LPC1788 with 800 X 480 Touch Display

[lpcware]

Content originally posted in LPCWare by ridake on Sat Jun 04 05:42:20 MST 2016
              I want to use 800 x 480 Newhaven Touch Display with LPC1788. But i have one doubt about frame buffer of LPC1788, with 800x480 pixels color depth of 24 bit it requires 1.152MB of frame buffer memory, but controller has only 96KB of SRAM. So for this requirement should i use External SDRAM? or Can i able to manage with internal memory? actually i want to use LPC1788 144 pin package which does not has the External Memory Controller.

[lpcware]

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[lpcware]

Content originally posted in LPCWare by rons on Sat Jun 11 09:25:44 MST 2016
If you already have the 144 pin part you can dedicate GPIO pins to access the external memory frame buffer. I did something like this with a 16bit 8051 running at 30MHz and a 320x240 LCD. The 8051 continuously cycles through the memory buffer and has a little bandwidth left to run a guitar chord/scale training program. The picture just shows my first test program.


In other words, no LCD controller. Just raw cpu accesses in a interrupt routine. The frame rate is 55Hz.

[lpcware]

Content originally posted in LPCWare by MikeSimmonds on Wed Jun 08 03:59:01 MST 2016
I don't play LCD, so I have no idea as to bandwidth requirements.

The 8-bit data bus width will apply to ALL external memory (on the 144 pin device) whether SRAM, SDRAM or whatever.
I.e any access to external ram will require one bus cycle per 8-bit byte.
This will obviously limit throughput as compared to a 16-bit or 32-bit data bus.
Note that you can still read/write e.g. 32-bit words in code -- the access will be split into 4 x 8-bit accesses by the hardware.

It would appear (but don't rely on me -- I am not a doctor/lawyer/hardware engineer!) that the specified configuration
MAY have problems keeping up with LCD refreshes.

But maybe you application is displaying 'static' screens in a menu like way; in which case the limited bandwidth* MAY
be acceptable.

*I.e. slow update speed.

Are you locked into a design or could you upgrade to the LQFP 208 part?

Cheers, Mike.

[lpcware]

Content originally posted in LPCWare by ridake on Tue Jun 07 22:46:05 MST 2016
hi mike,
Thanks for the reply,

Is that 8 bit data bus sufficient to interface as LCD data buffer for 800x480 pixel with 24bit color depth display? or i have to use SDRAM interface with 16 or 32 bit data bus for display buffer?? and that 8 bit data bus supports only static SRAM only, is that okay??

[lpcware]

Content originally posted in LPCWare by MikeSimmonds on Mon Jun 06 07:38:16 MST 2016
The LPC1788 144 pin package does have an external memory interface, but it is limited to an 8 bit data bus.
See the User Manual.

Cheers, Mike.