On Fri, 23 Oct 2009 08:33:59 -0400, you wrote:

>Microchip doesn't yet have an image sensor interface.  Atmel has a few
>parts, but they all require external memory, and are in the $10-$25
>range, rather than $5 - $10.
>
>What other chips have image sensor interfaces?  (YUV 8, RGB 8/10,
>parallel cmos image sensor)
>
>Is there a chip with onboard flash and ram (32k or more of each,
>ideally, but I can deal with lower ram and flash as long as I don't
>have to buy external memory)?

I looked at this in detail a while ago.
External memory is pretty much inevitable due to the amount of data you need to store. 
If you look at SRAM pricing you will generally find that it is a lot cheaper than the cost adder of
a micro with large on-board RAM. For image sensing you don't necessarily need a true external bus. 

I started off using a LPC2136 ARM, and getting pixels in via FIQs. I could get about 4Mpixels/sec ut
the limit was the 32K RAM available. Looking further I figured a LPC2131 with external 1mbit SRAM
worked out cheaper and gave a lot more available  RAM.

A micro + CPLD+SRAM is probably going to be the cheapest option overall - the CPLD just handles
high-speed timing and address generation, and can probably be a sub $1 part in the 64/72 macrocell
range, e.g. Xilinx XC95 series. You may even be able to do it as just a CPLD+SRAM depending on how
much help you can get from a host micro.

If you want to store more than a few frames, the cheapest SDRAM is comparable in cost to the
cheapest SRAM, but with approx 64x the capacity, however the control is somewhat more complex and
you will probably be looking at low-end FPGA instead of CPLD. With SDRAM you often need a small SRAM
buffer to smooth out the data throughput to SDRAM - FPGAs, even cheap ones like the Lattice EC1 have
sufficient RAM to handle this easily.



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