Thursday, January 1, 2015

ESP8266 wifi (ESP01) IoT control a lamp

Internet controlled AC Appliances with ESP8266 wifi ESP01
ESP8266 wifi (ESP01) IoT control a lamp

ESP8266 is a very low cost WiFi transceiver that can be added to any existing microcontroller based setups via UART (serial link) to enable the system to communicate over the Internet via WiFI. In this guide, the objective is to achieve the epitome of IoT inspired setup; that is to control an AC (Alternate Current) electrical appliance over the Internet using ESP8266. The outcome of this setup: a command to be sent from a website through the WiFi network to ESP8266 with Arduino Mega to turn on an AC lamp for 2 seconds. The AC lamp is a place holder for any electrical device to be "Internet Enabled".

The following diagram describes the necessary parts and setup for this apparatus. On the left is an Multiplug modified with SSR, In the middle is Arduino Mega. On the breadboard is ESP8266 and sparkfun logic level shifter. Arduino Mega Pin7 is for SSR, Serial2 pin16,17 for UART with ESP8266, and Serial0 for USB serial monitor.

An IoT controlled AC appliance can be quite daunting to construct. Setting up such apparatus requires cross domains knowledge such as computer networking, electrical, electronics, programming, administering software on the Operating Systems (linux) of a server (or just another computer), and the often unspoken (and hair pulling moments) troubleshooting techniques. Combining several key building blocks to this setup can be overwhelming. Not to worry, because the divide and conquer approach can be adopted to R&D (Replicate & Duplicate) this setup. Which has been conveniently divided, constructed, and described in the following sections. It is highly recommended to construct the building blocks/modules and tested for functionality, prior to assembling this apparatus.

The necessary building blocks/modules of this setup is broken down into the following
1. Computer Networking: Setting up a WiFi Access Point/Router. Setup wifi security, either OPEN, WEP or WPA. DHCP for the connecting clients (the computer and ESP8266). PING-ing the devices on the network. DMZ for TCP server (if necessary, use for Internet side to access)

2. Electrical  & Electronics: Setting up the IoT inspired SSR Multiplug, and setting up ESP8266 with Arduino Mega; connecting the SSR Multiplug to ESP8266 with Arduino Mega

3. Programming (software): Firmware for ESP8266 on Arduino Mega to control the SSR Multiplug upon receiving a command. Server side software for sending a packet (that contains the command) from a TCP server through TCP/IP  to the ESP8266 port 8266.

4. Administering OS (linux): install the necessary software packages Tornado, Python, and Pip.

5. Testing/Troubleshooting

the following diagram describes the apparatus getting ready to be tested.

The following video describes the operation of clicking on the website to send a command via WiFi to ESP8266 with Arduino Mega to turn on the AC lamp for 2 seconds.

Computer Networking
Parts needed: WiFi Router
Note: ESP8266 defaults to IP address of 192.168.1.XYZ out of the box. Both the ESP9266 with Arduino Mega and the server will connect to this WiFi Router network of 192.168.1.XYZ/24. Ensure that firewall rules are removed temporarily or a permit all are applied during testing.

1. setup WiFi Router to issue IP Address via DHCP using the IP address pool 192.168.1.XYZ; subnetmask set to /24 e.g With the router available on hand, it is configured to allocate IP address in the range of to 99 to PC. Just a matter of personal preference.
2. setup WiFi security, OPEN, WEP, or WPA. Current setup on existing WiFi Access Point/Router. For the sale of simplicity during testing, OPEN can be configured. For long term usage, it is recommended to configure for WPA.
3. Configuration on different brands of WiFi Router might be slightly different from one and another. RTFM.
Alternative: Modify the settings in ESP8266 to suit the network address on the existing WiFi Router network.

Electrical & Electronics
Parts needed: IoT inspired Multiplug modified with SSR; ESP8266 connected to Arduino Mega.

Th details steps of modifying a multiplug with SSR is available on instructables or here

The details steps of connecting an ESP8266 to Arduino Mega is available on instructables or here

once these two building blocks are ready, connect pin7 of arduino mega with the signal pin of the SSR. VCC on the SSR to 5V on arduino and GND to GND on arduino. Ensure all components are connected to the common ground.

Software (Programming)
There are 2 pieces of software necessary for setting up this apparatus. One, the firmware that is residing in the Arduino Mega with ESP8266 and controlling the SSR in the multiplug, and the other is the software residing in the linux server to send a "command" via a website.

The firmware deals with the necessary parameters of ESP8266 to connect to a WiFi network, and waits for the "command" from the server via TCP port 8266. The port number is a deliberate choice, but it is not recommended to choose ports that are in the "well known" e.g ports number < 1024. Choose ports that are in the ephemeral ports region if it pleases you. The "command" is a keyword sent by the server side software, e.g "LED".  Upon receiving this keyword by the ESP8266 and Arduino Mega, pin7 is held high for 2 seconds and then held low for testing purposes. The "command" is a variable that can be customized. Out of convenience, and also the discovery of the LEDServer software on github, the keyword "LED" is used.

The server side software is obtained from github out of convenience for testing. Many thanks! Please follow the URL below for a detailed descriptions on the static html page and python. Every time the button send is pressed, the string "LED, R, G, B" is sent to ESP8266. Essentially, only the "send" button and the keyworkd "LED" are used by this setup in particular. The original intention of this server side software is to use the variable R, G, B that is of type integer measuring from 0-255 for setting the colour of neopixel.

Alternatively, and for the sake of simplifying the server side software for testing there is an opensource tool sockettester v3.0 can be used. URL here
The ESP8266 LED Server software is used as an example for the sake of complicity of the explanations of this IoT setup.

code for firmware here:

code for server software on linux here

Administering OS
Since the chosen server side software mentioned earlier runs off linux; there are several pre-requisite steps needed. In this setup, a virtual machine running ubuntu 14.04 desktop is assumed, and a USB WiFi adapter is connected to this virtual machine. The server side software requires python, Tornado webserver that can be installed via pip.

1. Configure USB WiFi adapter to connect to the WiFi router. This step varies, depending on the WiFi security setup such as OPEN, WEP or WPA.

Existing WiFi network is using WPA, so it has to be set up accordingly.

apt-get install wpasupplicant wireless-tools

nano /etc/network/interfaces

#add in the following ssid and wpa password
auto wlan0
iface wlan0 inet dhcp
wpa-ssid ______
wpa-psk _______


2. install pip (if it is not installed)
sudo apt-get install python-pip

3. install tornado (if it is not installed)
pip install tornado

4. execute the server side software as per the instructions in github. The following diagram describes this operation.


check IP address of the devices from WiFi Router's management console, and ping the devices. The following screenshot describes this operation.

Test ESP8266 for functionality using AT commands.
The following diagram describes the commands used for testing.

Savour the moment

1 comment:

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