Anybody used one of those ebay LCD display serial interface boards?

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kk6gm
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Posted by kk6gm: Fri. Aug 24, 2018 - 08:53 PM
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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).  

 

 

 

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Bronze Markdavid.prentice
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Posted by david.prentice: Fri. Aug 24, 2018 - 09:07 PM
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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.

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jgmdesign
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Posted by jgmdesign: Fri. Aug 24, 2018 - 09:20 PM
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Google Davide Gironi AVR I2C LCD. He has made an excellent driver using Peter fleurys library

Jim

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

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Last Edited: Sat. Aug 25, 2018 - 12:55 AM
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kk6gm
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Posted by kk6gm: Fri. Aug 24, 2018 - 09:24 PM
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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.

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kk6gm
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Posted by kk6gm: Fri. Aug 24, 2018 - 09:29 PM
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jgmdesign wrote:
Decide Gironi AVR I2C LCD

Thanks for the pointer

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Bronze Markdavid.prentice
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Posted by david.prentice: Fri. Aug 24, 2018 - 09:45 PM
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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
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valusoft
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Posted by valusoft: Sat. Aug 25, 2018 - 12:57 AM
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Decide Gironi AVR I2C LCD

That would be "Davide"

Ross McKenzie, Melbourne Australia

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jgmdesign
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Posted by jgmdesign: Sat. Aug 25, 2018 - 12:58 AM
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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

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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