Let's Make Robots!

20x4 Serial + I2C LCD

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Vendor's Description: 

An other cool component from web4robot



see it in actionhttp://www.youtube.com/watch?v=5JkdyQWzqT4


Serial + I2C LCD                           datasheet is here

Serial is TRUE serial  (0 is low, 1 is high)

serial/I2C choice is made with the jumper on the back    (closed : SERIAL ,  open : I2C )

default baud rate is 9600

"reset to factory default"  : power off , changer jumper state, power on, power off, change jumper state, power on


my experience :

As the Picaxe08 max. baudrate is 2400,  and the LCD default is 9600,  I had to use my BS2 (boebot)  (BS2 can go up to 19200bps)

(moreover, I had no MAX232 to do it with my laptop)

This was done easily after I understood the T_ and N_ concepts of TTL serial connections

Every command is prefixed with 0xFE, then the command code, then a value (can be multiple bytes)

for example, the config to 2400bps was [0xFE,0x02,0x01]

0xFE : prefix

0x02 : command : change baudrate

0x01 : 2400 baud          (2 is 4800bps,  3 is 9600bps,  4 is 19200bps )


Any non-prefixed data is displayed on the screen

I did'nt use the I2C or keypad functions yet,  but it seems easy to use




web4robot pages says :


Serial LCD includes the standard LCD module and serial controller to provide a serial
communication interface for your microcontroller  or PC. The serial controller takes care of all
commands between LCD and your microcontroller and uses only two lines for
The simple command structure allows text and bar graphs to be displayed on the screen.
Provision is made for up to 8 user-defined characters. The module includes also the 4x4 matrix
keypad control.
The LDC backlight and contrast may be adjusted under program control to compensate for
differing lighting conditions and viewing angles.

The module supports 2 interfaces:

wavySphere_blue.gif       Serial TTL interface (2400, 4800, 9600, 19200 BAUD RATE)
wavySphere_blue.gif        I2C interface

Key Features

wavySphere_blue.gif Communicate over I2C or Serial TTL interface with software controlled speed
wavySphere_blue.gif 80 Byte buffer for messages received via communication interface
wavySphere_blue.gif Up to 8 custom characters can be defined
wavySphere_blue.gif Built in commands for drawing Bar Graphs
wavySphere_blue.gif User configurable start up screen
wavySphere_blue.gif LCD Backlighting controlled via software, has 254 brightness levels
wavySphere_blue.gif LCD Contrast controlled via software, has 254 contrast levels
wavySphere_blue.gif Keypad encoder for a keypad up to 16 keys (4 rows by 4 columns)
wavySphere_blue.gif Save the basic settings in module internal EEPROM

Click here to see the Serial LCD Manual.

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.


What are the benefits of I2C against serial, or vice versa? I've been crawling the web but its filled with too much technical jargon about how they work. I just need to justify which method I choose for a college project. In the case of this LCD, are there any deciding factors in choosing how to communicate with it?





I dont't really see benefits about I2C, serial connection allows using a single data wire for unidirectionnal communication.

Which is great when using silly little 8 pins chips like the picaxe 08.

Hi Drixx,  I actually bought mine on ebay ;)

but why would'nt we trust them... with the tons of stuffs I've already bought from all around the world with no single problem 

Hi ndupont!

What are your experince with www.web4robot.com?

It sure is a cool LCD display but I think the home page looks a little "home made" :)

Have you always got your shipment without any trouble?


Dennis L