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Topic: UM621024C-70LL 128K x 8-bit CMOS Static RAM and Arduino Pro mini (Read 3350 times) previous topic - next topic

metheoneandonly

Hi!

First, I apologize if this topic already exist, although I didn't found it.
Can this SRAM http://www.ebay.com/itm/UM621024C-70LL-128K-x-8-bit-CMOS-Static-RAM-DIP-32-UMC-NEW-SRAM-1pcs-/261968047728 be used with Arduino Pro mini?

Thanks in advance!

pito

Any sram can be used with any microcontroller, provided you have enough pins available, or, you use a pin expander. Then you "bitbang" the memory signals thus you can read and write into it.

You cannot expand internal sram of an ordinary arduino atmel chips however.
An example what the people have done in order to connect an 8MB sram to Uno :)
http://forum.arduino.cc/index.php?topic=220918.0

majek

To be correct: you can connect it and use as internal SRAM on bigger AVR chips as Atmega128 or Atmega1280/2560 (used in MEGA boards).
Of course, it's not possible directly in Atmega328 on Pro mini. Even using it in software could be quite difficult as pin count required to connect UM621024 is larger than all Atmega328's I/O pins. But with some external chips it could be possible.

monte_carlo_ecm

You need 8 digital pins for the I/O lines, and 3 for the control lines - one each for Chip Enable, Output Enable, and Read/Write.  That leaves you with only 3 open pins for address lines using an Arduino Pro mini.  So unless you only need 8 bytes of memory or you are up for building a whole lot of extra shifting circuitry, you should get a board with more digital pins!

I'm working with a very similar style SRAM with an Arduino Mega.  My chip is a Dual Port SRAM, but aside from that works on the same old fashion address line approach as the chip you are looking at.  I'm having some trouble with glitches in an automobile application, but outside of the environment issues I'm having, it works great.  You can have a look at how I went about it here:

Occasional error reading from AM2130/IDT7132 Dual Port SRAM

metheoneandonly


Bakalaou

#5
Feb 20, 2016, 02:06 am Last Edit: Feb 20, 2016, 02:40 am by Bakalaou Reason: This is real tri-state 1990's sram
You need 8 digital pins for the I/O lines, and 3 for the control lines - one each for Chip Enable, Output Enable, and Read/Write.  That leaves you with only 3 open pins for address lines using an Arduino Pro mini.  So unless you only need 8 bytes of memory or you are up for building a whole lot of extra shifting circuitry, you should get a board with more digital pins!

I'm working with a very similar style SRAM with an Arduino Mega.  My chip is a Dual Port SRAM, but aside from that works on the same old fashion address line approach as the chip you are looking at.  I'm having some trouble with glitches in an automobile application, but outside of the environment issues I'm having, it works great.  You can have a look at how I went about it here:

Occasional error reading from AM2130/IDT7132 Dual Port SRAM
I have similar 28 and 32 pin srams from 386/486 motherboards - I have 36 of the W24M257AK-15 part, 32 of the TC5565PL-15, and 14 of the UM61512AK-15 (32-pins).

I wish to ask a bit more..  If I use the 3 control lines you mentioned and shift out the address on two cascaded 8-bit shift registers with another 2 pins, that still leaves me with one more pin plus I still have use of the 8 data pins as output only (when the output enable line leaves the sram in tri-state mode). Does this sound feasible?




chucktodd

I have similar 28 and 32 pin srams from 386/486 motherboards - I have 36 of the W24M257AK-15 part, 32 of the TC5565PL-15, and 14 of the UM61512AK-15 (32-pins).

I wish to ask a bit more..  If I use the 3 control lines you mentioned and shift out the address on two cascaded 8-bit shift registers with another 2 pins, that still leaves me with one more pin plus I still have use of the 8 data pins as output only (when the output enable line leaves the sram in tri-state mode). Does this sound feasible?

To use the W24M257AK-15 you need to supply 15bits of address, 8 bits of data, 3 control signals So that is 26 pins.  Since The UNO only has 20 more electronics is needed.

You could build a circuit with 3 74C594 to output A0..A14, D0..D7, 1 74HC589 to input D0..D7 and assorted glue logic but Why?

I would just spend $1.50 for a 64KB SPI RAM that just uses the 3 SPI pins and one more pin for CS.  Another $0.60 would get you a 23LC1024 128K SPI Ram.

Chuck.
Currently built mega http server, Now converting it to ESP32.

Bakalaou

At that price serial ram is kind of convincing... Still it's a shame that I have all these srams...

A feasible niche app might be storing waveform samples in a fast 64kB buffer (UM61512AK's) using 16-pins:

Two cheap counters for 16-bit addressing as 16 fast wrap around buffers of 4KB each.

2 pins are count/reset on a 12-bit CD4040B ripple counter,
3 pins are count/up-down/reset on a 4-bit 74C193 to select each 4kB segment,
3 pins to control the sram as mentioned
8 pins read/write data

Total = 16 pins
(8 can be latched outputs when tri-state sram is not being accessed) 74LS244 ?

michelkeijzers

I would just spend $1.50 for a 64KB SPI RAM that just uses the 3 SPI pins and one more pin for CS.  Another $0.60 would get you a 23LC1024 128K SPI Ram.

Where can I find this? If I check ebay it cost like $7 (http://www.ebay.nl/sch/i.html?_from=R40&_sacat=0&_nkw=23LC1024&rt=nc&LH_PrefLoc=2&_trksid=p2045573.m1684) ... or is the price of RAM increased much?

chucktodd

Currently built mega http server, Now converting it to ESP32.

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