RA8875 TFT Controller - any good?

Go To Last Post
5 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi there,

 

If anyone has used an RA8875 and has any useful feedback (good or bad) that would be much appreciated

 

I know it wont be any good for displaying large bitmap images at speed but I don't need that

 

I plan on using if mainly for displaying text and I need the display to scroll up when the screen is full so any hardware on-board that would make that process simpler would be a bonus 

 

Also anyone here happen to know what the maximum SPI clock speed is for the RA8875 as I plan on using SPI interface

 

Regards

Steve

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Yes,  of course it works.   You can discover the maximum SPI speed when you read the data sheet.

Yes,  it will display text with different fonts and do several graphics primitives by itself.

Yes,  it can render large bitmap images very fast from an SPI Flash chip or from microSD.

 

Even though you might choose to use a slow I2C or SPI interface,   the grunt is done by the RA8875.    e.g. drawing a filled ellipse.

 

Most TFT controllers can do vertical scroll of the whole screen in hardware.   Modern chips like ILI9341 can even scroll a sub-window of the screen.

 

When you use hardware scrolling,  the effect is instant.   However you need to keep track of where you are in software.

 

David.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Also check https://developer.mbed.org/compo...

 

David 

 

<edit> corrected link

Last Edited: Sat. Nov 7, 2015 - 09:18 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

The spec sheet  I had made no mention of the maximum SPI clock speed. I now have tracked down a newer datasheet and it states it as:

 

system clock/3 for write & system clock/6 for read

 

not sure what the system clock frequency would be yet - I assume that would depend on the programmed PLL settings which would be determines by the screen resolution i.e. pixel clock

 

Thanks DAFlippers - that site looks like it could be very useful

 

I am still interested to hear if anyone has actually used an RA8875 and how they rate it relative to other solutions

 

Internet suggests it is riddled with hardware bugs, but that may be early silicon they are referring too

 

Any first hand experience would be a much more accurate picture of the devices true potential than what any crypic datasheet may claim in my book

 

Regards

Steve

 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Yes, I have used a RA8875 but not extensively.

If you are looking at a large intelligent display, there are several boards on the market that have their own microcontroller and just accept high level commands from a "slow" interface.

What do you actually want to do? You can render text very smartly with your AVR and unintelligent hardware. e.g. the scrolling.

David.