RAM RAM RAM how much do you need?

mctrivia

Well there are lots of people making RAM modules in different ways. I still have designs for a bigger RAM module with built in HDMI output but I wanted something simpler and cheaper to offer in the mean time.

Ale gave me a great idea PSRAM. Cheaper then SRAM but as convenient to use other then the form factor.

I have designed a stackable 8M Word RAM module. These modules can be stacked up 8 high and act as a single 128M Word RAM Module. The tallest header I have found though is 95066-230HLF which would only allow for stacking 4 high so 2 stacks would be needed for full RAM area if you need that much RAM.

Random Access Time is 70ns however the modules support a 133MHz burst mode for sequential read/writes.

This is not a direct replacement of MITs 16MB RAM Module for $900 but each module does hold the same amount of RAM you just need to provide your own glue logic which is not expensive.

Each RAM Module would cost $39.99. I need to sell at least 25 and was wondering if there is enough interest.

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Ale

Something mctrivia did not mention is that PSRAM supports burst mode with automatic address increment, so you only have to supply the address once and the stream the data back to the prop (like SDRAM), but you do not worry about refresh at all.. That can be done in chunks of 2, 4 8 or full page (words of 18 bits).

It needs a bit of glue logic. I'm working on a FPGA-geladen board that will support this module too. If there is interest, mctrivia could provide boards for that.

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Oldbitcollector (Jeff)

Please don't take this the wrong way.. (I don't want to kick sand on anyone's project)

It seems that the actual RAM size is significantly increasing the price.

We're all used to dealing with 32K limitation. Any xMB increase would be a huge upgrade,
but honestly I'd be happy with an additional 32K-256K solution, adapted as "standard"

Is this even possible? It seems that if it were the price would be considerably more in line
with what hobbyist budgets (and their spouses) would more easily allow. [noparse]:)[/noparse]

A smaller $10-$19 solution would be reachable by even our youngest members.
The beauty of the SD solution is that it is high storage at little cost. Can our memory solution match it?

OBC

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Post Edited (Oldbitcollector) : 11/3/2009 6:08:23 PM GMT

mctrivia

I chose 8M word because it is a large amount of ram that I can provide cheap.

If you only need 256k don't use all the io lines. I could not economically make a board much cheaper even if I cut the size down a lot.

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mctrivia

Bigest place I can save money is if no one wants to be able to stack more then 1 then I could cut out the connectors and save $5

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Rsadeika

Your, cheaper than MIT sales pitch, is not not going to get you very far. If you are looking for a market, think about making some 'shields' for the Propeller Platform Module (PPM). Lets say for about $20, you make a 'shield', fully assembled, with drivers, that has an SD socket, and maybe 512-1024KB of ram. If it is plug&play, than even beginners would not have to much trouble getting involved with the PPM as their first choice.

Bill Henning

Hi OBC,

32K is easy and cheap - just get a Microchip 23K256 SPI SRAM chip [noparse]:)[/noparse] It's a nice easy 8 pin dip, and with a modified version of Kurenko's counter based SD card code should be able to do reads/writes at 20Mbps.

The problem with any memory add-on (or any board as a matter of fact, especially if designed to sell for even a minimal profit) is the overhead costs.

Rough example:

ExpressPCB = $55 or so for 3 boards, making it $18.33 per board. To get cheaper boards, you have to make a lot more of them, but if you know where to go, you can get small boards, qty 100 or so, for $3-$5 each. Less in larger quantities.

Assume you have to do at leat one prototype run. Can't use ExpressPCB - they don't take gerbers. Assume $80-$100 for the initial prototype run.

To get the memory chips at a decent price, you have to buy them in quantity. let's say you buy 100x 512kx8 chips, for just over $3 each.

Now you need at the very least a decoupling capacitor, and some pins... plus some latches if you don't want to use all the prop pins. But let's use the prop pins. say $1 in qty 100 for the caps and the pins/headers.

What do we have so far?

$100 (proto PCB)
$300-$500 (production PCB's)
$350 (100 memory chips)
$100 (cap and pins)
$150 (approx minimum shipping for above)

---

$1000-$1200 for 100 saleable boards.

