BRT Community

General Category => Discussion - EVE => Topic started by: FlorianG on April 23, 2024, 02:05:43 AM

Title: Long text on BT 815
Post by: FlorianG on April 23, 2024, 02:05:43 AM

Hi,

do you know if it is possible to display long texts with the BT 815 chip?  I use the Gameduino 3x Dazzler so it is equipped with 8 mega of external RAM.  if I display too much text it crashes because I suppose I am saturating the list of instructions.  List which is too small and remains a big limitation on these chips. 

Ps. my CPU is at teensy 4.0

Title: Re: Long text on BT 815
Post by: BRT Community on April 23, 2024, 08:53:00 AM

Hi,

Could you advise what lengths of strings you were needing to use?

Best Regards, BRT Community

Title: Re: Long text on BT 815
Post by: FlorianG on April 23, 2024, 02:50:58 PM

Thank you for your reply. 
It can be long text of more than 2000 characters

Title: Re: Long text on BT 815
Post by: BRT Community on April 24, 2024, 10:21:58 AM

Hi,

In addition to a few instructions for the actual setup of the font bitmap properties, each character will require at least a Vertex command.

For characters which are beyond the reach of VERTEX2II (e.g. more than 511) there is also a CELL() instruction since EVE needs to use VERTEX2F and that needs a preceding command to set which cell/character.

Therefore, you should budget at least 4 bytes per character and 8 bytes in some cases.

if the text is fixed, you may be able to write it to a bitmap or display it and take a snapshot after start-up and that would save some DL space by displaying the sentence as a bitmap.

Best Regards, BRT Community

Title: Re: Long text on BT 815
Post by: FlorianG on April 24, 2024, 04:44:13 PM

Thank you for your response but I can't.  the text is dynamic.
we can't use the 8m of external ram?

Title: Re: Long text on BT 815
Post by: FlorianG on April 25, 2024, 02:11:05 AM

Another solution that I am considering is to generate an image directly via the CPU with the generated text and then send it to the GPU and display it.
But currently I have a problem with my graphics library because I cannot send uncompressed images via it.
If I send the data to the bt815 memory with uncompressed data it systematically crashes and I can't figure out why. 

I use the Gameduino 3 Dazler library. 

With compressed data it works but I don't know how to compress them directly via the CPU of the teensy 4. So I always have to go through a PC to compress the images and send them to the Teensy which will send it to the graphics chip.  but this prevents me from generating images directly at the heart of teensy