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Subject: SV: [Simmons Drums] Re: Q: SDS7 4 e-prom analog/digital card

From: "Hans" <hr.public@...>
Date: 2017-01-27

Thanks for you reply Ewan

 

Good question. That’s what I’m eager to test. According to what I read on the net ATmega boards generally can handle SD at 600kB/s, and most speed troubles people seems to get into are related to write operation.

 

I know for a fact it is not fast enough to emulate an EPROM at 44.1kHz with Arduino library. But my idea is simply to stream 8-bit serial data from SD card to one of the 8-bit parallel ports on the ATmega, clocked from the voice card and speed optimized like I’ve tested here http://snw.lonningdal.no/pg800c.php#code-speed

 

If it’s not fast enough, or unstable I might try to cash to one of these http://www.microchip.com/wwwproducts/en/23LC1024

 

This library are capable of 32khz WAV playback with real-time digital volume manipulation https://github.com/TMRh20/TMRpcm

 

Yes an EPROM emulator is simple, but as you say parts counts are what stopped me. Although a solution like that would be absolutely perfect for anyone designing samples for 8 bit playback. One can process and tweak to sound good on the computer. But after it’s burned and placed inside the host its sound meh. A tool to fast and easy transfer sounds to host for testing is worth something.

 

http://snw.lonningdal.no/sds7eprom.php

 

--h

 

Fra: Simmons_Drums@yahoogroups.com [mailto:Simmons_Drums@yahoogroups.com]
Sendt: 27. januar 2017 08:12
Til: Simmons_Drums@yahoogroups.com
Emne: Re: [Simmons Drums] Re: Q: SDS7 4 e-prom analog/digital card

 

 

Is an atmega328 actualy fast enough to do this directly on the I/o pins?

 

I suspect that reading from an SD card takes a loooong time on arduino.

 

I was looking Into how EPROM emulators work, and what I found was that most of them are just a ram chip that gets data loaded into it from a host computer. This frees you from the timing problems at the cost of increasing your part count..

 

Ewan

 

 

 

On Jan 25, 2017 20:02, "hr.public@... [Simmons_Drums]" <Simmons_Drums@yahoogroups.com> wrote:

 

I just had a eureka moment.

 

Preparing notes for the EPROM project I had a look at the schematics and then it hit me.

Practical problem with EPROM emulation are the 2-byte wide parallel interface needed.

What if we skip that side of the memory control and let the clock on the voice card simply control a modern serial EEPROM, or better - a (micro)SD memory card?

 

Write up and notes on its way, updated frequently so for those interested please refresh. And as always, corrections and direction are welcome.

http://snw.lonningdal.no/sds7eprom.php#sd

 

--hans