WRL-13231 - SparkFun Electronics

ESP8266 Thing Hookup Guide

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Introduction

Over the past year, the ESP8266 has been a growing star among IoT or

WiFi-related projects. It’s an extremely cost-effective WiFi module, that –

with a little extra effort – can be programmed just like any microcontroller.

Unfortunately, the ESP8266 has mostly only been available in a tiny,

modular form, which, with limited I/O and a funky pin-out, can be difficult to

build a project around.

The original ESP8266 WiFi module. Great for piggybacking onto an

Arduino, hard to build a project around.

SparkFun’s new development board for the ESP8266 breaks out all of the

module’s pins, and comes equipped with a LiPo charger, power supply, and

all of the other supporting circuitry it requires. We lovingly call it the Thing –

it’s the perfect foundation for your Internet of Things.

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ESP8266 Thing Hookup Guide SparkFun Wish List

Covered in this Tutorial

This tutorial will familiarize you with all things SparkFun Thing. It’s split into

sections, which cover:

• Hardware Overview – A quick rundown of the Thing’s components

and pinout.

• Powering the Thing – The Thing can be powered through either USB

or a LiPo battery.

• Programming the Thing – Interface a 3.3V FTDI Basic with the Thing

to program it.

• Hardware Assembly – Tips and recommendations on what to solder

to the Thing’s I/O pins.

• Installing the ESP8266 Arduino Addon – The Thing can be

programmed using Arduino! Just follow the instructions here to install

the board definitions.

• Example Sketch: Posting to Phant – Our first example shows how

you can use the Thing to post data to data.sparkfun.com.

• Example Sketch: AP Web Server – Set the Thing up as an access

point and use it to serve web pages.

• Example Sketch: Goodnight Thing (Sleep Mode) – Put the Thing to

sleep to save that sweet battery juice.

• Using the Arduino Addon – There are a few key differences between

programming the Thing and any other Arduino board.

Required Materials

To follow along with this tutorial, and get up-and-running with the Thing, you

may need a few extra tools and materials. This wishlist includes everything

we use in this tutorial to program and use the Thing:

SparkFun ESP8266 Thing

WRL-13231

The SparkFun ESP8266 Thing is essentially a breakout and develop…

SparkFun Cerberus USB Cable - 6ft

CAB-12016

You've got the wrong USB cable. It doesn't matter which one you hav…

SparkFun FTDI Basic Breakout - 3.3V

DEV-09873

This is the newest revision of our [FTDI Basic](http://www.sparkfun.co…

(2) Arduino Stackable Header - 10 Pin

PRT-11376

This is a 10-pin female header, with extra long legs -- great for stackin…

Polymer Lithium Ion Battery - 850mAh

Page 2 of 2

PRT-00341

These are very slim, extremely light weight batteries based on the ne…

Suggested Reading

Before continuing on with this tutorial, you may want to familiarize yourself

with some of these topics if they’re unfamiliar to you:

• How to Power a Project

• Logic Levels

• Serial Communication

• How to Solder

Hardware Overview

The ESP8266 Thing is a relatively simple board. The pins are broken out to

two parallel, breadboard-compatible rows. USB and LiPo connectors at the

top of the board provide power – controlled by the nearby ON/OFF switch.

And LEDs towards the inside of the board indicate power, charge, and

status of the IC.

Here’s a quick overview of the Thing’s main components:

The Pinout

The Thing’s I/O headers can be broken down into three sections:

Serial Programming Header

This six-pin header will be the main point of contact between the Thing and

your development computer. The pinout of this header matches the

extremely common “FTDI header.” That means you can interface it with

either a 3.3V FTDI Basic or a 3.3V I/O FTDI Cable to program and debug

the Thing.

For a quick breakdown of the pins on this header, consult the table below. If

a pin is directly tied to an ESP8266 I/O, it’ll be noted:

Label

ESP8266

I/O #

Notes

DTR Performs auto-reset, and puts the ESP8266 into

bootloader mode. Connects through a capacitor

to RESET, and a buffer to the ESP8266's

GPIO0.

TXO 7 ESP8266 UART1 data output.

RXI 8 ESP8266 UART1 data input.

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3V3 By default, this pin does not supply the ESP8266

directly (a jumper on the back can change that).

NC Not connected to anything on the Thing.

GND Ground (0V).

IC Header

I C is a very popular communication protocol in the embedded world.

Whether you want to hook the Thing up to a motion sensor, light sensor,

digital-to-analog converter, or OLED display, I C is often the protocol of

choice.

This header includes four pins – all that should be required to connect an

I C device up to the Thing.

Label

ESP8266

I/O #

Notes

GND Ground (0V).

3V3 3.3V

SDA 2 Can either be used as ESP8266 GPIO2 or

I C serial data (SDA).

SCL 14 Can either be used as ESP8266 GPIO14 or

I C serial clock (SCL).

Also used as the SPI clock (SCLK).