Now let's not forget about all the time spent laying out the board, testing it, chasing down best prices, ordering parts. Or taxes, duties, etc.

Let's not forget having to fork out $1000-$1200 up front before selling a single board.

But for this simple calculation, let's forget labor costs.

Now if you want to sell to distribution, they want 40%-50% off MSRP, so you have to double the sale price just to break even.

So without labor costs counted, and with no profit, you are looking at a for sale price of $20-$24 per board, assuming you sell all boards.

Now if you actually want to be paid even minimally for your time, and want to make even a little profit, you have to double that again.

Now we are at about $40 - $56 for an extremely dumb, simple, 512KB board as a kit, without even a socket for the memory chip, that uses almost all of a propeller's pins (or at least half that if sold directly... but then we have PayPal fees)

And you have zero certainty of selling all the boards.

Using a smaller memory chip, say a 128Kx8, would save you about $1-$2 on parts costs, say $4-$8 on kit price.

Oldbitcollector said...
Please don't take this the wrong way.. (I don't want to kick sand on anyone's project)

It seems that the actual RAM size is significantly increasing the price.

We're all used to dealing with 32K limitation. Any xMB increase would be a huge upgrade,
but honestly I'd be happy with an additional 32K-256K solution, adapted as "standard"

Is this even possible? It seems that if it were the price would be considerably more in line
with what hobbyist budgets (and their spouses) would more easily allow. [noparse]:)[/noparse]

A smaller $10-$19 solution would be reachable by even our youngest members.
The beauty of the SD solution is that it is high storage at little cost. Can our memory solution match it?

OBC

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www.mikronauts.com Please use mikronauts _at_ gmail _dot_ com to contact me off-forum, my PM is almost totally full
Morpheusdual Prop SBC w/ 512KB kit $119.95, Mem+2MB memory IO board kit $89.95, both kits $189.95
Propteus and Proteus for Propeller prototyping 6.250MHz custom Crystals run Propellers at 100MHz
Las - Large model assembler for the Propeller Largos - a feature full nano operating system for the Propeller

Post Edited (Bill Henning) : 11/3/2009 7:04:14 PM GMT

David B

I could use several megs of RAM for storing a long burst of ADC data, as long as it could be written to at about 5 megasamples per second. The auto-addressing looks helpful for that.

I'd want to see details on how to operate it - address initialization, control pins needed, the time requirements of the various states, and if there are any limitations, such as if the RAM refreshes itself, do you have to halt updates periodically to allow the internal refreshing to take place, and how often and for how long, that sort of thing.

For my current project, I'd want at least a meg, but wouldn't need any more than a few megs, so I wouldn't care about stacking.

I've already used a 512K static RAM chip with hand-wired counters to auto-increment the address for a similar project, and that chip cost something like $17 a few years ago. So I could see paying that price for your board if it would work in my project.

mctrivia

Refresh is done automatically to mimic sram.

I will upload the chips data sheet when I get home in a few hours.

133mhz is fastest transfer rate so 5mhz should not be a problem.

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mctrivia

here is the datasheet for the RAM.

Some notes:
*CS is reversed in the module so it is active high instead of active low.
*Address lines 23-25 can be used in place of CS if you need to save pins.

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24 bit LCD Breakout Board coming soon. $21.99 has backlight driver and touch sensitive decoder.

Andrey Demenev

Bill Henning said...
It's a nice easy 8 pin dip, and with a modified version of Kurenko's counter based SD card code should be able to do reads/writes at 20Mbps.

I have seen this mysterious Kurenko's code mentioned several times, but failed to find it. Could someone please point where it can be found?

Bill Henning

I believe it is embedded in the latest fsrw code... http://forums.parallax.com/forums/default.aspx?f=25&p=8&m=368563

Andrey Demenev said...

Bill Henning said...
It's a nice easy 8 pin dip, and with a modified version of Kurenko's counter based SD card code should be able to do reads/writes at 20Mbps.

I have seen this mysterious Kurenko's code mentioned several times, but failed to find it. Could someone please point where it can be found?

