topic Re: Can LPC1769 drive LCD parallel output via DMA? in LPC Microcontrollers

Can LPC1769 drive LCD parallel output via DMA?

lpcware — Wed, 15 Jun 2016 17:30:11 GMT

Content originally posted in LPCWare by kiantek on Mon Sep 30 05:34:13 MST 2013
Hi, can LPC1769 drive a LCD similar to LPC1788? Can we use the GPDMA transfer data from memory to GPIO for parallel output?

Sorry guys, I'm confused with the LPC1788 LCD controller. Except being additional DMA channel from GPDMA, is there any difference between the dedicated DMA found in LPC1788 LCD controller and GPDMA found in LPC1769?

Thank you.

KT

Re: Can LPC1769 drive LCD parallel output via DMA?

lpcware — Wed, 15 Jun 2016 17:30:12 GMT

Content originally posted in LPCWare by mc on Mon Sep 30 09:28:00 MST 2013
Hi KT,
LPC1788 has a graphic LCD controller which converts pixel coded data into desired format for example 5:6:5, 5:5:5,6:6:6 etc. It also generates timings (for example Vsync,HSync etc.) to derive various
Single and dual panel monochrome and color LCDs. Examples are STN and TFTs.
LCD controller has its own dedicated DMA controller which can pull data from any memory(Flash/SDRAM/SRAM), and which can be converted to the required format ( You can program it)
by LCD controller. To keep up to speed LCD controller has its own FIFO.

In summary LPC1788 can directly drive LCD panels. In LPC1769 you will have to generate timing as well as need to convert pixel coded data into the required format. GPDMA can be used to transfer data, however format conversion will take CPU cycle.

Hope it helps
MC

Re: Can LPC1769 drive LCD parallel output via DMA?

lpcware — Wed, 15 Jun 2016 17:30:12 GMT

Content originally posted in LPCWare by kiantek on Thu Oct 10 07:06:55 MST 2013
Thank you MC. I got a better understanding after reading your explanation. The pixel conversion is indeed the differentiating points between LPC1769 and LPC1788.

Sorry for the late response. I was trying LPC1769 with Embedded Artists 3.2" TFT LCD and I thought it would be better if I could understand more options before I reply. FYI, instead of parallel interface, I tried 4-wire SPI communication to update the 320x240 screen. But it take 0.6 sec to update the screen, which is very slow.

I will get a LPC1788 dev. board and try out the LCD controller with parallel interface. Thanks for the great help!

Cheers,

KT