ESP8266 Robotics Projects

Chapter 1. Getting Ready

Welcome to the exciting world of programming ESP8266 with Arduino core for ESP8266. This chapter introduces ESP8266 and a simple LED blink program using the Arduino core for the ESP8266 library.

In this chapter, you will learn the following topics:

The basics of ESP8266 and the module family
The original ESP8266 ESP-01
Applying regulated power to ESP-01
Connecting ESP-01 with computer through a USB to TTL serial console cable
Preparing the development environment by installing the Arduino core for the ESP8266 library
Writing a simple LED blink program using the Arduino core for ESP8266
Using AT commands
The overview of some robotics hardware and accessories

ESP8266EX

The ESP8266EX (Figure 1.1) is a single-chip microcontroller developed by Espressif (https://espressif.com/). It can be used to develop low-power, highly-integrated Wi-Fi solutions especially for mobile devices, wearable electronics, and the Internet of Things (IoT) applications. The main advantage of ESP8266EX is that it can give any microcontroller access to a Wi-Fi network. As an example, it can offload all Wi-Fi networking functions for Arduino just like the Arduino Wi-Fi shield:

Figure 1.1: ESP8266EX chip

The chip has the following great features:

Small size (5 mm x 5 mm)
Requires minimal external circuitry
Wide temperature range (-40°C to + 125°C)
All-in-one small package -SoC (integrates a 32-bit Tensilica MCU, standard digital peripheral interfaces, antenna switches, RF balun, power amplifier, low-noise receive amplifier, filters, and power management modules)
Low power consumption

ESP-01

ESP-01 is a small Wi-Fi module based on Espressif ESP8266EX that can give any microcontroller access to a Wi-Fi network. The ESP-01 module (Figure 1.2) is the basic and the most popular board of the ESP8266 module family. You should have an ESP8266 ESP-01 module to understand the basics of ESP8266 and build robotics projects.

This is a list of vendors that typically stock the ESP-01 modules:

SparkFun Electronics: https://www.sparkfun.com/products/13678
Adafruit Industries: https://www.adafruit.com/product/2282
Electrodragon: http://www.electrodragon.com/product/esp8266-wi07c-wifi-module/

Figure 1.2: The original ESP8266 ESP-01. Image courtesy of SparkFun Electronics (https://www.sparkfun.com)

The original ESP8266 ESP-01 has the following features:

Offloads all Wi-Fi networking functions from another application's processor
Self-hosting of applications
Only four pins interface, VCC-3V3, GND, TX, and RX
1 MB (8 MB) flash memory
Pre-programmed AT command set firmware
Supports APSD for VoIP applications and Bluetooth co-existence interfaces

Here is a list of all the ESP8266 boards of the ESP8266 module family at the time of writing:

ESP-01
ESP-02
ESP-03
ESP-04
ESP-05
ESP-06
ESP-07
ESP-08
ESP-09
ESP-10
ESP-11
ESP-12
ESP-12F
ESP-12-E/Q
ESP-12S
ESP-13
ESP-14

Board features and connections

The top of the ESP-01 board consist of the following things:

An ESP8266EX chip—Offloading all Wi-Fi networking functions
A Berg Micro BG25Q80A 1518 flash chip—Serial Peripheral Interface (SPI) flash memory
A printed Wi-Fi antenna—Transmitting and receiving Wi-Fi signals

Figure 1.3: ESP-01 top view

Connections

The original ESP8266 ESP-01 board has eight pins and comes without headers. You can solder regular wires with pins, but if you want to use it with a breadboard, you should attach headers:

Figure 1.4: ESP-01 pinout

GPIO0: Connects to pin 3 of the ESP8266
GPIO2: Connects to pin 5 of the ESP8266
TX: This is the transmitting line that connects to RX of another device
RX: This is the receiving line that connects to TX of another device
3V: This accepts regulated 3.3V DC from a regulator to power the board
GND: The ground pin
CH_PD: Chip select
RST: The reset pin

Connecting with a breadboard

You can use one of the following things to connect ESP8266 with a breadboard:

Using female/male extension jumper wires (https://www.adafruit.com/product/1954)
Using a 10-pin IDC breakout helper (https://www.adafruit.com/product/2102)

Power supply

The ESP8266 works only with regulated 3.3V. You can build a simple regulated power supply with an LD1117-3.3 linear voltage regulator. It can provide 3.3V at 800 mA. You can purchase a TO-220 package of the LD1117-3.3 for use with a breadboard. Figure 1.5 shows the circuit diagram for 3.3V output. You can supply 4-15V DC to V_in using one of the following sources:

7V LiPo battery
5V power bank
9V battery
5V "wall wart" power supply

Figure 1.5: 3.3V regulated power supply circuit diagram

Now, you can connect the power supply to ESP-01:

Connect Vout to the V_cc pin of ESP-01.
Connect GND to the GND pin of ESP-01.

