serial memory; help select for serial A/D, D/A

Electronics hacker.

Trying to design and build a very cheap "digital audio recorder". I've located some cheap a/d d/a's with serial memory interfaces from Microchip. I'd like some suggestions as to memory section. I've never used and not familiar with serial ported memory. I'll take care of signal interfacing but, wouldn't it be nice to have something that just "dropped" (or cooperated) into place.

The circuit will record audio until instructed to playback. Then it'll just playback the last n seconds forever.

Thank you.

Reply to
ronaldpeters58_junk
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Lets take some timing into consideration.

At 8 kHz, that's a sample every 125 usec.

So a memory that can write a sample every 120usec would work.

Or a block of data written to a block device.

The block size would determine how many samples you would need to read, then write those samples to the block device.

Add a few more numbers to this and you'll have your design.

You will also have the requirements for the processor you will need.

good luck.

donald

Reply to
donald

Here are the specs - 2 channels, 10K,. 50us and 30 seconds of data...

30- MBs? They even make it that large? But what I'm looking for is a memory part number or mfgr type that would work well. What's the 2n2907 of the memory world? What would interface well with these serial a/d d/a's. Is there a standard serial memory part everyone uses? What about a serial memory with a separate input and output. that just clocked to the next location? Do they make one? I know they used to make 'paged' chips that clocked out a "page". No addressing, just round and round. And no processor, a sequencer. Thanks Donald. You've been helpful. Happy new year too.
Reply to
ronaldpeters58_junk

Oops... should be 300 K?

Reply to
ronaldpeters58_junk

Hmmm,

OK, let me understand what you are asking.

----- ----- | | | | | a/d |----/#/---| mem | | d/a | | | ----- -----

So you want to connect the a/d - d/a to the memory directly ??

I don't think this will work, I don't know of any a/d-d/a or mem that can act as a master.

These devices are slaves to some master device.

Use a PIC. ( ok thats out of the way )

You will need to program some sort of device to go in the middle.

There are all sort of devices, PIC, AVR, MSP430, Motorola HS8, as well as programmable logic devices.

These are just a start.

Let me know what you have in mind.

donald

Reply to
donald

Oh yea, is this a one off project or will you need many of these ?

donald

Reply to
donald

Hi, You might want to look at this article first.

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You should be able to adapt this easily to your requirements. Dan

Reply to
Daniel A. Thomas

how about using a chipcorder?

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alan nishioka snipped-for-privacy@nishioka.com

Reply to
Alan Nishioka

Thank you all for your help.

I want to build a dozen. They are gifts... for Christmas... last Christmas. :-)

For control logic I was hoping to find a sequencer and skip any uP like the PIC (which I don't know how to program and wonder if they could supply fast enough control of the recording loop). I used to program PALs a lot and remember there were devices I called sequencers. They had programmable memory that was just clocked out, glitch free. A few inputs could select banks of preprogrammed signal sequences.

IN-->[a/d]-->[mem]-->[d/a]--->OUT ^ ^ ^ | | | [[[ sequencer ]]]

As to the chip recorder - a fidelity issue. I would like 10khz bandwidth and 30 to 60 seconds record time.

Dan, Rread

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. Hummmm. I'm rethinking my plans.

(It would be nice to find a cheap schmatic capture program that I could use to post ideas.)

Reply to
ronaldpeters58_junk

For serial memory , I use Atmel serial data flash (SPI) in all my products. Available from 1 m/bits to 64 M/bits in 8 pin soic.

Reply to
TT_Man

Well, this will not be done without some sort of logic. The interface and timing of the sequencer will need to be designed. The a/d-d/a devices you have already picked out will need to be evaluated.

So, what parts have you picked out ??

donald

PS: Maybe its time to learn how to program a PIC (or AVR or MSP or ....)

Reply to
donald

Well... maybe it is. Just a quick question. Could a PIC provide, say, 8 digial io ports and be able to update these in less than 10us? How much would that PIC cost. (There seem to be more PIC versions than stars in the sky) They have a developement board for

Reply to
ronaldpeters58_junk

8 digital io bits ??

10usec ?? I don't understand what this means.

Ok, there are lots of PIC boards out there. I use these from time to time:

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First is to count the number of io bits.

The a/d - d/a parts have x number of io bits to operate, which I still do not know which one you are looking at.

The memory device has y io bits to operate. Which has not be chosen yet.

So, how many io bits are required ??? Not a clue, until you make some decisions.

Isn't design fun.

doanld

Reply to
donald

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