On Sat, 27 Feb 2010 17:35:15 -0600, you wrote:

>I know I've probably asked this question before here or elsewhere, but I 
>need a cost effective alternative to the SSD1926 RGB LCD driver.  I'm 
>using it between a PIC24 and a 472x280 resolution LCD that has a 24 bit 
>RGB interface (8 bits per pixel), and the standard hsync, vsync, pixel 
>clock control lines.  In addition to the horrible availability of this 
>part and the high price ($7 is the best I've seen in about 1K 
>quantities, and I'm only looking at using around 250 annually now), it 
>requires that I have a 1.8V supply available, and about a 4MHz crystal.  

You can probably get 4MHZ from a PIC24 compare output - 1.8v regs aren't exactly expensive (e.g.
Microchip MCP1700) as long as you're not after the last drop of efficiency by using a switcher. 

>All this is detracting from my ability to manufacture something at a 
>reasonable price.  Some time ago, it was suggested that I might be able 
>to make my own driver using some kind of programmable logic device.  
>Does anyone either know of a direct alternative to the Solomon Systech 
>part, or where I might start in terms of CPLDs.  I have absolutely no 
>experience with CPLDs, or FPGAs, but I'm curious about the subject and 
>would be interested in doing something if I could get the core parts 
>cheaper and learn something in the process - but only if it's not 
>leading me down a dead end. 

The  minimum hardware would be a CPLD and a SRAM - you could probably offload some of the work, like
sync generation,  onto the PIC's timer/compare/PWM modules to reduce the size of CPLD required. For
some reason there is a big price jump in CPLDs above around 72 macrocells, so anything you can do on
the MCU will help.

A CPLD+SRAM solution would help with availability but I doubt you'd save a lot on cost (although at
low volumes the gap may be bigger) - much of the cost is the silicon area of the SRAM required,
which you have whether it's integrated on the controller or seperate.
Unfortunately, MCUs with integrated TFT-LCD controllers (e.g. ARM LPC247x) also come with a bunch or
stuff you don't need, but still pay for, and even then often need external RAM.

FPGA would be more expensive unless you could also utilise it for other parts of the system. 

I did read recently about an MCU with enough onboard RAM to run its onboard tft controller with no
external RAM - I think it was Renesas .


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