In the previous post we’ve seen how to initiate ESP module & use AT commands.In this post TCP CLIENT mode operation is explained.

ESP8266 WIFI module has 3 modes of operation.

ST  – Station mode in which ESP acts as a device & connects to an existing Access point.

AP – Access Point mode where the ESP itself acts as AP & other devices like Mobile can connect to it.

Both – ST & AP both mode is allowed in ESP.The mode of operation is set by the AT command

AT+CWMODE = 1 for ST mode , 2 for AP mode & 3 for both.

As we’re testing ESP on STation mode , issue the command

AT+CWMODE=1

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To communicate with a webpage , we need to start a server with ESP module.You need to set multiple connections using command

AT+CIPMUX=1

This initiates the server for a Webserver.

Next we start the server at HTTP port 80 using command ,

AT+CIPSERVER=1,80

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To close the server the command is AT+CIPSERVER=0 followed by a Reset AT+RST

To get the STATION IP address ,

AT+CIFSR

The module returns the Station IP address , 192.168.1.3 .

If the CWMODE is set to 3 , you’ll get 2 IP address , one for AP & another for Station mode.We need the station IP address for Client mode operation.

Open your web browser & type in the address 192.168.1.3

The browser sends a HTTP GET request which is displayed on the putty window where ESP module is connected.The host IP address & the user agent (your web browser name) are displayed.

After you get OK  type in the command

AT+CIPSEND=0,30

This command is to send 30 characters through channel 0 .Use the channel number which is displayed as CONNECT while a request is received from the browser.

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Now you get a  >  symbol , after which you’ve to type in 30 characters.

The module will wait till you type in 30 characters & finally displays SEND OK.

You’ve to type characters within the Timeout limit.Otherwise the link will be closed.

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Now the characters are sent to the Web browser.

But the browser is still waiting for the channel to be closed.

Type in AT+CIPCLOSE=0

Here use the channel number ( 0) where the connection was established .

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Once the channel is closed , you get the characters displayed on the browser.

HTML tags can be used to send characters

AT+CIPSEND=0,30

>

HELLO WORLD !!!!!

The above one displays characters using HTML tag type Heading 1.

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To close the server the command is AT+CIPSERVER=0 followed by a Reset AT+RST

For testing 2 way communication , open another instance of PUTTY .

Select connection type as TELNET & Port 80.

Type in the host address , which you get by AT+CIFSR command in ESP window.

Click on open.

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Type some characters inside TELNET window .You get these inside ESP window

+IPD,0,17:HELLO….

0 is the channel of communication & 17 is the number of characters received.

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From within ESP window type AT+CIPSEND=0,20

ESP will wait till you type 20 characters.

On TELNET window the characters are received.

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Watch this support video :

ESP WIFI Modules available at :

cooltext753793315  cooltext753790696

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