I don't know but here is a link
and this one
----- Original Message -----From: alan_probandtSent: Tuesday, September 28, 2004 8:56 AMSubject: [AVR-Chat] using Dynamic RAM with AVR 20 pinsHello,
Does anyone have any experience using simple and cheap dynamic RAM
chips with the 20 or greater pin size AVR?
I'm thinking of an audio digital delay (echo...echo...echo...) that
would use a 64K by 1 or 256K by 1 dynamic RAM chip.
As I understand it, you could put the address lines of the dRAM
chip to the 8-bit portb of the AT2313 and use the port d lines for
RAS\, CAS\, data in\out and Write\. If you read 128 consequitive
addresses in 120 milliSeconds, you refresh the data and won't lose
any.
I think that you could start a 10-bit ADC conversion. Then as each
bit was read from the SPI, store it in a register. Then put the
address row on the port B, strobe RAS\, put address column on port b,
strobe CAS\, read the bit, send the bit received from the ADC. Then
send the stored bit to a SPI DAC. Do it fast enough and you get a
about 300 milliseconds of 10-bit audio delay for about $10.
Is there anything that I'm overlooking? Are there any gotchas that
prevent using dynamic RAM with AVRs?
Maybe I should just by a used guitar stompbox digital delay on eBay
and save myself a lot of designer grief.