Post by thread:Serial SRAM

In message <01bd2b1d$ee49c5a0$24d31ecb@desktop> spam_OUTPICLISTTakeThisOuTMITVMA.MIT.EDU writes: > > Hi > Has anyone had any experience in using serial SRAM and the pic74? =20 > Im building a project that requires about 2k x 8 RAM and I need nearly > all of my I/O. > Thanks > .....reaperKILLspam@spam@southwest.com.au Reaper, In the past I would have recommended serial FRAM for your application. However, I have had some difficulty getting hold of parts recently, so would advise caution before designing them into a product. Regards, Mike Watson -- Denison Mayes Group

On Tue, 27 Jan 1998 20:20:18 +0800 Justin Grimm <reaperKILLspamSOUTHWEST.COM.AU> writes: >Has anyone had any experience in using serial SRAM and the pic74? >=20 >Im building a project that requires about 2k x 8 RAM and I need nearly >all of my I/O. Let me know if you find one! I finally ended up using the Dallas RamPort in several projects. Harold _____________________________________________________________________ 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 Or call Juno at (800) 654-JUNO [654-5866]

Solutions Cubed has a pcba providing this function. About $30. See their product line at http://www.dcs-chico.com/~solcubed/ At 01:12 PM 1/27/98 EST, you wrote: {Quote hidden}>On Tue, 27 Jan 1998 20:20:18 +0800 Justin Grimm <.....reaperKILLspam.....SOUTHWEST.COM.AU> >writes: > > >>Has anyone had any experience in using serial SRAM and the pic74? >>=20 >>Im building a project that requires about 2k x 8 RAM and I need nearly >>all of my I/O. > > Let me know if you find one! I finally ended up using the Dallas >RamPort in several projects. > >Harold > >_____________________________________________________________________ >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 >Or call Juno at (800) 654-JUNO [654-5866] > >

I recall (but didn't save it, of course <G>) a thread a while back about serial SRAM. I'm looking for a serial SRAM part which will store, say, 2KB of data. My own research shows up FLASH and EEPROM, but due to the large number of rewrites and the speed I need it perform, neither technology will suffice. Naturally, low power (Li battery backup) would be ideal. Thanks. Andy OH yes, mandatory political comment to generate responses. "I think Bill Gates is the best thing for the computer industry." HACK COUGH <G> ================================================================== Andy Kunz - Statistical Research, Inc. - Westfield, New Jersey USA ==================================================================

In a message dated 12/4/98 11:42:40 AM Pacific Standard Time, EraseMEmtdesignspam_OUTTakeThisOuTFAST.NET writes: << I recall (but didn't save it, of course <G>) a thread a while back about serial SRAM. I'm looking for a serial SRAM part which will store, say, 2KB of data. My own research shows up FLASH and EEPROM, but due to the large number of rewrites and the speed I need it perform, neither technology will suffice. Naturally, low power (Li battery backup) would be ideal. Thanks. Andy OH yes, mandatory political comment to generate responses. "I think Bill Gates is the best thing for the computer industry." HACK COUGH <G> >> Hi Andy! Philips makes some smaller than 2K I2C serial RAM. I think they are 256 bytes. You can address up to eight of them together. The other thing that I have seen is a serial Ram module. I saw it on the Parallax site. Also there is FRAM by ramtron. These act like the old core memory. They are good for several billion reads and writes. They are pin compatable with the Microchip 24 and 25 series serial eeproms. Dave Duley

Have you considered FRAM. I hear the chip density has just been increased. Data is available at RAMTRON.com. good luck, Peter Grey At 01:59 PM 4/12/98 -0500, you wrote: {Quote hidden}>I recall (but didn't save it, of course <G>) a thread a while back about >serial SRAM. > >I'm looking for a serial SRAM part which will store, say, 2KB of data. My >own research shows up FLASH and EEPROM, but due to the large number of >rewrites and the speed I need it perform, neither technology will suffice. > >Naturally, low power (Li battery backup) would be ideal. > >Thanks. > >Andy > >OH yes, mandatory political comment to generate responses. "I think Bill >Gates is the best thing for the computer industry." > >HACK COUGH <G> > >================================================================== >Andy Kunz - Statistical Research, Inc. - Westfield, New Jersey USA >================================================================== > >

On Fri, 4 Dec 1998 17:39:38 EST, you wrote: >In a message dated 12/4/98 11:42:40 AM Pacific Standard Time, >mtdesignspam_OUTFAST.NET writes: > ><< I recall (but didn't save it, of course <G>) a thread a while back about > serial SRAM. > > I'm looking for a serial SRAM part which will store, say, 2KB of data. My > own research shows up FLASH and EEPROM, but due to the large number of > rewrites and the speed I need it perform, neither technology will suffice. > How many rewrites ? How fast ? How many at a time? Remember that Microchip guarantee 1 million cycles on their EE's, and some devices have high endurance 10million cycle blocks. Most have write caches to allow writes of up to 8-64 (depending on part) bytes at a time.