This pinout matches that of most of our I C-based breakout boards, so you

can piggyback them right on top of the Thing.

If you need the extra I/O, instead of I C, the SDA and SCL pins can be used

as GPIO 2 and 14 respectively. The SCL pin also serves as the clock

(SCLK) for the ESP8266’s SPI interface.

General I/O Header

The rest of the power, control, and I/O pins are broken out on the other side

of the board. They are:

Label

ESP8266

I/O #

Notes

GND Ground (0V).

VIN USB connected: ~4.5V output

LiPo connected (no USB): ~3.7V output

No supply: Can be used as a voltage supply

input to the 3.3V regulator.

55 This pin is also tied to the on-board LED.

13 13 Hardware SPI MOSI

12 12 Hardware SPI MISO

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XPD 16 Can be connected to reset to set the

ESP8266 into deep sleep mode.

ADC A0 A 10-bit ADC with a maximum voltage of 1V.

EN ESP8266 enable pin. HIGH = on, LOW = off.

Pulled HIGH on-board.

What happened to the rest of the GPIO pins? Why the eclectic pin-

numbering scheme? We’re taking what the ESP8266 gives us.

Unfortunately, most of the remaining GPIO are connected to the on-board

SPI flash memory IC, which stores the ESP8266’s program memory and

potentially other data.

Back of the Thing

Flipping the Thing over revels a few trace jumpers and test points, which

you may find handy for your application. (Plus a friendly Phant.io logo, to

remind you about our data storage service on data.sparkfun.com.)

Jumpers

Jumper

Label

Default

Setting

Notes

DTR Closed Allows for auto-reset while programming the

ESP8266, but makes serial debugging

difficult.

I2C PU Closed Connects 10kΩ pull-up resistors to the SDA

and SCL pins.

FTDI VCC Open Connects the 3V3 pin on the serial header

directly to the ESP8266's 3.3V supply.

Of these jumpers, the DTR one is the most commonly modified. The DTR

output of the FTDI Basic is used for two purposes: to reset the ESP8266

and pull GPIO0 low (putting the chip in bootloader mode). Keeping this

jumper closed enables programming, but makes debugging via the Serial

Monitor difficult, as the board will reset into bootloader mode whenever the

terminal opens. Using and modifying this jumper is discussed later in this

tutorial.

The FTDI_VCC jumper defaults to open to ensure that, if a 3.3V Logic (5V

power) FTDI Cable is used to program the Thing, 5V isn’t accidentally

delivered to the IC. Also, most 3.3V FTDI boards don’t have a lot of juice to

supply on the 3.3V bus (they often supply about 50mA max).

Test Points

These pins are made available just in case they become necessary to your

project. The six pins bundled up together are connected to the Thing’s on-

board SPI flash memory, but if you really need the extra GPIO, or want to

experiment with the pins, they’re available.

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The RST pin is more useful, but we didn’t leave room to break it out – at

least not directly. RST is tied through a 0.1µF capacitor to the DTR pin, to

allow for automatic reset during programming. For many applications that

need the RST pin, toggling the DTR pin works as well. Putting the ESP8266

into deep sleep is one such application.

Selecting the Antenna

The Thing’s default WiFi antenna is a PCB trace antenna based on this TI

app note. It’s cost-effective and actually works really well!

If you need to connect a more sensitive antenna to the chip, a U.FL

connector is also available on the board, but isn’t connected by default to

the ESP8266’s antenna pin. To connect this antenna to the chip, you’ll

need to heat up the 0Ω resistor and rotate it 90°:

An (ugly, uncleaned) resistor swapped from printed antenna to U.FL

antenna.

A soldering iron, pair of tweezers, (2) steady hands, and good set of eyes

should be enough to accomplish the task.

Why Are There Unpopulated Parts?

We initially set out to make the Thing a secure, common-sensor base

station. The empty pads you see are landing spots for three unique IC’s:

• ATECC108A – A “full turnkey Elliptic Curve Digital Signature

Algorithm (ECDSA) engine”, which can be used for unique serial

numbers, hashing, key storage, or random numbers. A great start to

securing your IoT project!

• TMP102 Temperature Sensor – A simple, 12-bit, digital temperature

sensor.

• TSL2561 Light Sensor – A nifty luminosity/light sensor.

• Plus a few footprints for decoupling capacitors.

After a late change of heart, we decided to keep the board as low cost as

possible (that’s the ESP8266’s best feature!), while leaving the option for

later expansion. The pads are still there. If you want to add any of these

components, hopefully all you should need is a hot air station (maybe

probably not a Heaterizer) and some tweezers.

Powering the Thing

The Thing provides for two methods of power delivery: USB or LiPo. The

USB connector on the Thing is of the Micro-B variety. A micro-B cable

plugged into either a computer USB port or a 5V USB Wall Wart can power

the Thing.

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Any of our single-cell LiPo batteries will also work to power the Thing – they

all have the same 2-pin JST connector.

