Let's Make Robots!

LCD and picaxe

I am just beginning to research lcd boards. I have been told to get the 16 x 2 Alphanumeric LCD Module,  would this work, (sorry for font) http://www.robotshop.com/parallax-2x16-parallel-lcd.html  


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bad link.


And why wouldn't it work?

This LCD display uses 4 or 8-bit parallel interface, so you need a lot of pins to communicate with it... you can make it work but a serial comms display would be a lot easier.

also im using a picaxe 28x board if that helps, and i have pins to play with.


what is a serial comm display? im trying to know as much as I can before I buy it. thanks for the help, do you have a product in mine? and is the 16x2 too big or is it a good size? 

I looked at sparkfun, before and it looked good so I guess that confirms my choice. thanks.

ok thanks for the sites and new parts of the manual I havent read yet, just learning right know so I know what to buy when I can. Thanks for help, Chris and others

Even in 4-bit mode that module will require seven pins on your controller. IMO I think it's easiest to work with an LCD that has a serial or I2C backpack on it. A backpack is essentially another chip that talks to your microprocessor and handles all the LCD tasks. This avoids having to use a bunch of pins to talk to the LCD directly. It also saves on a lot of code you would have to write up yourself.

I believe the LCD controller offered by PHAnderson is right up your alley:


It uses a simple three-wire serial interface and he even includes some sample code for inspection. It's got some interesting programming for big digits on 20X4 displays as well as the typical display for the 16X2 sized units. He sells the backpack and the LCD or you can get the backpack and buy the LCD elsewhere. They are pretty ubiquitous.

There are also I2C LCD modules out there but they tend to run a little more pricey. Unless you're pin-greedy or are already using I2C for other things I'd just go serial. If you want to really keep it on the cheap and can spare a lot of pins (eight I think?), this is for you:


This is a bare bones, LCD only unit. No backpack. You work the display directly through your processor. There is some code for you to leaf through to get the idea how the interface functions. Tedious and pin intensive, but cheap cheap cheap.

thanks for all the info and the ebay lcd. i like websites that are popular and i have accounts to already. 

Careful with the SparkFun SerLCD V2.5 though, if that's what you get. I bought one and while I have it working right now, it doesn't save my baudrate changes. Also, another thing that tripped me up is that the default baudrate is T9600, not N9600 like I believed. Aside from that, it's a pretty neat piece of hardware.