On Sat, 5 Dec 1998, Mike Harrison wrote: > How many rewrites ? How fast ? How many at a time? > Remember that Microchip guarantee 1 million cycles on their EE's, and > some devices have high endurance 10million cycle blocks. > Most have write caches to allow writes of up to 8-64 (depending on > part) bytes at a time. How about getting the relevant pdf. docs and reading about all that from http://www.ramtron.com/ ? One thing I did not know is, that FRAM also has a limited read cycle count. I haven't gotten around to read all this yet, however. Peter

>Philips makes some smaller than 2K I2C serial RAM. I think they are 256 >bytes. You can address up to eight of them together. Too much board space, Dave. >The other thing that I have seen is a serial Ram module. I saw it on the >Parallax site. I'll have to check that out. >Also there is FRAM by ramtron. These act like the old core memory. They are >good for several billion reads and writes. They are pin compatable with the >Microchip 24 and 25 series serial eeproms. If you can get them. I've only managed samples and outrageous lead tiems. They must be made by Mot <G> ANdy ================================================================== Andy Kunz - Montana Design - http://www.users.fast.net/~montana ==================================================================

On Sun, 6 Dec 1998, Paul B. Webster VK2BZC wrote: > Hello Peter. > > > One thing I did not know is, that FRAM also has a limited read cycle > > count. I haven't gotten around to read all this yet, however. > > It's very simple. It's miniature "core" memory. Reads are performed > as writes with sense lines. Therefore read endurance = write endurance. If so, then why does it have a lifetime at all (on a human scale) ?! Last time I checked the core memories from way back are in tip top condition to this day and will probably outlast any silicon structure given the same packaging and environmental care. The only thing that dies in a core memory is the line driver/read amplifier, and only if improperly designed. Even data retention is not a problem. Just use EDC in the storage and rewrite the array with correction every 2 years or so. ;) ? Peter

Peter L. Peres wrote: >>> One thing I did not know is, that FRAM also has a limited read cycle >>> count. >> It's very simple. It's miniature "core" memory. Reads are >> performed as writes with sense lines. > If so, then why does it have a lifetime at all (on a human scale) ?! Don't ask me! It seems to be related to why EEPROM has a lifetime. Doing funny things repeatedly to a microscopic structure appears to let bits leak out (literally - as molecules/ atoms). It pushes too hard. Don't ask me! -- Cheers, Paul B.

In a message dated 12/5/98 7:02:25 PM Pacific Standard Time, @spam@mtdesignKILLspamFAST.NET writes: << If you can get them. I've only managed samples and outrageous lead tiems. They must be made by Mot <G> ANdy >> Hi Andy I hear you here. I hear Motorolla just announced that they were discontinuing almost all of their 68705 cpus and several 6811 derivatives. The 68705 is a sucky cpu anyway but it will send alot of people running for somthing new that have been using these things for years. The Frams have been around for a number of years. I wonder why they havent more of a following than they do? The parallax thing is by Soulution Cubed and is a 8K X 8 module that is spoken to serially. It lookes like it is logic level standard rs232 type serial. Kinda large though. Dave Duley

Dave, Motorola is still pushing a lot of 6805-based cores for dedicated applications. Though I love the 68HC11 it probably takes a few decades to get production quantities unless you make cars and trucks... FRAMs, in my humble opinion, have failed to gain general acceptance due to their price, their inability to provide production quantities, and the advances in FLASH technology. Despite earlier comments, FRAMs have absolutely no resemblance to magnetic core memory of long ago. They used ferrite rings with a couple of select wires and a sense wire. - Tom At 02:33 AM 12/7/98 EST, Dave Duley wrote: {Quote hidden}>In a message dated 12/5/98 7:02:25 PM Pacific Standard Time, KILLspammtdesignKILLspamFAST.NET >writes: > ><< > If you can get them. I've only managed samples and outrageous lead tiems. > They must be made by Mot <G> > > ANdy > >> >Hi Andy >I hear you here. I hear Motorolla just announced that they were discontinuing >almost all of their 68705 cpus and several 6811 derivatives. The 68705 is a >sucky cpu anyway but it will send alot of people running for somthing new that >have been using these things for years. > >The Frams have been around for a number of years. I wonder why they havent >more of a following than they do? > >The parallax thing is by Soulution Cubed and is a 8K X 8 module that is spoken >to serially. It lookes like it is logic level standard rs232 type serial. >Kinda large though. > >Dave Duley > >

