using Dynamic RAM with AVR 20 pins
2004-09-27 by alan_probandt
Hello, 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.