AVR MCU as GLCD controller ?

[aliyesami]

since very few GLCD I2C libraries are out there for arduino I was thinking why don't people use an AVR MCU e.g atmel328P as a GLCD controller? wouldn't it be so easy to just connect the display parallel data bus to this AVR and then send the display commands from the main board using I2C ?

 

[andre_luis]

The proposal to designate Atmel328P strictly dedicated to perform interface to a I2C LCD module seems a little wastage.
That´s because most microcontrollers have already built-in hardware I2C modules which allows to do that without significant core processing consumption.

Other important remark is the synchronous nature of I2C protocol, becoming less critical the timing requirements on interfacing to the module.



+++

 

[aliyesami]

but considering the cost of an AVR these days like I bought mine for couple of dollars , shouldn't be a waste money wise right?
I didn't understand the second part of your reply . it would not work as a controller ?

 

[andre_luis]

Hi,

I was just considering the cost factor, but really, if you want to gather all the low level GLCD commands packed in some macro functions easier to work with at firmware side, in fact this proposal may be a good option, and it is even found at some designs, on what a dedicated board is used to interface to the module.

If you consider using this Atmega based interface board as an OEM module, it brings some design advantage, releasing main core processor to face to a massive protocol handling, thus managing access to GLCD with high level API driver routines.

However, if you are considering to design this board as a commercial product, and not to apply on same design house, could encounter some issues related to development scope. For instance, if this board is applied at some specific area ( e.g. medical ), we need some special characters which could be drawn and updated quickly to the interface board, once is at the same company, differently if purchased as some standard line product.

Another issue concerns to supply chain scope: If you adopt not the original GLCD, but also an interface board, your design will be tied to this customized product, avaliable at only this company.


+++

 

[aliyesami]

thanks for your valuable insight !

 

[bigdogguru]

Actually, there are several on the currently on the market, offering TTL UART, I2C or SPI interfaces.

Many are available as "backpack" or "piggy back" modules which are detachable.

A quick search on eBay will provide some examples:

Serial GLCD Search

Graphic LCD Serial Backpack

There are several Open Source projects concerning this topic as well:

Graphic LCD Serial Backpack

SerialGLCD

The Atmel AVR is fine for monochrome GLCDs, however if you are considering color GLCDs, especially larger displays, ARMs with embedded GLCD display drivers could be better choice.


BigDog