Before I build it

average joe

Any thoughts on this Memory Board? Designed from SPARE PARTS! *That explains why I have 9 2k sram and an 8k sram. Project also uses 2- 2x20 lcds, 9 leds (8 clocked off the data bus) a 3x4 keypad also on the data bus. I'm not looking for top speed data transfers but more of a large storage space.

Toby Seckshund

You sound like you work along my practices. I scrounge all sorts of stuff "because it is a shame to throw it away". The result is draws full of old junk which is ok for dabbling but can hold you back on doing the task much more simply with one bigger, newer chip that is faster and takes less power. Board layout takes an age too and more bits meens more problems. I know I am complicating my own life but habits of a lifetime ...

kwinn

At one time you could save enough by reusing the old odds and sods in the junk drawer and I used to do so. Then I took a good look at what using those "free" parts cost. In a lot of cases the extra PCB real estate required cost more than I saved, and the additional time and complexity made it several times worse. Why would you use 10 chips plus the glue logic to get 26K of ram when you can get a 512K chip for 5 or 6 dollars. I got over my bad habit and I would urge you to do the same.

Toby Seckshund

With me it's a fine balancing trick. Old stuff is my "old junk" and new stuff is "a complete waste of money", according to HER. Therefore lots of old stuff is camoflage for the new stuff. The trouble is, I start to look at the old stuff and start dreaming of the things I always wanted to do, at the time when it was new stuff. 32Kb rams seem to be a great weakness, the cure for Z80 fever has worn off too!

BADHABIT

I am slowly getting over the phobia of throwing away the older "free" stuff. In a few days you can get free samples of new stuff and you don't have to store for years - you just order it when you need it.

Maxim is great for this, also Linear Technology. I just got 5 different pairs of IC's. It took 7 days, and it was free(at least for me - the postage on the envelopes says 4.95 ).



BH

Post Edited (BADHABIT) : 6/6/2009 7:59:53 PM GMT

kwinn

Well, I must admit I still keep a lot of old stuff. Some of it is for my service business, and some is useful still. I still use 32K rams/eeproms and Z80 cpu chips occasionally for a project when that is all the memory I need. If I needed more than 64K though I would buy new chips of a size that minimizes the chip count. Old habits die hard.

average joe

Well after the advice I am going to back burner this project, just thought I'd share my schematic. I may end up using this later, with some changes of course. Primarily removing the common data bus, or using 373s to connect each chip to the module it controls. Right now I have 5 modules under development

Ok maybe I should give a little more in depth information about the project here.... The plan is to hook it up to my guitar, effects processors, and computer / keyboard.... maybe even my sampler. I have several pieces and tons of ideas. The main part that is built and tested *although it will be receiving major upgrades* is the router. 2 guitar pickups into buffers... a long cable run into the main switching unit. Then off to the respective effects processors... The pickup switch is also sent over the long cable run and hooked up to pins. Also the 8 bit data line and clock for the selector. I am currently using a bs2 for this but plan on working on the proprpm.


The next module will be the Dynamics module. I have several ideas based around a VCA in an Alesis Microlimiter. Using a 0-5v control signal introduced directly to the vca. Any thoughts comments or suggestions?

hinv

Hey Joe,

Have you checked out www.openstomp.com. It is a guitar effects processor built on the propeller. It has 1.5MB of sram on board. He even published the schematic. Check it out!

Doug

average joe

I've looked at it quite a bit and do plan on buying one. It is an incredible design and can't wait to get my hands on one. What I'm working on is more of a controller interface, although there are several modules that process the sound in the analog domain. I love the flexibility of dsp, but that's not where I'm going with this. It all started when I wanted to use 2 different effects processors at the same time. Then came the first 2 button, 2 led ABY switch. Very simple, but it keeps getting more complex as time goes on....

kwinn

Average Joe, after a quick look at your schematic I may have to retract or at least modify what I said. I did not have time to figure out what you are trying to accomplish but if you need a smaller memory with a wide data bus you need multiple chips any way.