ESP8266 Thing Developpment Board w/ Headers Introduction

1/23/2018 ESP8266 Thing Development Board Hookup Guide - learn.sparkfun.com
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There’s only one analog input pin, labeled ADC. To read the ADC pin, make a function call to analogRead(A0) . Remember that this
pin has a weird maximum voltage of 1V – you’ll get a 10-bit value (0-1023) proportional to a voltage between 0 and 1V.
All digital pins are also capable of PWM “analog” output. Use analogWrite([pin], [value]) with a value between 0 and 1023 to
dim LEDs with a 1kHz PWM signal.
Yielding
This is one of the most critical differences between the ESP8266 and a classic Arduino microcontroller. The ESP8266 runs a lot of
utility functions in the background – keeping WiFi connected, managing the TCP/IP stack, and performing other duties – blocking
these functions from running can cause the ESP8266 to crash and reset itself. To avoid these mysterious resets, avoid long,
blocking loops in your sketch.
If you have a long loop in your sketch, you can add a delay([milliseconds]) call within, to allow the critical background functions
to execute. The ESP8266’s delay() funciton, while of course delaying for a set number of milliseconds, also makes a quick call to
the background functions.
The ESP8266 Arduino libraries also implement a yield() function, which calls on the background functions to allow them to do
their thing. As an example, if your sketch is waiting for someone to press a button attached to pin 12, creating a loop like this will
keep the ESP8266 from crashing:
pinMode(12, INPUT_PULLUP); // Set pin 12 as an input w/ pull-up
while (digitalRead(12) == HIGH) // While pin 12 is HIGH (not activated)
yield(); // Do (almost) nothing -- yield to allow ESP8266 background functions
Serial.println("Button is pressed!"); // Print button pressed message.
ESP8266WiFi Class
This is the ESP8266, so the WiFi class will probably be included in just about every sketch there is. If you’ve used the Arduino WiFi
library before, the ESP8266 WiFi library will be very similar, there’s just a few key differences:
To include the ESP8266 WiFi library call #include <ESP8266WiFi.h> not <WiFi.h> .
To connect to a network, like the normal WiFi library, call WiFi.begin(NetworkSSID, NetworkPassword) . You can also set the
ESP8266 up as a WiFi access point by calling WiFi.softAP(AP_SSID, AP_Password) .
To set the ESP8266’s mode, which can be access point (AP), station (STA), or combo (the ESP8266 can do both at the same
time!), call WiFi.setMode([mode]) with either WIFI_AP , WIFI_STA , or WIFI_STA_AP as the parameter.
The examples earlier in this tutorial should have demonstrated all of these differences.
Libraries Available/Not Available and the Differences