I just ordered a couple of these boards that are flooding ebay. Thought they'd be interesting to play with.
https://www.ebay.com/itm/1X-IIC-...
Anybody have any experience with them? Any links to documentation (not good, I've heard).
Anybody used one of those ebay LCD display serial interface boards?
Author
Message
Go on. These backpacks have been available for about 10 years.
They work nicely in Arduino.
They are supported by Codevision.
Several people have published C code for any Mega chip with AS7.
They are designed for LCDs. But you can use them as any Port Expander.
David.
Google Davide Gironi AVR I2C LCD. He has made an excellent driver using Peter fleurys library
Jim
Last Edited: Sat. Aug 25, 2018 - 12:55 AM
david.prentice wrote:
Go on. These backpacks have been available for about 10 years.
Not surprised, seems like an obvious thing to make. I don't know what chip is on them out of the box, but might be fun to put an AVR on one if the PCB allows it.
jgmdesign wrote:
Decide Gironi AVR I2C LCD
Thanks for the pointer
They are just PCF8574 I2C Port Expander.
You simply wobble the bits to drive the HD44780 LCD in 4-bit mode.
It is incredibly inefficient way to control the LCD. But hey-ho, humans read fairly slowly. It is very convenient to save wires by using the I2C bus.
If you want an efficient way to drive LCD, you use a separate AVR e.g. MicroCarl's backpack. Or a separate PIC e.g. Digole backpack.
David.
Last Edited: Fri. Aug 24, 2018 - 09:46 PM
Decide Gironi AVR I2C LCD
That would be "Davide"
The downside of using MicroCarls backpack is that you lose your USART. If you have two USARTs and can afford losing one sure, otherwise nothing wrong with using the TWi interface. As you said humans read slowly so the TWI is not a big deal. The speed difference I can see is negligible.
Jim