Find you’re running out of memory and paying for more expensive chips just to plug this feature gap? Many of the upper offering of chips have the option of adding SRAM thanks to an on-chip hardware feature, but if you don’t have that this 512k SRAM add-on board can be used with any chip that has 13 extra I/O pins available.
That use of pins may sound crippling if you usually use low pin count chips. But thanks to a write protected state option with the memory chips, nine of those thirteen pins can serve a dual use when not reading or writing from the memory. Speaking of, the address scheme is designed to access the memory in 32-bit blocks but individual bytes are accessible too if need be. [Wardy] has been testing his design using a Propeller chip running at 75 MHz so we know it’s built for speed, but he also mentions there’s no minimum clock speed for the board to function either. He used the Open Hardware guidelines when sharing his work, and if you want one for yourself you could always give the DorkBot PDX service he used for the prototypes to get your own boards too.
[via Dangerous Prototypes]
i could blink so many more LEDs if i had one of these…
Thanks for mentioning this HackADay. I appreciate the help 🙂
This SRAM board has actually been tested at 80MHz, but more meaningfully that equates to 20MIPS – for those hackers using other types of microcontroller to compare with.
If I get enough interest in this product I might try manufacturing a small batch for people to buy.
If you are interested in buying one, please leave a comment on my blogspot site (wardyprojects.blogspot.com) and I’ll try to organise a production run.
I’m working on a Developer’s Notes document as we speak, that will help to guide your decision to buy it. The doc will be available in a day or two.
Cheers!
A Microchip 32Kbyte SPI SRAM is my choice when I don’t quite need as much more. 3 pins and the SPI is easy to do either with onchip SPI hardware that most microcontrollers have or just bit-bang.
Beyond that I can use an SD card and go up to 32G.
Together, the 32k SPI SRAM was my fix for faster baud rates on SparkFun’s Openlog – add a 32k buffer and you can wait for the SD card to finish its housekeeping which can take 250mS.
Open bench logic analyser could use one of these on its 3.3v tolerant wing.
Why not just reuse one of the SRAM boards from Pentium era? The one you put in COAST socket (COAST = cache on a stick)
http://en.wikipedia.org/wiki/Cache_on_a_stick
Because they’re weird, rare and hard to come buy?
just want to know ..can I use HY62KF08401C for this extension board? Or, other 512Kx8 SRAM in HY62KF08xxx series?
and, can I use 2 512Kx2 to build a 1M board?
what is the limit of the memory size?
thanks!
Later on today I’ll be making the design available in PDF format (and maybe DXF if possible). Your best course of action regarding that question is to have a look at the schematic and see if it’s pin-compatible.