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Morpheusdual Prop SBC w/ 512KB kit $119.95, Mem+2MB memory IO board kit $89.95, both kits $189.95
Propteus and Proteus for Propeller prototyping 6.250MHz custom Crystals run Propellers at 100MHz
Las - Large model assembler for the Propeller Largos - a feature full nano operating system for the Propeller

Ale

mctrivia:

I was wondering if your board could have 2 mm connectors instead of 2.54 mm

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mctrivia

yes if I could find a good male counter parts for the 2mm headers.

I would prefer to use 2mm because of lower profile slightly cheaper headers available and making my board 8mm shorter but the lack of easily usable male headers is a problem.

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Post Edited (mctrivia) : 11/4/2009 4:27:53 PM GMT

mctrivia

I have ruffed out a design for a morpheus module that would utilize memory area $800000-$FFFFFF and give you up to 16 pages of 8MB RAM area. Need exact module dimensions and pin location to finish.

Because there is no clock pin available on header burst mode can not be utilized.
The read/write time is 70ns for true random which is slightly slower then the bus can handle but if you only change addresses A0-A3 the read/write time is only 20ns so with optimization in code it can run almost full speed.

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Ale

Do you have a new pinout ?

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mctrivia

no pinout is the same. It is a result of the pin layout of the bga memory used. the morpheus board is another board that adapts the morphbus to 2 stacks for use with these modules. it also has a few active components to decode the io port and allow for paging the memory and to generate the needed 1.8V power rail.

I mention it because I am trying to see if there is enough interest to sell at least 25 modules before I invest the $1000 into a product run.

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lonesock

Andrey Demenev said...

Bill Henning said...
It's a nice easy 8 pin dip, and with a modified version of Kurenko's counter based SD card code should be able to do reads/writes at 20Mbps.

I have seen this mysterious Kurenko's code mentioned several times, but failed to find it. Could someone please point where it can be found?

This is possibly because:
1 - The correct spelling seems to be "kuroneko"
2 - kuroneko didn't do the code in FSRW
3 - kuroneko did something earlier and similar (not targeting SPI, though) here: http://forums.parallax.com/showthread.php?p=784536

[noparse][[/noparse]8^)

Jonathan

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lonesock
Piranha are people too.

Oldbitcollector (Jeff)

Bill Henning said...


What do we have so far?

$100 (proto PCB)
$300-$500 (production PCB's)
$350 (100 memory chips)
$100 (cap and pins)
$150 (approx minimum shipping for above)

---

$1000-$1200 for 100 saleable boards.

Now let's not forget about all the time spent laying out the board, testing it, chasing down best prices, ordering parts. Or taxes, duties, etc.

I appreciate this, and hope I didn't come off as presenting mctrivia as ripping folks off.. (not my intent!!)
I just wish we had a solution as elegant and cheap as the SD storage solution. Almost anyone can
assemble an SD interface under $5.00, and a "commercial" product can be purchased around $20.00.

It might make an interesting poll to see what the typical hobbyist budget is for regular purchases.
(For me, I can spend $20-$30 here or there without spousal discussion. [noparse]:)[/noparse] There's no chance
of my purchasing one of those $4,000 gas powered Parallax bots any time soon. [noparse]:)[/noparse]

OBC

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mctrivia

I agree it would be nice to make modules for cheaper. But i do need some profit so I can make more modules and not lose to much. I do this for the fun of it, to help the propeller community, and to build a portfolio of commercial products. All of my products to date are priced extremely cheaply and so far I have not made any profit on any.

I am currently $200 short of breaking even for my breakout board for Raymans LCD
My propmodules I am several hundread short of breaking even.

As for your question I get $125/month allowance. Everything else needs to be talked about and agreed on.

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mikediv

Oldbitcollector Wow you just wrote what I have been thinking every time I see a thread for Ram ,, And of course no knock to MC he has awesome stuff and has always shared his knowledge Thank you sir
but Oldbit is spot on about the hobby thing it would be awesome if I could (and have tried) to just wire up 256K or even a 1M I bought a few SPI flash rams from sparkfun actually one is a,, AT45DB161D,,16Meg with a carrier board for 6 dollars but I do not posses the software skills to get it to work. I fully understand MC the need to be able to make money and I mean no insult but a even a $20 dollar ram kit with software would be such a great upgrade especially for us neewbies my coding skill are so lacking that my code is huge and I always run out of ram
mctrivia is there anyway a a quantity purchase from you would make it economically visible for you to build say an"AT45DB161D" kit that would work with the prop chips????? Please understand I claim no special knowledge of how to do this
just asking out loud.

