[Community] Custom display for GTA04

H. Nikolaus Schaller hns at goldelico.com
Tue Oct 27 07:58:40 CET 2015


Am 26.10.2015 um 20:57 schrieb wonderphone at posteo.de:

> Hi Nikolaus,
> What would it take if someone wanted to use a GTA04 replacement board not with a GTA02 case and display but with a different display?

Yes, it is possible. For example the Letux 3704 and Letux 7004 devices use a GTA04 mainboard with different display.

What it needs:
* connector
	- the GTA04 custom board would have two board to board connectors
	- or you can use a 39 pin "jumper cable"
* interface PCB
	- using matching connectors
	- may need level shifter (GTA04 output signals are 1.8V logic levels and some panels need 3.3V)
	- (different) backlight dc/dc converter
	- connection for touch screen
	- depending on the panel type: LVDS or MIPI converter

> The design and the 3D printing of the case might not be that difficult but what would need to be done to attach for example the display of an old (sp)iPhone?

Well, AFAIK the iPhone displays use DSI (MIPI Display Serial Interface) but the GTA02/04 panel is 24 bit RGB parallel. So you need a data and signal converter chip. Toshiba makes some but these are difficult to get and understand and program.

> Would I need another driver or just make some adjustments in the existing one? Would it be possible to connect it at all? Do standards exist in display connectors or are they all proprietary?

You need a different driver. Although there are informal (e.g. RGB-TTL) and formal standards (e.g. MIPI-DSI) they only define a framework and each panel is still different and needs a different control sequence.

So in summary: yes, it is possible and has been done. But you should search for a matching panel instead of choosing one and trying to interface it.
http://www.panelook.com may help.

> Thanks for you insights,
> Oliver


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