Add an 850mAh LiPo and an LSM9DS0 9DoF IMU to the Thing, to create

an IoT motion sensor.

If both USB and LiPo are connected to the Thing, it’ll take power from the

USB port and charge the LiPo battery at up to 500mA.

Electrical Characteristics

The ESP8266’s maximum voltage is 3.6V, so the Thing has an onboard

3.3V regulator to deliver a safe, consistent voltage to the IC. That means

the ESP8266’s I/O pins also run at 3.3V, you’ll need to level shift any 5V

signals running into the IC.

The input to this regulator can either be delivered by USB, LiPo battery, or

through the VIN pin.

Max Input Voltage: If you supply power to the board through the VIN,

make sure the voltage does not exceed 6V. That's the maximum input

voltage of the AP2112K-3.3V regulator the board uses.

Alternatively, if you have an external, regulated, supply you’d like to deliver

directly to the ESP8266, you can supply that voltage through the 3V3 pin

(on the I C header). While this voltage doesn’t have to be 3.3V, it must be

within the range of 1.7-3.6V.

Current Ratings

On average, the Thing pulls about 80mA. WiFi transmits and receives can

momentarily increase that draw. Here’s a table, transcribed from the

ESP8266 datasheet, with some of the more common current

characteristics.

Parameter Typical Max Unit

Transmit 802.11b (1 Mbps) 215 mA

Transmit 802.11b (11 Mbps) 197 mA

Transmit 802.11g (54 Mbps) 145 mA

Transmit 802.11n 135 mA

Receive 802.11b 60 mA

Receive 802.11g 60 mA

Receive 802.11n 62 mA

Standby 0.9 mA

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Deep Sleep 10 µA

Maximum I/O Pin Drive Capability 12 mA

If your application requires maximum battery life, you’ll likely need to make

liberal use of the ESP8266’s deep sleep functionality. That’ll be covered

later in this tutorial.

Programming the Thing

The ESP8266 has a built-in serial bootloader, which allows for easy

programming and re-programming. You don’t need a specialized,

expensive programmer – just a simple, USB-to-Serial converter.

We use a 3.3V FTDI Basic to program the Thing, but other serial converters

with 3.3V I/O levels should work (e.g. FTDI SmartBasic, FTDI Cable 5V

VCC-3.3V I/O, FT231X Breakout. The converter does need a DTR line in

addition to the RX and TX pins.

The FTDI Basic’s 6-pin header matches up exactly to the Thing’s 6-pin

serial port header. To set up for programming, simply connect the FTDI

directly to this port – take care to match up the DTR and GND pins!

If you’re short on USB ports, the SparkFun Cerberus Cable might be just

what you need.

If you solder female headers to the Thing, plugging a 6-pin row of right-

angle male headers between the FTDI and header helps create a

temporary programming interface.

Hardware Assembly

Oh. We’re getting ahead of ourselves. To connect the FTDI programmer to

your Thing you’ll need to solder something to the Thing.

If you’ve never soldered before, this is a great time to start! These solder

points are easy, through-hole pins, check out our How to Solder - Through-

hole Soldering for help getting started.

What, exactly, you solder to the board depends both on how you’ll use it in

your project, and how you’ll interface it with the programmer. When it

comes to selecting a header (or wire) to solder, there are a variety of

options. We’ve tried a lot of them with the Thing:

10-pin Stackable Headers make it convenient to both breadboard the Thing

and jumper wire out of it.

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Or you can mix and match headers to best fit your needs. Right-angle male

headers may help to interface between the FTDI and the Thing. Straight

male headers are a good choice for low-profile connections. Straight female

headers may help with connecting to I C sensors. And, of course, wire can

be soldered to any of the pins that have a long way to connect to

something.

Once you’ve soldered up at least the programming port, you’re ready to

load some code onto the Thing. Let’s blink some LEDs and IoT (Internet

our Thing).

Installing the ESP8266 Arduino Addon

There are a variety of development environments that can be equipped to

program the ESP8266. You can go with a simple Notepad/gcc setup, or

fine-tune an Eclipse environment, use a virtual machine provided by

Espressif, or come up with something of your own.

Fortunately, the amazing ESP8266 community recently took the IDE

selection a step further by creating an Arduino addon. If you’re just getting

started programming the ESP8266, this is the environment we recommend

beginning with, and the one we’ll document in this tutorial.

This ESP8266 addon for Arduino is based on the amazing work by Ivan

Grokhotkov and the rest of the ESP8266 community. Check out the

ESP8266 Arduino GitHub repository for more information.

Installing the Addon With the Arduino Boards

Manager

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With the release of Arduino 1.6.4, adding third party boards to the Arduino

IDE is easily achieved through the new board manager. If you’re running an

older version of Arduino (1.6.3 or earlier), we recommend upgrading now.

As always, you can download the latest version of Arduino from arduino.cc.

To begin, we’ll need to update the board manager with a custom URL.

