Other Parts Discussed in Thread: TM4C129XNCZAD
Following up on CS1142770 created some week ago or so.
Our project is to use the TM4C129Xnczad in our V2401 project (TM4C1299ncad is installed in our board) that is to replace a V2400 project that used the NXP K70 that has been unavailable for a long time and not seen in the near future. After evaluation I decided to go for the TM4C129Xncad even it isn't a "brand new" one as I had a very good experience with TI from the 1980's with the TMS9980 and TMS9995. Now to the problem: The V2401 uses the 24bit RGB interface, the first 18 lines controlled and I place the RGB data in 6-6-6 to the framebuffer.
I have been trying to use the Tiva TM4C1299 with a VGA LCD display but stumbled on quite a dilemma.
I can't use the SDRAM I have on the EPI bus as if the ram in on address 0x60000000 then I get a lot of flicker while updating display and if I have it on address 0x10000000 I can't run code from it as intended. This is due to underflow (have confirmed that) and finally it runs into a halt of the LCD controller (rest of the devices are working, like UART so the V2401 isn't frozen).
Reading the documents on the Tiva series the limited information on the use of palette gave me the idea to use a 16 color palette using indexes in framebuffer that would hold two pixels per byte. Isn't that possible?
Internal uC ram is 256Kbyte, LCD is 640x480 pixels
Question is therefore mainly about the NIBBLE mode in the LCD controller.
The RASTER_NIBBLE_MODE_ENABLED, does that enable me to use the framebuffer as nibble, e.g. 4 bits index to palette so two pixels are per byte? that would then enable me to use the internal SRAM as the framebuffer would need only 153600 bytes + palette of 16*2bytes. It is quite unclear if it is possible or not
I am willing to go to 16bit RGB or even 12bit using 16color palette if that solves the issue and then change my PCB or make a different LCD cable.
p.s.: I did send an unfinished source to the customer support chat: - have been trying a lot of things
