I2C LCD interface
SKU
I2C-LCD-INTERFACE
In stock
$2.95
Overview
I2C LCD interface, IO expander.
Uses the well-known PCF8574P.
This is a general purpose eight-bit input/output chip.
Female to female
Male to female
Female to male
This is a general purpose eight-bit input/output chip.
Here is a library recommended by Chris Molloy of Kingston, he has used it with a 2 x 16 LCD display and the I2C interface. Link to Zip
The hard-coded address is: 0100.A2A1A0
The 0100 part is hard-coded in the PCF8574P.
The bits A2 A1 A0 are for you to choose. Make these bits one or zero by tying the corresponding pins to Vcc or Ground.
The PCB has 3 sets of pads, when no jumper is in place, its a 1, when jumpered its a 0.
Philips produces two variants of this IC: the PCF8574 and the PCF8574A. The only difference is the I2C chip address!
PCF8574 0100.A2A1A0
PCF8574A 0111.A2A1A0
The connections are as follows:
P8574 LCD Bit Location
Pin 4 - Pin 4 D0 RS
Pin 5 - Pin 5 D1 R/W
Pin 6 - Pin 6 D2 Enable
Pin 7 not used/Backlight D3
Pin 9 - Pin 11 D4 DB4
Pin 10 - Pin 12 D5 DB5
Pin 11 - Pin 13 D6 DB6
Pin 12 - Pin 14 D7 DB7
Even thou this is configured as an output device for LCD modules, it can also be read making it a simple I2C input port.
Turns out the layout is not simple, bit locations versus display pins are as follows:
Bit location 0 is LCD display pin D3
Bit location 1 is LCD display pin RS
Bit location 2 is LCD display pin E
Bit location 3 is LCD display pin D4
Bit location 4 is LCD display pin D6
Bit location 5 is LCD display pin RW
Bit location 6 is LCD display pin Back Light
Bit location 7 is LCD display pin D5
We have a few cable styles 20 cm, we do have 30 cm also:
The blue Potentiometer adjusts Contrast. If you don't see any characters, just give it a turn one way or the other. Start clockwise and back down to where the characters are bright and the background does not have boxes behind the characters.
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