Open up Arduino, then go to the Preferences (File > Preferences). Then,

towards the bottom of the window, copy this URL into the “Additional Board

Manager URLs” text box:

https://raw.githubusercontent.com/sparkfun/Arduino_Boards/esp8

266/IDE_Board_Manager/package_sparkfun_index.json

If you already have a URL in there, and want to keep it, you can separate

multiple URLs by placing a comma between them.

Hit OK. Then navigate to the Board Manager by going to Tools > Boards >

Boards Manager. There should be a couple new entries in addition to the

standard Arduino boards. Look for SparkFun ESP8266 Boards. Click on

that entry, then select Install.

The board definitions and tools for the ESP8266 Thing include a whole new

set of gcc, g++, and other reasonably large, compiled binaries, so it may

take a few minutes to download and install (the archived file is ~110MB).

Once the installation has completed, an Arduino-blue “INSTALLED” will

appear next to the entry.

Selecting the ESP8266 Thing Board

With the Board addon installed, all that’s left to do is select “ESP8266

Thing” from the Tools > Boards menu.

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Then select your FTDI’s port number under the Tools > Port menu.

Upload Blink

To verify that everything works, try uploading the old standard: Blink.

Instead of blinking pin 13, like you may be used to though, toggle pin 5,

which is attached to the onboard LED.

#defineESP8266_LED5

void setup()

{

pinMode(ESP8266_LED,OUTPUT);

}

void loop()

{

digitalWrite(ESP8266_LED,HIGH);

delay(500);

digitalWrite(ESP8266_LED,LOW);

delay(500);

}

If the upload fails, first make sure the ESP8266 Thing is turned on – the red

“PWR” LED should be illuminated.

There are still some bugs to be fleshed out of the esptool, sometimes it may

take a couple tries to successfully upload a sketch. If you continue to fail,

try turning the ESP8266 Thing on then off, or unplug then replug the FTDI

in. If you still have trouble, get in touch with our amazing tech support team.

Example Sketch: Posting to Phant

Our main goal for creating the ESP8266 Thing was finding a good platform

to interact with our free online data storage service: data.sparkfun.com.

Here’s a simple example sketch that posts four values to a test stream.

Feel free to use that stream temporarily to make sure your Thing is working

(don’t abuse it please!).

Copy the code below, or download the example sketch.

Before uploading your code to the Thing, make sure you modify the

WiFiSSD and WiFiPSK variables, setting them to the SSID and password

of your WiFi network. The rest of the sketch should just work.

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//IncludetheESP8266WiFilibrary.(Worksalotlikethe

//ArduinoWiFilibrary.)

#include<ESP8266WiFi.h>

//IncludetheSparkFunPhantlibrary.

#include<Phant.h>

//////////////////////

//WiFiDefinitions//

//////////////////////

const char WiFiSSID[]= "WiFi_Network";

const char WiFiPSK[]= "WiFi_Password";

/////////////////////

//PinDefinitions//

/////////////////////

const int LED_PIN=5;//Thing'sonboard,greenLED

const int ANALOG_PIN= A0;//TheonlyanalogpinontheThing

const int DIGITAL_PIN= 12;//Digitalpintoberead

////////////////

//PhantKeys//

////////////////

const char PhantHost[]= "data.sparkfun.com";

const char PublicKey[]= "wpvZ9pE1qbFJAjaGd3bn";

const char PrivateKey[]= "wzeB1z0xWNt1YJX27xdg";

/////////////////

//PostTiming//

/////////////////

const unsigned long postRate= 30000;

unsigned long lastPost=0;

void setup()

{

initHardware();

connectWiFi();

digitalWrite(LED_PIN,HIGH);

}

void loop()

{

if (lastPost+ postRate<= millis())

{

if (postToPhant())

lastPost= millis();

else

delay(100);

}

}

void connectWiFi()

{

byteledStatus= LOW;

//SetWiFimodetostation(asopposedtoAPorAP_STA)

WiFi.mode(WIFI_STA);

//WiFI.begin([ssid],[passkey])initiatesaWiFIconnection

//tothestated[ssid],usingthe[passkey]asaWPA,WPA2,

//orWEPpassphrase.

WiFi.begin(WiFiSSID,WiFiPSK);

//UsetheWiFi.status()functiontocheckiftheESP8266

//isconnectedtoaWiFinetwork.

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while (WiFi.status()!= WL_CONNECTED)

{

//BlinktheLED

digitalWrite(LED_PIN,ledStatus);//WriteLEDhigh/low

ledStatus= (ledStatus== HIGH)?LOW:HIGH;

//DelaysallowtheESP8266toperformcriticaltasks

//definedoutsideofthesketch.Thesetasksinclude

//settingup,andmaintaining,aWiFiconnection.

delay(100);

//Potentiallyinfiniteloopsaregenerallydangerous.

//Adddelays allowingtheprocessortoperformother

//tasks whereverpossible.