Connecting through USB for flashing

ESP8266 ESP-01 doesn't have a built-in USB to serial conversion chip to directly connect to your computer through a USB cable for flashing programs. As a solution, you can use a USB to TTL serial console cable to connect ESP8266 to a computer. Figure 1.6 shows a USB TTL serial console cable from Adafruit (https://www.adafruit.com/product/954):

Figure 1.6: A USB to TTL serial console cable. Image courtesy of Adafruit Industries (https://www.adafruit.com)

The type A USB plug includes a USB to serial conversion chip and provides four wires to connect to your ESP8266ESP-01 board. Table 1.1 shows the functions of the four wires:

Color	Function
Red	Power
Black	Ground
White	RX
Green	TX

Table 1.1: Color codes and functions of wires

You can use the following steps to connect the USB to TTL serial cable with your ESP8266:

Connect the white RX wire of the cable to the TX pin of ESP8266
Connect the green TX wire of the cable to the RX pin of ESP8266
Connect the black ground wire of the cable to the GND pin of ESP8266
Connect the CH_PD pin of ESP8266 to the V_cc wire of the power supply

Note

Don't connect the red power wire because it is 5V.

Using a serial terminal program

The following steps will guide you how to use a serial terminal program to communicate and execute AT commands with ESP-01. In this example, you will use PuTTY, SSH, and a Telnet client for Windows to run AT commands through a serial port:

First, download the latest PuTTY MSI installer or binary from the following sources:
- MSI (Windows installer):
  - 32-bit: putty-0.70-installer.msi (https://the.earth.li/~sgtatham/putty/latest/w32/putty-0.70-installer.msi)
  - 64-bit: putty-64bit-0.70-installer.msi (https://the.earth.li/~sgtatham/putty/latest/w64/putty-64bit-0.70-installer.msi)
- Binary:
  - 32-bit: putty.exe (https://the.earth.li/~sgtatham/putty/latest/w32/putty.exe)
  - 64-bit: putty.exe (https://the.earth.li/~sgtatham/putty/latest/w64/putty.exe)

Open the PuTTY Configuration window by double clicking on putty.exe or the putty shortcut.
In the Serial line text box, type the COM port that is assigned to your ESP8266 board (Figure 1.7).
In the Speed text box, type 115200 as the baud rate.

Click on the Open button to make a serial connection:

Figure 1.7: The PuTTY configuration window

If you have provided the correct settings, the serial connection will establish between ESP8266 and your computer.
You can use the serial terminal window to issue AT commands for ESP8266 from your computer.

AT commands

Table 1.2 shows the complete set of AT commands that you can use with ESP8266:

AT command	Manual
`AT`	Attention.
`AT+RST`	Resetting the unit.
`AT+GMR`	Retrieving the firmware version ID.
`AT+CWMODE=?` `AT+CWMODE?` `AT+CWMODE=<mode>`	Setting operation mode: Client Access point Client and access point The access point functionality does not have a DHCP function and has only minimum functionalities. However, it will assign an IP address to the client and there is no way to do a manual IP, manual DNS, and other advanced IP functionalities. This unit only provides minimal functionalities.
`AT+CWJAP=<ssid>,<pwd>` `AT+CWJAP?`	Joining a network or just an access point.
`AT+CWLAP`	Retrieving the list of the visible network.
`AT+CWQAP`	Disconnecting from the current network connection.
`AT+CWSAP=<ssid>,<pwd>,<chi>,<ecn>` `AT+CWSAP?`	Setting up access point SSID, password, RF channel, and security scheme. The following is the security scheme: `0`: Open. No security. `1`: `WEP`. `2`: `WPA_PSK`. `3`: `WPA2_PSK`. `4`: `WPA_WPA2_PSK`.
`AT+CWLF`	Retrieving a list of assigned IP addresses.
`AT+CIPSTATUS`	Retrieving the current connection as socket client or socket server.
`AT+CIPSTART=?` `AT+CIPSTART=<type>,<addr>,<port> (AT+CIPMUX=0)` `AT+CIPSTART=<id>,<type>,<port> (AT+CIPMUX=1)`	Connecting to socket server (TCP or UDP).
`AT+CIPSEND=<length> (AT+CIPMUX=0 & AT+CIPMODE=0)` `AT+CIPSEND=<id>,<length> (AT+CIPMUX=1 & AT+CIPMODE=0)` `AT+CIPSEND (AT+CIPMUX=0 & AT+CIPMODE=1)`	Sending by connection channel and by specific length.
`AT+CIPCLOSE`	Closing the socket connection.
`AT+CIFSR`	Retrieving the assigned IP address when the unit is connecting to a network.
`AT+ CIPMUX=AT+CIPMUX?`	Setting a single connection (`AT+CIPMUX=0`) or multi-channel connection (`AT+CIPMUX=1`).
`AT+CIPSERVER= [,] (AT+CIPMUX=1)`	Starting at the specified port or stopping the server. The default port is `333`. `<mod>` is as follows: `0`: Close the socket server `1`: Open the socket server
`AT+CIPMODE=<mode>` `AT+CIPMODE?`	Setting transparent mode (data from the socket client will be sent to the serial port as is) or connection channel specific mode (`+IPD`,`<connection channel>`,`<length>`) segments. Data sent from the socket client will be broken into multiple unsolicited (`+IPD`,`<connection channel>`,`<length>`) segments. `<mode>`is as follows: `0`: Data received will be sent to the serial port with a `+IPD`,`<connection channel>`,`<length>` format. (`AT+CIPMUX=[0,1]`) `1`: Data received will be sent to the serial port as a data stream. (`AT+CIPMUX=0`)
`AT+CIPSTO=<time>` `AT+CIPSTO?`	Setting the automatic socket client disconnection timeout from `1` to `28800` seconds due to inactivities.
Packetized data from the unit	Unsolicited data packet (`+IPD`, `<connection channel>`,`<length>`).

