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I have ESP8266-01 this model

enter image description here

I Updated the frimware to nodeMCU and uploaded the web server code and tested by blinking led via web browser. Now I want to test that if I can send text data from web browser to ESP8266 and show that text on LCD screen similer to thi one

enter image description here

I know how to operate this LCD and display text on this LCD but my problem is that in this ESP8266 there are only to GPIO pin GPIO0 is for uploading frimware and GPIO2 is that free for send signal to outer device. I have not much knowladge about electronics so is there any way to achive this with minimum extra components if required.

Update:-

I found some link where they are showing its working but I am not able to figure it out how.

here are the links

  1. ESP8266 WITH 16X2 I2C LCD

  2. Image

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  • \$\begingroup\$ Use a module with more exposed pins. \$\endgroup\$ Sep 26, 2015 at 3:31
  • \$\begingroup\$ but why when I can achive this with same module ? \$\endgroup\$ Sep 26, 2015 at 3:46
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    \$\begingroup\$ You don't have enough pins; you will need external parts. \$\endgroup\$ Sep 26, 2015 at 3:47
  • \$\begingroup\$ Yes I am asking about what parts I'll required \$\endgroup\$ Sep 26, 2015 at 3:57

2 Answers 2

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With only a single gpio, you either need a one-wire port expander, or use the serial port to a serial backpack for a lcd. The two projects you link to use PCF8574 i2c port expanders. These need two pins, one for data and another for clock.

An expander is a IC that takes one protocol like i2c, spi, or otherwise, and provides a number of gpio. Like a middle man when you don't have enough pins free.

The PCF8574 for example is one of the first i2c port expanders providing a simple 8 bit interface, perfect for a lcd in 4 bit mode.

If you really only have one pin available, if the firmware can do the timing required for One-Wire, that may be an option. Otherwise you will need an esp board with more gpio available.

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  • \$\begingroup\$ Thanks I realy expecting someting like this can you please explain more about expender and where to buy ? \$\endgroup\$ Sep 26, 2015 at 4:08
  • \$\begingroup\$ An expander is a IC that takes one protocol like i2c, spi, or otherwise, and provides a number of gpio. Like a middle man when you don't have enough pins free. \$\endgroup\$
    – Passerby
    Sep 26, 2015 at 4:11
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    \$\begingroup\$ The PCF8574 for example is one of the first i2c port expanders providing a simple 8 bit interface, perfect for a lcd in 4 bit mode \$\endgroup\$
    – Passerby
    Sep 26, 2015 at 4:14
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It is actually possible all four pins, take a look at this:

http://www.forward.com.au/pfod/ESP8266/GPIOpins/ESP8266_01_pin_magic.html

and this:

https://arduinodiy.wordpress.com/2016/10/11/using-the-4-pins-of-the-esp8266-01/

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  • \$\begingroup\$ Why the downvote? And what is the problem in using a cheap i2c adapter to drive the LCD? \$\endgroup\$ Jun 12, 2017 at 4:17

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