}

}

void initHardware()

{

Serial.begin(9600);

pinMode(DIGITAL_PIN,INPUT_PULLUP);

pinMode(LED_PIN,OUTPUT);

digitalWrite(LED_PIN,LOW);

//Don'tneedtosetANALOG_PINasinput,

//that'sallitcanbe.

}

int postToPhant()

{

//LEDturnsonwhenweenter,it'llgooffwhenwe

//successfullypost.

digitalWrite(LED_PIN,HIGH);

//DeclareanobjectfromthePhantlibrary phant

Phantphant(PhantHost,PublicKey,PrivateKey);

//Doalittleworktogetauniqueishname.Appendthe

//lasttwobytesoftheMAC(HEX'd)to"Thing":

uint8_tmac[WL_MAC_ADDR_LENGTH];

WiFi.macAddress(mac);

String macID= String(mac[WL_MAC_ADDR_LENGTH 2],HEX)+

String(mac[WL_MAC_ADDR_LENGTH 1],HEX);

macID.toUpperCase();

String postedID= "Thing" + macID;

//Addthefourfield/valuepairsdefinedbyourstream:

phant.add("id",postedID);

phant.add("analog",analogRead(ANALOG_PIN));

phant.add("digital",digitalRead(DIGITAL_PIN));

phant.add("time",millis());

//Nowconnecttodata.sparkfun.com,andpostourdata:

WiFiClientclient;

const int httpPort= 80;

if (!client.connect(PhantHost,httpPort))

{

//Ifwefailtoconnect,return0.

return 0;

}

//Ifwesuccessfullyconnected,printourPhantpost:

client.print(phant.post());

//Readallthelinesofthereplyfromserverandprintthe

mtoSerial

while(client.available()){

String line= client.readStringUntil('\r');

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//Serial.print(line);//Tryingtoavoidusingserial

}

//Beforeweexit,turntheLEDoff.

digitalWrite(LED_PIN,LOW);

return 1;//Returnsuccess

}

After loading the code onto your Thing, it will begin to run. The status LED

connected to pin 5 will initially blink at about 2 Hz. After the Thing connects

to your network, the green LED will turn solid and post to the test stream. At

that point the LED will go dark, only blinking every 30s-or-so as the Thing

posts to Phant again.

If the LED never stops blinking, your Thing is probably having trouble

connecting to the WiFi network. Make sure the SSID and PSK variables are

set correctly.

Four values are posted to the Phant stream: the reading from the ADC pin,

a digital reading from pin 12, the Thing’s ID (“Thing” appendd with the last

two MAC bytes), and a time variable loaded from the millis() function.

Load up the test stream to check for your Thing’s signature there!

Example screenshot from our communal data.sparkfun.com stream.

Read through the comments in the code to get a line-by-line breakdown of

what’s going on in the sketch.

Example Sketch: AP Web Server

Not only can the ESP8266 connect to a WiFi network and interact with the

Internet, but it can also set up a network of its own, allowing other devices

to connect directly to it. This example demonstrates how to turn the

ESP8266 into an access point (AP), and serve up web pages to any

connected client.

Copy and paste the code from below, or download it here.

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#include<ESP8266WiFi.h>

//////////////////////

//WiFiDefinitions//

//////////////////////

const char WiFiAPPSK[]= "sparkfun";

/////////////////////

//PinDefinitions//

/////////////////////

const int LED_PIN=5;//Thing'sonboard,greenLED

const int ANALOG_PIN= A0;//TheonlyanalogpinontheThing

const int DIGITAL_PIN= 12;//Digitalpintoberead

WiFiServerserver(80);

void setup()

{

initHardware();

setupWiFi();

server.begin();

}

void loop()

{

//Checkifaclienthasconnected

WiFiClientclient=server.available();

if (!client){

return;

}

//Readthefirstlineoftherequest

String req= client.readStringUntil('\r');

Serial.println(req);

client.flush();

//Matchtherequest

int val=1;//We'lluse'val'tokeeptrackofboththe

//requesttype(read/set)andvalueifset.

if (req.indexOf("/led/0")!= 1)

val=0;//WillwriteLEDlow

else if (req.indexOf("/led/1")!= 1)

val=1

;//WillwriteLEDhigh

else if (req.indexOf("/read")!= 1)

val=2;//Willprintpinreads

//Otherwiserequestwillbeinvalid.We'llsayasmuchinH

TML

//SetGPIO5accordingtotherequest

if (val>= 0)

digitalWrite(LED_PIN,val);

client.flush();

//Preparetheresponse.Startwiththecommonheader:

String s= "HTTP/1.1200OK\r\n";

s+= "ContentType:text/html\r\n\r\n";

s+= "<!DOCTYPEHTML>\r\n<html>\r\n";

//Ifwe'resettingtheLED,printoutamessagesayingwed

if (val>= 0)

{

s+= "LEDisnow";

s+= (val)?"on":"off";

Page 1

of 2

}

else if (val== 2)

