piclist 2001\09\24\124434a >
Thread: High speed sampling --> data storage
face BY : Mike Hardwick email (remove spam text)


I suggest a FIFO memory, e.g. Cypress CY7C462/472 or similar. Commodity
FIFOs are 9 bits wide, so, if you're handy with logic design, you might
consider storing two samples per data word.

Also, I would try to use a commodity ADC before making my own. I think
there are inexpensive and fast 6~8 bit ADCs out there. You can just discard
the unwanted LSBs...

Mike Hardwick
Decade Engineering

>I have run across the problem that I need to do some high speed sampling.
High speed I mean in terms of the PIC.  Running my 876 at max speed of
20MHz, I have not too much time to do things if I want to sample at 500Khz.
And an analog signal at that.  The good part is, I only need low analog
resolutions (maybe 4-bits) so I was going to build a flash ADC from
discretes; 4 bit parallel ouput faster than I can handle.
>But I have to read continuously 128x128 pixels, store it in memory, and
THEN transmit it via very slow serial to a PC (wireless!).
>Now my PIC has 368 bytes of RAM - slight conflict of interest here.
>So I was considering a 16K SRAM (128x128 = 16K).  Does anyone have any
suggestions?? Would this be easy enough to implement? Ie connect my 4bit
adc on port A, read the whole thing and write it parallel via port B to an
SRAM.. that should take less than my 5 allowed instructions =)  I hope!!
unless the SRAM is really complicated.. but I hope not..  I only really
know of SRAM and DRAM, but I know that DRAM will not do the trick =) No
chance to refresh anything here!

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