Table 1.2: The ESP8266 AT command set (Source: SparkFun Electronics)

Using AT commands

Every AT command starts with the letters AT. Here's an example:

AT+GMR <CR>

Type the AT command AT+GMR and press the Enter key. Don't type <CR>. The CR indicates carriage return.

This will return the firmware version ID of the ESP8266 module, as shown in Figure 1.8:

Figure 1.8: Terminal output for the AT+GMR command

Likewise, you can run any AT command with the PuTTY terminal to execute on ESP8266 through the serial connection.

Using the Arduino IDE

The Arduino IDE provides an easy way to write sketches for Arduino and other development boards. You can use ESP8266 with the Arduino IDE. First, install the ESP8266 board package on Arduino IDE.

The ESP8266 also supports the following development environments:

Use a simple Notepad/GCC setup
Fine-tune an Eclipse environment
Use a virtual machine provided by Espressif

Installing the Arduino core for an ESP8266 Wi-Fi chip

The Arduino core for ESP8266 includes a set of libraries to do the following things with your ESP8266 Wi-Fi module:

Communicate over Wi-Fi using TCP and UDP protocols
Set up HTTP, mDNS, SSDP, and DNS servers
Perform OTA updates
Use a filesystem in flash memory
Work with SD cards, servos, SPI, and I2C peripherals

It also allows you to write sketches for ESP8266 with the core Arduino functions and libraries. You can run the sketches directly on ESP8266 without using an external microcontroller board:

Open the Arduino IDE and on the menu bar select File | Preferences.

Type the URL http://arduino.esp8266.com/stable/package_esp8266com_index.json for the ESP8266 board manager package for Arduino in the Additional Boards Manager URLs text box and click on OK to close the dialog box (Figure 1.9):

Figure 1.9: The Arduino IDE preferences

Open the Boards Manager by selecting Tools | Board | Boards Manager. You should see a new entry in the list titled esp8266 by ESP8266 Community (Figure 1.10):

Figure 1.10: The Arduino IDE Boards Manager

At the time of this writing, the Arduino core for ESP8266 Wi-Fi chip supports the following boards:
- Generic ESP8266 Module
- Olimex MOD-WIFI-ESP8266(-DEV)
- NodeMCU 0.9 (ESP-12 Module)
- NodeMCU 1.0 (ESP-12E Module)
- Adafruit HUZZAH ESP8266 (ESP-12)
- ESPresso Lite 1.0
- ESPresso Lite 2.0
- Phoenix 1.0
- Phoenix 2.0
- SparkFun Thing
- SweetPea ESP-210
- WeMos D1
- WeMos D1 mini
- ESPino (ESP-12 Module)
- ESPino (WROOM-02 Module)
- WifInfo
- ESPDuino
Click on the Install button to install it on your Arduino IDE. This will take a few minutes to install, depending on your internet speed.
Click on Close to close the Boards Manager dialog box.
Select Tools | Board: "Generic ESP8266 Module" | Generic ESP8266 for board type.
The upload speed should be 115200; however, you can increase it to a higher value by clicking on Tools | Upload Speed and selecting a value greater than 115200.

Hello world

Now, you will write your first program (sketch) for ESP8266 with the Arduino IDE to blink a LED connected to PIN 2 of ESP8266.