{//Ifwe'rereadingpins,printoutthosevalues:

s+= "AnalogPin=";

s+= String(analogRead(ANALOG_PIN));

s+= "<br>";//Gotothenextline.

s+= "DigitalPin12=";

s+= String(digitalRead(DIGITAL_PIN));

}

else

{

s+= "InvalidRequest.<br>Try/led/1,/led/0,or/read.";

}

s+= "</html>\n";

//Sendtheresponsetotheclient

client.print(s);

delay(1);

Serial.println("Clientdisonnected");

//Theclientwillactuallybedisconnected

//whenthefunctionreturnsand'client'objectisdetroyed

}

void setupWiFi()

{

WiFi.mode(WIFI_AP);

//Doalittleworktogetauniqueishname.Appendthe

//lasttwobytesoftheMAC(HEX'd)to"Thing":

uint8_tmac[WL_MAC_ADDR_LENGTH];

WiFi.softAPmacAddress(mac);

String macID= String(mac[WL_MAC_ADDR_LENGTH 2],HEX)+

String(mac[WL_MAC_ADDR_LENGTH 1],HEX);

macID.toUpperCase();

String AP_NameString= "ESP8266Thing" + macID;

char AP_NameChar[AP_NameString.length()+ 1];

memset(AP_NameChar,AP_NameString.length()+1,0);

for (int i=0;i<AP_NameString.length();i++)

AP_NameChar[i]= AP_NameString.charAt(i);

WiFi.softAP(AP_NameChar,WiFiAPPSK);

}

void initHardware()

{

Serial.begin(115200);

pinMode(DIGITAL_PIN,INPUT_PULLUP);

pinMode(LED_PIN,OUTPUT);

digitalWrite(LED_PIN,LOW);

//Don'tneedtosetANALOG_PINasinput,

//that'sallitcanbe.

}

After uploading this sketch, find another device that you can connect to a

WiFi network – phone, laptop, etc. Look for a network called “Thing-XXXX”,

where XXXX is the last 2 bytes of the Thing’s MAC address.

Page 1

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The sketch sets the network’s password to “sparkfun”.

After connecting to your Thing’s AP network, load up a browser and point it

to 192.168.4.1/read . The Thing should serve up a web page showing you

its ADC and digital pin 12 readings:

After that, give 192.168.4.1/led/0 and 192.168.4.1/led/1 a try, and

keep an eye on the Thing’s green LED while you do.

As always, check through the code comments to get a line-by-line

breakdown of what’s going on.

Example Sketch: Goodnight Thing

(Sleep Mode)

One of the Thing’s most unique features is the integrated support for LiPo

batteries. Unfortunately, the ESP8266 is still a pretty power hungry device.

If you want your project to run off a battery for more than a few hours, you

have two options: get a huge battery or cleverly put the Thing to sleep.

To use the Thing’s sleep capability, you’ll need to wire the XPD pin up to

the ESP8266’s reset line. RST isn’t broken out, but the DTR pin will work

for our application as well.

Wire up from the XPD pin to DTR to set up sleep-ability.

Watch out! The ESP8266 can't be programmed while the XPD pin is

connected to DTR. Make sure you disconnect the two pins before

trying to upload a sketch.

Page 1

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After you tell the ESP8266 to sleep, it’ll wait a specified number of

microseconds, then trigger the XPD pin to toggle the reset line. When the

ESP8266 wakes up, it’ll begin back at the start of the sketch.

Let’s riff off the first example in this tutorial – posting to Phant – but take

advantage of sleeping to greatly increase the battery life. Here’s some

example code (or click here to download):

Once again, make sure you modify the WiFiSSID and WiFiPSK variables

near the top of the sketch.

Page 18 of 2

//IncludetheESP8266WiFilibrary.(Worksalotlikethe

//ArduinoWiFilibrary.)

#include<ESP8266WiFi.h>

//IncludetheSparkFunPhantlibrary.

#include<Phant.h>

//////////////////////

//WiFiDefinitions//

//////////////////////

const char WiFiSSID[]= "WiFi_Network";

const char WiFiPSK[]= "WiFi_Password";

/////////////////////

//PinDefinitions//

/////////////////////

const int LED_PIN=5;//Thing'sonboard,greenLED

const int ANALOG_PIN= A0;//TheonlyanalogpinontheThing

const int DIGITAL_PIN= 12;//Digitalpintoberead

////////////////

//PhantKeys//

////////////////

const char PhantHost[]= "data.sparkfun.com";

const char PublicKey[]= "wpvZ9pE1qbFJAjaGd3bn";

const char PrivateKey[]= "wzeB1z0xWNt1YJX27xdg";

//Timetosleep(inseconds):

const int sleepTimeS= 30;

void setup()

{

initHardware();

connectWiFi();

digitalWrite(LED_PIN,HIGH);

while (postToPhant()!= 1)

{

delay(100);

}

digitalWrite(LED_PIN,LOW);

//deepSleeptimeisdefinedinmicroseconds.Multiply

//secondsby1e6

ESP.deepSleep(sleepTimeS* 1000000);

}

void loop()

{

}

void connectWiFi()

{

byteledStatus=LOW;

//SetWiFimodetostation(asopposedtoAPorAP_STA)

WiFi.mode(WIFI_STA);

//WiFI.begin([ssid],[passkey])initiatesaWiFIconnection

//tothestated[ssid],usingthe[passkey]asaWPA,WPA2,

//orWEPpassphrase.