Bill Henning

Hi,

You have mail with dimensions [noparse]:)[/noparse]

If you map it as 4MB, I can generate a clock on A0, but you will have to "shift right" the address bits by one... ie:

A23=1 is your chipselect
A22 is your A21
A21 is your A20
...
A1 is your A0

A0 is your clock for burst mode

I know, it will use 8MB of address space for 4MB of mapped memory, but we can have 32 4MB pages with burst mode...

Best,

Bill

mctrivia said...
I have ruffed out a design for a morpheus module that would utilize memory area $800000-$FFFFFF and give you up to 16 pages of 8MB RAM area. Need exact module dimensions and pin location to finish.

Because there is no clock pin available on header burst mode can not be utilized.
The read/write time is 70ns for true random which is slightly slower then the bus can handle but if you only change addresses A0-A3 the read/write time is only 20ns so with optimization in code it can run almost full speed.

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Morpheusdual Prop SBC w/ 512KB kit $119.95, Mem+2MB memory IO board kit $89.95, both kits $189.95
Propteus and Proteus for Propeller prototyping 6.250MHz custom Crystals run Propellers at 100MHz
Las - Large model assembler for the Propeller Largos - a feature full nano operating system for the Propeller

mctrivia

I can use the controller to generate the clk signal from A0 while aintaining the full 8MB space but i figured it would not be much faster then random read if you have to toggle a0 on and off for each byte.

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24 bit LCD Breakout Board coming soon. $21.99 has backlight driver and touch sensitive decoder.

Bill Henning

I am thinking of using a counter to drive A0... I think 32x 4MB pages with burst mode is better than 16x 8M pages without burst mode [noparse]:)[/noparse]

mctrivia said...
I can use the controller to generate the clk signal from A0 while aintaining the full 8MB space but i figured it would not be much faster then random read if you have to toggle a0 on and off for each byte.

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Morpheusdual Prop SBC w/ 512KB kit $119.95, Mem+2MB memory IO board kit $89.95, both kits $189.95
Propteus and Proteus for Propeller prototyping 6.250MHz custom Crystals run Propellers at 100MHz
Las - Large model assembler for the Propeller Largos - a feature full nano operating system for the Propeller

Bill Henning

lonesock:

thanks for the correction!

OBC:

you are welcome - I figured lots of people did not know what was involved in bringing even a cheap PCB to market, so I thought it would help if I showed the process.

mikediv:

a $20 ram kit is not workable. See my response to OBC earlier in the thread.

A bare board without parts is possible, but then you will have to run around sourcing parts, and paying shipping to multiple vendors, paying a lot more overall.

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Morpheusdual Prop SBC w/ 512KB kit $119.95, Mem+2MB memory IO board kit $89.95, both kits $189.95
Propteus and Proteus for Propeller prototyping 6.250MHz custom Crystals run Propellers at 100MHz
Las - Large model assembler for the Propeller Largos - a feature full nano operating system for the Propeller

mctrivia

I can give burst mode either way if you can provide me a fast clock on a pin. I since the address lines are ignored during burst they can be routed to both clock and address. We only need to agree on a standard on what address values trigger the adv, clk, and cre pins.

Can start burst by writing a 1 to bit 4 of io port. Then set start address and then start clocking. After 3 clocks start streaming data.

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24 bit LCD Breakout Board coming soon. $21.99 has backlight driver and touch sensitive decoder.

Bill Henning

Sounds even better!

so the I/O port could be:

BXXXXPPP

where

X=don't care at this time
B=Burst mode
PPP=page address

This would allow for up to 128 pages later - in case there are bigger modules in the future.

How about using A0-A2 for adv/clk/cre during burst mode? ie

A0 = clk
A1 = adv
A2 = cre

mctrivia said...
I can give burst mode either way if you can provide me a fast clock on a pin. I since the address lines are ignored during burst they can be routed to both clock and address. We only need to agree on a standard on what address values trigger the adv, clk, and cre pins.

