works :).\u00a0 I used a simple DC-DC switcher to convert from 5V -> 3.3V. No level shifters… Sofar the chip still works and does not get hot or anything.\u00a0 Pretty straight forward. Next steps:<\/p>\n