I2C Understanding

ajward

Hi All...

I just bought a 4 x 20 LCD display with an I2C interface. I've Googled for the protocol for sending data to the display, but I'm just not getting it. Anyone have any tips for simplifying this?

Any guidance is appreciated.

Amanda

stamptrol

Hi Amanda,

The Stamps of the 2p, 2pe, and 2px series have built in commands for the 12c protocol and I've used them several times.

Have a look in the Stamp IDE help files for more details. Other than usually needing pull-up resistors on the clock and data lines, most problems are related to getting the instructions right for the device you're talking to.

Cheers,

SRLM

What's the LCD model number?

Genetix

Amanda,

Jon Williams wrote several Nuts & Volts articles on I2C with the BS2; They are 81, 85, and 115.
http://www.parallax.com/downloads/nuts-and-volts-basic-stamps-volume-3
http://www.parallax.com/downloads/nuts-and-volts-basic-stamps-volume-5

You will find that any Spin code he's written starts with jm_, such as jm_i2c_demo, which stands for Jon "JonnyMac" McPhalen.
If you scour the forums though you will see code he posts here and there.
http://obex.parallax.com/object/311
http://obex.parallax.com/object/155


I know you are playing with Propeller C, so have you looked at this tutorial?
http://learn.parallax.com/propeller-c-simple-protocols/diy-i2c

Here is some I2C example code for both the BS2 and the Propelller.
http://learn.parallax.com/KickStart/29133
http://learn.parallax.com/KickStart/27911

davejames

ajward wrote: »

...but I'm just not getting it. Anyone have any tips for simplifying this?

Hi Amanda,

Are you saying that you don't understand the I2C protocol itself?

Or are you saying that you do understand the I2C protocol, but do not understand how to implement it on the microprocessor that you're using?

SRLM

I'm guessing that it's a question on the actual LCD, not the I2C protocol or host microcontroller. The popular I2C LCDs have pretty poor documentation. I was looking into this last week since I'll be using a 4x20 I2C LCD I bought off of Amazon soon.

Here's a page that looks interesting: http://arduino-info.wikispaces.com/LCD-Blue-I2C

JonnyMac

Since my name has been bandied about, I've attached Propeller code for a common I2C LCDs. I've tested it with a 2x16, but it should be fine with any. Those LCD backpacks tend to use the PCA8475 IO expander to connect to the LCD. My code includes child objects for the PCA8475 and basic I2C communications.

And yes, Jon McPhalen is the artist formerly known as Jon Williams.