Athens IoT Meetup #3 - Introduction to ESP8266 (Pavlos Isaris)
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Transcript of Athens IoT Meetup #3 - Introduction to ESP8266 (Pavlos Isaris)
IntroductionThe ESP8266 WiFi Module is a self contained SOC (system on a chip) with integrated
TCP/IP protocol stack that can give any microcontroller access to a WiFi network.
Features● Very low cost ( 3-5$ )
● Pre-programmed with an AT command set firmware
● Growing community
● Enough on-board processing power to deal with sensors
through GPIO
● Operating at 3.3V
● Can draw up to 170 mA of current
● Not breadboard-friendly :-(
Why do we need a Voltage regulator?The ESP8266 may require more than the 35mA supplied by the Arduino 3.3V pin
Baud rate problemThe ESP-8266 comes in various firmware versions, varying also
in the operating baud rate (older operate at 115200 bauds).
My ESP8266 operates in 115200 bauds/second. This means that
we can only use hardware serial to communicate with it
(Arduino Software serial pins handle only 9600 bauds/second)
In such occasion, it is possible to use an Arduino MEGA (4x
Hardware serial couple-pins)
Alternative - Update firmware versionYou can also use an FTDI adapter (like the FT232rl) or FTDI
cable, to communicate via USB with ESP8266
There are plenty of tutorials about how to update the firmware
version
After you have updated the firmware version you can change the
baud rate
Module GPIO Notes
ESP-01 GPIO0/2/16 Most common module.
ESP-02 GPIO0/2/15
ESP-03 GPIO0/2/12/13/14/15/16 Most popular in esp8266.com poll
ESP-04 GPIO0/2/12/13/14/15/16
ESP-05 None
ESP-06 GPIO0/2/12/13/14/15/16
ESP-07 GPIO0/2/4/5/12/13/14/15/16
ESP-08 GPIO0/2/12/13/14/15/16
ESP-09 GPIO0/2/12/13/14/15 1MB Flash memory
ESP-10 None
ESP-11 GPIO0/1
ESP-12 ADC + GPIO0/2/4/5/12/13/14/15/16
Recently adopted by many due to many GPIOs
Using Arduino IDE Serial Monitor#include <SoftwareSerial.h>SoftwareSerial ESPserial(2, 3); // RX | TX void setup() { Serial.begin(115200); // communication with the host computer ESPserial.begin(115200); Serial.println(""); Serial.println("Remember to to set Both NL & CR in the serial monitor."); Serial.println("Ready"); Serial.println(""); }
Using Arduino IDE Serial Monitorvoid loop() { // listen for communication from the ESP8266 and then write it to the serial monitor if ( ESPserial.available() ) { Serial.write( ESPserial.read() ); } // listen for user input and send it to the ESP8266 if ( Serial.available()) { ESPserial.write( Serial.read() ); }}
Send a requestAllow multiple connections
Start connection
Specify bytes to be sent
In this case it is “GET /
HTTP/1.0\r\n\r\n”
ESP8266 core-library#include <Adafruit_ESP8266.h>
#include <SoftwareSerial.h>
#define ARD_RX_ESP_TX 2
#define ARD_TX_ESP_RX 3
#define ESP_RST 4
SoftwareSerial softser(ARD_RX_ESP_TX, ARD_TX_ESP_RX);
Adafruit_ESP8266 wifi(&softser, &Serial, ESP_RST);
#define ESP_SSID "SSIDNAME" // Your network name here
#define ESP_PASS "PASSWORD" // Your network password here
#define HOST "www.adafruit.com" // Host to contact
#define PAGE "/testwifi/index.html" // Web page to request
#define PORT 80 // 80 = HTTP default port
ESP8266 core-librarysoftser.begin(9600); // Soft serial connection to ESP8266
Serial.begin(57600); while(!Serial); // UART serial debug
wifi.connectToAP(F(ESP_SSID), F(ESP_PASS))
Serial.print(F("OK\nRequesting page..."));
if(wifi.requestURL(F(PAGE))) {
Serial.println("OK\nSearching for string...");
if(wifi.find(F("working"), true)) {
Serial.println(F("found!"));
} else {
Serial.println(F("not found."));
}
} else { // URL request failed
Serial.println(F("error"));
}
wifi.closeTCP();
Espert - Development board
http://www.espert.co/ (v2.0 To be released by April 2016.)