You'll need the following things to build the circuit:

One LED (any color)
One 1 kilo ohm resistor
3V regulated power supply

Connect the components together, as shown in Figure 1.11:

Figure 1.11: The LED blink circuit hook up

Listing 1-1 – Blink a LED

Using your Arduino IDE, type the code as shown in the Listing 1-1:

#define ESP8266_LED 2void setup() {  pinMode(ESP8266_LED, OUTPUT);}void loop() {  digitalWrite(ESP8266_LED, HIGH);delay(500);digitalWrite(ESP8266_LED, LOW);delay(500);}

Then, verify the sketch by clicking on the Verify button. Finally, upload the program by clicking on the Upload button. This will take a few seconds to complete. After completing the flashing, the LED will start to blink.

Using chassis kits and accessories to build robots

Chassis kits provide everything to build robots with most microcontroller boards. You'll use the following chassis kits to build projects.

Mini 3-Layer Round Robot Chassis Kit

The 3-Layer Mini Round Robot chassis Kit (Figure 1.12) includes the following things you need to build the shell of a two-wheel drive mobile platform robot:

Two drive motors
Two wheels
One plastic caster ball
Anodized aluminum frames and all mounting hardware for assembly

You can purchase a kit from Adafruit Industries (https://www.adafruit.com/product/3244) to work with projects that will be discussed in Chapter 2, Building a Mini Round Robot with Original ESP8266, Chapter 3, Using Encoders, and Chapter 4, Building a Mini Round Robot with the Feather HUZZAH ESP8266:

Figure 1.12: A Mini Round Robot Chassis Kit. Image courtesy of Adafruit Industries (https://www.adafruit.com)

Zumo chassis kit

The Zumo chassis kit (Figure 1.13) allows you to build tracked robots that run on continuous tracks instead of wheels. Tracked vehicles can be used for:

Construction vehicles
Military armored vehicles
Unmanned ground vehicles

The Zumo chassis kit includes the following things:

Zumo chassis main body
1/16" black acrylic mounting plate
Two drive sprockets
Two idler sprockets
Two 22-tooth silicone tracks
Two shoulder bolts with washers and M3 nuts
Four 1/4" #2-56 screws and nuts
Battery terminals

You can purchase a kit from Pololu (https://www.pololu.com/product/1418) to work with the project that will be discussed in Chapter 5, Line-Following Zumo Robot:

Figure 1.13: A Zumo chassis kit. Image courtesy of Pololu (https://www.pololu.com)

Romi chassis kit

The Romi chassis kit (Figure 1.14) includes the following things you need to build a two-wheel drive robot:

One black Romi chassis base plate
Two mini plastic gearmotors (120:1 HP with offset output and extended motor shaft)
A pair of black Romi chassis motor clips
A pair of white 70 × 8 mm Pololu Wheels
One black Romi chassis ball caster kit
One Romi chassis battery contact set

You can purchase a kit from Pololu (https://www.pololu.com/category/202/romi-chassis-and-accessories) to build the project that will be discussed in Chapter 6, Building an ESP8266 Robot Controller:

Figure 1.14: A Romi chassis kit - Black. Image courtesy of Pololu (https://www.pololu.com)

Mini robot rover chassis kit

The mini robot rover chassis kit (Figure 1.15) includes the following things needed to build the shell of a two-wheel drive robot:

Two wheels
Two DC motors in MicroServo shape
One support wheel
One metal chassis
One top metal plate with mounting hardware

Figure 1.15: A mini robot rover chassis kit. Image courtesy of Adafruit Industries (https://www.adafruit.com)

You can purchase a kit from Adafruit industries (https://www.adafruit.com/product/2939) to build the project that will be discussed in Chapter 7, Building a Gripper Robot.

Rover 5 robot platform

The Rover 5 robot platform (Figure 1.16) allows you to build a four-wheel drive tracked robot. The kit includes the following things:

Adjustable gearbox angles
4 independent DC motors
4 independent Hall-effect encoders
Thick rubber tank treads
6 x AA battery holder
10 Kg/cm stall torque per motor

Figure 1.16: A Rover 5 robot platform. Image courtesy of Pololu (https://www.pololu.com)

You can purchase a kit from Pololu (https://www.pololu.com/product/1551) to build a project that will be discussed in Chapter 8, Photo Rover Robot.

Wheel encoder kit

The wheel encoder kit (Figure 1.17) allows you to measure the speed or distance that the chassis travels. You'll learn how to connect the wheel encoder kit to any wheeled robot in Chapter 3, Using Encoders:

Figure 1.17: A wheel encoder kit. Image courtesy of SparkFun Electronics (https://www.sparkfun.com)

Parallel Gripper Kit A - Channel mount

A gripper can be connected to a robot to allow grip objects. Figure 1.18 shows a Parallel Gripper Kit assembled. You will need any standard size Hitec or Futaba servo to integrate with the gripper kit. You can purchase one from SparkFun Electronics (https://www.sparkfun.com/products/13178):