Post by thread:Serial (SPI or I2C) SRAM

Check out http://www.microchip.com/10/Lit/Memory/index.htm for Microchips chips. But atmel make a large SPI flash ram which seems it could be a good thing, I have a couple to try but as yet have not had time. They are AT45D041 4 megabit 5 volt serial flash and ATD161 16 Megabit 5Volt serial flash. Although i have not been able to get hold of the 16Mb chip as yet. All data sheets are on the Atmel site. There is/was a site http://www.questlink.com which was great but I can't seem to get onto it. But you can search for alsorts of devices and get the data sheets. Hope this helps Jason >Does anybody know a large Serial (SPI or I2C) Static RAM (SRAM) >manufacturers. > >I am trying to interface it to the PIC and I don't want to use parallel >version which will take up one whole port just for RAM instead of 2 for I2C. > >I am looking for at least 32k X 8. > >Thank you. > >S. Paramananthan > >

Hi Jason, Thank you for your e-mails. I'm afraid they don't have Serial SRAM, They do however have Flash Memory & EEPROM. I'm particularly looking for SRAM because I don't want 7 -10ms time delay while writing data. PIC has limited RAM but I need lot RAM for my signal processing project. Thank you. Best regards Saba {Original Message removed}

On Thu, 19 Nov 1998 01:28:41 -0000 Sabananthan Paramananthan <spam_OUTsabananthanTakeThisOuTdial.pipex.com> writes: >Hi Jason, > >Thank you for your e-mails. > >I'm afraid they don't have Serial SRAM, They do however have Flash >Memory & >EEPROM. > >I'm particularly looking for SRAM because I don't want 7 -10ms time >delay >while writing data. PIC has limited RAM but I need lot RAM for my >signal >processing project. The lack of serial RAM chips for use with the PIC has been a problem for years. I finally went with the Dallas RamPort for existing projects, but could still use a serial RAM. The RamPort is only 2Kbytes and uses 11 I/O lines (though it repeats 8 of them so they can continue to be used as I/O lines). SOMEBODY otta make BIG (32 K bytes or more) serial RAM! Harold Harold Hallikainen .....haroldKILLspam@spam@hallikainen.com Hallikainen & Friends, Inc. See the FCC Rules at http://hallikainen.com/FccRules and comments filed in LPFM proceeding at http://hallikainen.com/lpfm ___________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com/getjuno.html or call Juno at (800) 654-JUNO [654-5866]

| The lack of serial RAM chips for use with the PIC has been a |problem for years. I finally went with the Dallas RamPort for existing |projects, but could still use a serial RAM. The RamPort is only 2Kbytes |and uses 11 I/O lines (though it repeats 8 of them so they can continue |to be used as I/O lines). You may want to check out http://www.ramtron.com for information about their "FRAM" products. They may fit your needs nicely. They offer moderate-sized (2Kx8) non-volatile I2C/SPI memories in an 8-pin package at reasonable prices. Advantages over EEPROM devices: 10^13 write cycle endurance Writes happen immediately, as fast as you clock in data Disadvantages over EEPROM devices: 10^13 read cycle endurance (actually 10^13 writes + reads) Writes happen immediately, as fast as you clock in data Note that unlike EEPROMs, which will hold a number of bytes in a "page" buffer until a valid I2C "stop" is received, and which will disregard any attempted write operation which does not end with a properly-placed stop condition, the FRAM devices write each byte of data immediately following the acknowlege pulse. As a consequence, it is possible for much or all of the device to get accidentally overwritten if the CPU behaves badly under power-down conditions. For your application, though, it sounds as though the FRAM devices may be quite adequate. Visit <http://www.ramtron.com> for more information. Attachment converted: wonderland:WINMAIL.DAT (????/----) (0001E76F)

I have also been looking for serial sram to use with a data aquisition application. I would like to read an A/D then store it in sram really fast, how fast are the fastest sram chips that you have seen and what are they? Thanks. Jon Newport Sabananthan Paramananthan wrote: {Quote hidden}> > Does anybody know a large Serial (SPI or I2C) Static RAM (SRAM) > manufacturers. > > I am trying to interface it to the PIC and I don't want to use parallel > version which will take up one whole port just for RAM instead of 2 for I2C. > > I am looking for at least 32k X 8. > > Thank you. > > S. Paramananthan

On Thu, 26 Nov 1998 01:59:12 -0800 MARK D NEWPORT <jmnewpKILLspamworldnet.att.net> writes: >I have also been looking for serial sram to use with a data aquisition >application. I would like to read an A/D then store it in sram really >fast, how fast are the fastest sram chips that you have seen and what >are they? Thanks. Most of the serial flash chips can accept data much faster than a PIC could send it (megabits per second) because they use a page write scheme which writes a couple hundred bytes at a time. But since it is flash not SRAM you have to wonder about wearout if the writing is constantly repeated. The manufacturers seem reluctant to quote a life expectancy in their data sheets. ___________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com/getjuno.html or call Juno at (800) 654-JUNO [654-5866]

On Thu, 26 Nov 1998 01:59:12 -0800 MARK D NEWPORT <.....jmnewpKILLspam.....worldnet.att.net> writes: >I have also been looking for serial sram to use with a data aquisition >application. I would like to read an A/D then store it in sram really >fast, how fast are the fastest sram chips that you have seen and what >are they? Thanks. Most of the serial flash chips can accept data much faster than a PIC could send it (megabits per second) because they use a page write scheme which writes a couple hundred bytes at a time. But since it is flash not SRAM you have to wonder about wearout if the writing is constantly repeated. The manufacturers seem reluctant to quote a life expectancy in their data sheets. ___________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com/getjuno.html or call Juno at (800) 654-JUNO [654-5866]

Hi, there is an SRAM from Philips, I guess PCF8570 or 8750 or similar. However, it has a limited storage size... :-( Imre On Fri, 27 Nov 1998, Mike Keitz wrote: {Quote hidden}> On Thu, 26 Nov 1998 01:59:12 -0800 MARK D NEWPORT > <EraseMEjmnewpspam_OUTTakeThisOuTworldnet.att.net> writes: > >I have also been looking for serial sram to use with a data aquisition > >application. I would like to read an A/D then store it in sram really > >fast, how fast are the fastest sram chips that you have seen and what > >are they? Thanks. > > Most of the serial flash chips can accept data much faster than a PIC > could send it (megabits per second) because they use a page write scheme > which writes a couple hundred bytes at a time. But since it is flash not > SRAM you have to wonder about wearout if the writing is constantly > repeated. The manufacturers seem reluctant to quote a life expectancy in > their data sheets. > > ___________________________________________________________________ > You don't need to buy Internet access to use free Internet e-mail. > Get completely free e-mail from Juno at http://www.juno.com/getjuno.html > or call Juno at (800) 654-JUNO [654-5866] > >