Can start burst by writing a 1 to bit 4 of io port. Then set start address and then start clocking. After 3 clocks start streaming data.

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Morpheusdual Prop SBC w/ 512KB kit $119.95, Mem+2MB memory IO board kit $89.95, both kits $189.95
Propteus and Proteus for Propeller prototyping 6.250MHz custom Crystals run Propellers at 100MHz
Las - Large model assembler for the Propeller Largos - a feature full nano operating system for the Propeller

mctrivia

BXXXPPPP i think you mean.

yes that should work.

I want to keep to 8MB block because it would let me use the same PCB for both a full blown multipage version and a cheaper single page version.

The single page version would not support burst mode though and have the module directly soldered on.

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24 bit LCD Breakout Board coming soon. $21.99 has backlight driver and touch sensitive decoder.

mikediv

MC understood. MC can I ask just using the part number I listed earlier is it the software portion that takes so much time to develop more so than the hardware portion of the design? Because when I see a part like the one listed 16 Meg SPI I am sure I am overlooking some aspect
it can't really be 16M can it? Does the fact the Prop is 32 bit not significantly lower the actual ram available? I am very un-clear on how this works I have a basic understanding of 8 bit 16 bit 32 bit and so on but how would that relate to a serial ram device?
Thanks guys I just do not understand why it wouldn't be an easy task to interface a chip like this???

Dr_Acula

@mikediv, without wanting to hijack this thread, I've pondered those flash ram chips as well. eg www.futurlec.com/ICFLASH.shtml. First, they are megaBits, not megaBytes. So 16Mb is actually 2 mega Bytes. But they are very cheap ($1.70) and small. On the downside, they are serial, so slower. And they are flash, which means they wear out. SRAM chips on the other hand are parallel (much faster) and never wear out. SRAM has a sweet spot for price at about 512k (kilo Bytes). So 1/4 the size of the atmega chip. The atmega flash chips have a sweet spot at about 32megabits ie 4 megabytes, ie 8x the SRAM capacity). But for twice the price, you can go to SD cards which have gigabyte capacities and are removeable.

The atmega chips are a fallback for me but I very much want to conquer the SD card code as it opens up so many possibilities.

With respect to how much ram, it depends what you do with it. Working code that is being used as part of a program logically would be SRAM. For me, 512k is perfect. But 32k is not nearly enough. But for storage, SD would be the best. An operating system like CP/M (or PropDOS) logically seperates the two tasks - you have programs that you store somewhere, that are written occasionally and read somewhat often, and for that function an SD card is perfect. The speed is not so important when 'loading' a program. But for working memory where you want speed and random access, SRAM is the best. The atmega chips possibly fill a niche somewhere inbetween.

As an aside, I've got all these old PCs lying around from 10 years ago that have 32megabyte and 64 megabyte ram modules in them. They seem to be sram type chips. And they are probably giveaways at computer stores (I've seen people make 'tech jewelry' out of them). I wonder what it would take to interface to those modules? Lots of pins, so possibly some latches, but the modules would be free...

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Post Edited (Dr_Acula) : 11/5/2009 12:39:19 AM GMT

Bill Henning

They are all DRAMs, either FPM, EDO or SDRAM. Think lots of pins, having to do refresh, having to do RAS, CAS and bank selection. The modules are cheap, but at a guess, even a simple adapter (without margin for distribution) would cost around $50, at least $120 with distributor margin. Not including the memory module.

Dr_Acula said...
As an aside, I've got all these old PCs lying around from 10 years ago that have 32megabyte and 64 megabyte ram modules in them. They seem to be sram type chips. And they are probably giveaways at computer stores (I've seen people make 'tech jewelry' out of them). I wonder what it would take to interface to those modules? Lots of pins, so possibly some latches, but the modules would be free...

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
www.mikronauts.com Please use mikronauts _at_ gmail _dot_ com to contact me off-forum, my PM is almost totally full
Morpheusdual Prop SBC w/ 512KB kit $119.95, Mem+2MB memory IO board kit $89.95, both kits $189.95
Propteus and Proteus for Propeller prototyping 6.250MHz custom Crystals run Propellers at 100MHz
Las - Large model assembler for the Propeller Largos - a feature full nano operating system for the Propeller