WiFi.begin(WiFiSSID,WiFiPSK);

//UsetheWiFi.status()functiontocheckiftheESP8266

//isconnectedtoaWiFinetwork.

while (WiFi.status()!= WL_CONNECTED)

{

//BlinktheLED

Page 1

of 2

digitalWrite(LED_PIN,ledStatus);//WriteLEDhigh/low

ledStatus= (ledStatus== HIGH)?LOW:HIGH;

//DelaysallowtheESP8266toperformcriticaltasks

//definedoutsideofthesketch.Thesetasksinclude

//settingup,andmaintaining,aWiFiconnection.

delay(100);

//Potentiallyinfiniteloopsaregenerallydangerous.

//Adddelays allowingtheprocessortoperformother

//tasks whereverpossible.

}

}

void initHardware()

{

Serial.begin(9600);

pinMode(DIGITAL_PIN,INPUT_PULLUP);

pinMode(LED_PIN,OUTPUT);

digitalWrite(LED_PIN,LOW);

//Don'tneedtosetANALOG_PINasinput,

//that'sallitcanbe.

}

int postToPhant()

{

//LEDturnsonwhenweenter,it'llgooffwhenwe

//successfullypost.

digitalWrite(LED_PIN,HIGH);

//DeclareanobjectfromthePhantlibrary phant

Phantphant(PhantHost,PublicKey,PrivateKey);

//Doalittleworktogetauniqueishname.Appendthe

//lasttwobytesoftheMAC(HEX'd)to"Thing":

uint8_tmac[WL_MAC_ADDR_LENGTH];

WiFi.macAddress(mac);

String macID= String(mac[WL_MAC_ADDR_LENGTH 2],HEX)+

String(mac[WL_MAC_ADDR_LENGTH 1],HEX);

macID.toUpperCase();

String postedID= "Thing" + macID;

//Addthefourfield/valuepairsdefinedbyourstream:

phant.add("id",postedID);

phant.add("analog",analogRead(ANALOG_PIN));

phant.add("digital",digitalRead(DIGITAL_PIN));

phant.add("time",millis());

//Nowconnecttodata.sparkfun.com,andpostourdata:

WiFiClientclient;

const int httpPort= 80;

if (!client.connect(PhantHost,httpPort))

{

//Ifwefailtoconnect,return0.

return 0;

}

//Ifwesuccessfullyconnected,printourPhantpost:

client.print(phant.post());

//Readallthelinesofthereplyfromserverandprintthe

mtoSerial

while(client.available()){

String line= client.readStringUntil('\r');

//Serial.print(line);//Tryingtoavoidusingserial

}

Page 20 of 2

//Beforeweexit,turntheLEDoff.

digitalWrite(LED_PIN,LOW);

return 1;//Returnsuccess

}

This sketch accomplishes the same feat as that in our first example – it

posts some data to a data.sparkfun.com stream every 30 seconds. But

there’s one huge difference: sleep.

Notice there’s nothing in the loop() . The program halts when the

ESP.deepSleep(30000000) is called. After 30 seconds, when the ESP8266

wakes up, it’ll start running code back at the beginning of setup() .

If you put a multimeter in-line to measure the current draw, the Thing would

pull about 80mA for the ~5 seconds it takes to connect and post to Phant.

Then, while it sleeps for about 30 seconds, the current draw would be

around 8mA. An average of about 18mA per second.

In deep sleep mode, the Thing pulls about 8mA (that’s mostly the power

LED).

Most of the current draw in sleep mode is from the power LED indicator – if

you want to save even more juice, you may consider removing the LED (or

current-limiting resistor) or even cutting a trace. (Hint: cut the trace running

through middle of the ‘R’ in “PWR”.)

Using the Arduino Addon

If you’ve used Arduino in the past, there will be some new programming

schemes to get used to in ESP8266 land.

Pin Mappings

As with any other Arduino, the pin mappings printed on the board match the

pin you read or write to. The SDA and SCL pins can be referenced as 2 and

14 respectively.

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.

Yielding

This is one of the most critical differences between the ESP8266 and a

more classical 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.

Page 21 of 2

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 amazing creators of the ESP8266 Arduino libraries also implemented 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u

while (digitalRead(12)== HIGH)//Whilepin12isHIGH(nota

ctivated)

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

A lot of the core Arduino libraries have been re-written to work for the

ESP8266, including:

•Wire – The ESP8266 should work with any I C sensor you can throw

at it – just use the same Wire API calls you’re used to. There are a

few differences:

◦Pin definition: The ESP2866 doesn’t actually have any

hardware I C pins – those labeled on the Thing are the default,

but you can actually use any two pins as SDA and SCL.

Calling Wire.begin() will assume pins 2 and 14 are SDA and

SCL, but you can manually set them to any other pin by calling

Wire.begin([SDA],[SCL]) .

•SPI – The ESP8266 Thing can control an SPI bus using function

calls made standard by the Arduino SPI library.

◦An additional function to set the frequency –

SPI.setFrequency([frequency]) – is added. You may need

to call that in your setup to slow the clock down from its default

Page 2

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value. For example, SPI.setFrequency(1000000) will set the

SPI clock to 1MHz.

◦The MISO, MOSI, and SCLK SPI pins are hard-coded and

can’t be moved, they are:

Pin Number SPI Function

12 MISO

13 MOSI

14 (SCL) SCLK

15 CS

Using the Serial Monitor

GPIO0 – while perfectly capable as a digital I/O – serves a secondary

purpose as a bootload/run-mode controller. When the ESP8266 boots up, it

looks at GPIO0’s value to either enter the bootloader or start running the

current program:

GPIO0 Value ESP8266 Mode

HIGH (3.3V) Run Program

LOW (0V) Bootloader

To make it easy to program the ESP8266, we’ve tied GPIO0 to DTR (along

with RST). When your programmer begins to upload a sketch, it’ll pull DTR

low, in turn setting GPIO0 low and making the ESP8266 enter bootloader

mode.

Unfortunately, when you open a serial terminal, DTR usually goes low

again. So every time you open the Arduino serial monitor, it’ll cause the

ESP8266 to enter bootloader mode, instead of run-program mode. If you

open up the serial monitor, and all you see is a line of gibberish, you’ve

probably booted the ESP8266 into bootloader mode.

There are a few ways around this. We’ve added the DTR jumper on the

bottom of the board. You can cut the trace on the back and install a 2-pin

male header combined with a 2-pin jumper. If the jumper is present, the

board will be able to be programmed. Removing the jumper will enable

serial terminal mode.

Page 2

of 2

Or you can find a serial terminal program that allows control of the DTR pin

directly. RealTerm allows for this control – navigate to the “Pins” tab, and

click “Clear” next to “DTR.”

Unfortunately, this Windows-only solution is the only terminal program

we’ve found so far with such control. Your best bet may be to try to avoid

serial debugging whenever possible – that’s what LED’s are for, right?

(Tongue only kind-of in cheek.)

Resources & Going Further

An astoundingly awesome community has grown around the ESP8266. We

owe them big time for the amazing Arduino addon they’ve cooperatively

built. For all of your ESP8266 needs, we recommend checking out the

esp8266.com Community Forum. In addition to that, here are a few

ESP8266-related resources we’ve found incredibly helpful:

• ESP8266 GitHub User Repos – Tons of incredible tools can be found

here. From Crosstool (to compile your own Xtensa GCC, G++, etc.)

to the ESP8266 Arduino GitHub Repo

• ESP8266 Community Wiki – Related to the community forum, there’s

a good amount of information available in this wiki.

• NodeMCU Firmware and the NodeMCU Flasher – NodeMCU is a

popular firmware for the ESP8266. It implements a LUA-based

interpreter on the ESP8266 MCU.

• Espressif Board Forums – Espressif, the manufacturers of the

ESP8266, have a forum of their own. You can sometimes find

updated software development kit downloads, or other helpful links

here.

• Espressif GitHub Repos – Espressif is also somewhat active on

GitHub. They host a couple versions of the SDK here.

The ESP8266 Thing is open source hardware! If you need, or just want to

look at, the PCB design files, you can find them in our ESP8266 Thing

GitHub repository.

Going Further

Need a little project inspiration, now that you’ve got your ESP8266 Thing

up-and-running? Maybe some of these related SparkFun tutorials will help

spur some ideas:

Are You Okay? Widget

Page 2

of 2

With it’s deep sleep ability, the Thing is a great foundation for a WiFi-based

weather station, or a friendly, huggable, interactive plushy.

Weather Station Wirelessly

Connected to

Wunderground

Build your own open source, official

Wunderground weather station that

updates every 10 seconds over Wifi

via an Electric Imp.

Use an Electric Imp and

accelerometer to create an "Are You

OK" widget. A cozy piece of

technology your friend or loved one

can nudge to let you know they're

OK from half-a-world away.

Pushing Data to

Data.SparkFun.co

grab bag of examples to show off

the variety of routes your data can

take on its way to a

Data.SparkFun.com stream.

Using AT&T's M2X With the

CC3000

A set of tutorials and examples to

show how to connect an Arduino

and CC3000 to AT&T's M2X data

streams. We show how to post,

fetch, and delete data. The final

lesson is controlling an LED from an

M2X stream.

Page 2

of 2

201

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s://learn.s

arkfun.com/tutorials/es

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