>>Hi Andy >>I hear you here. I hear Motorolla just announced that they were discontinuing >>almost all of their 68705 cpus and several 6811 derivatives. The 68705 is a >>sucky cpu anyway but it will send alot of people running for somthing new that >>have been using these things for years. >>Dave Duley Where did you hear this from? I am using 68HC705C8A in a few applications and get worried... I checked Motorola websites and there was not a mention about discontinuing. Will call my distributor and ask. Juha Tuomi Finland

I'm thinking of just using a couple 8 bit serial in parallel out shift registers to drive address (and maybe control lines) of the SRAM, and using 8 bits of I/O on the PIC. Serializing the address lines could save a lot of pins. Tristating the data lines could allow them to be used for some other purposes (reading switches through resistors or something like that). A serial SRAM would sure be nice! EDN ran a special section on SRAMs in a recent edition, but did not mention serial SRAMs. I wrote the author. He replied that he thought the die size of a large SRAM (say 32 Kbyte) was too large to fit in a small package (like maybe 8 pin DIP), so they needed the larger package and just used the pins that came with the larger package. I don't really mind the larger pacakge, I just don't want to use all my PIC pins! Harold Harold Hallikainen RemoveMEharoldTakeThisOuThallikainen.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]

On Tue, 8 Dec 1998, Harold Hallikainen wrote: > I'm thinking of just using a couple 8 bit serial in parallel out > shift registers to drive address (and maybe control lines) of the SRAM, > and using 8 bits of I/O on the PIC. Serializing the address lines could > save a lot of pins. Tristating the data lines could allow them to be > used for some other purposes (reading switches through resistors or > something like that). Actually using a CMOS counter will be faster (1..2 x 4040) but makes jumping backwards complicated (long live caches and structured programming w/o subroutines). I have used a combination of these on occasion (high 14 addresses from 4040, low 4 direct from micro). It is possible to use a serializer for the data too, but it makes it very slow and CPU-intensive. I think that a PIC 64 is what is needed. It can be used to address a large device and still have pins left. (I used such a PIC for similar purposes). The C64 has enough oomph to drive even a 32 MB SIMM with some time left over, and some pins left over. I might also mention that a HCT373 or two can be used to reduce the data and address IO pin count to 8 using 8031-style ALE-latching. Only 1 strobe pin is required (the latch devices are in series and supply addresses only to the target SRAM). Addressing is pretty fast under the circumstances. If one uses 'Ohm' type gates <G> on the memory D I/O then only 2 wires are required to control the device with up to 64k x 8 and this is in range for a F84. One control wire supplies the strobe pulses to the address latches, and also drives the CS of the RAM (to allow bus muxing if req'd), the second is wired directly to ~WE on the RAM. 2 IO pins remain free for general use (serial ?). hope this helps, Peter

On Tue, 8 Dec 1998 19:49:22 +0200, juha tuomi <spamBeGonejuha.tuomispamBeGoneliperi.fi> wrote: >>>Hi Andy >>>I hear you here. I hear Motorolla just announced that they were >discontinuing >>>almost all of their 68705 cpus and several 6811 derivatives. The 68705 is >a >>>sucky cpu anyway but it will send alot of people running for somthing new >that >>>have been using these things for years. > >>>Dave Duley > > > >Where did you hear this from? I am using 68HC705C8A in a few applications >and get worried... I checked Motorola websites and there was not a mention >about discontinuing. Will call my distributor and ask. While I was finishing up a project using the 68HC05C0, Motorola announced to its users that they plan on discontinuing most of the 6805 line. It seemed only those products that were sold in the millions would be continued. We were assured that our product would be one of those. Unfortunately, I don't have a list of affected processors. Two months later we were told that the 68HC05C0 would be discontinued (throwing away two years of work and a few million in investment dollars). After discussions between Motorola, and the head of the company I'm contracting for, it was agreed that the 68HC05C0 would be continued. But this most likely because the product I'm working on (a remote control for cable boxes) will be sold in the millions -- and that the company I'm working for is also very closely associated with another company that uses in upwards of 10's of millions of Motorola 6805 parts per year (also remote controls). If you're currently using a 6805 family part (especially if you're in the design phase) I suggest you check with Motorola to see if they plan on continuing the part. Their first response will be "Yes of course" (They can't help it, they're Motorola). Try them again a month later -- if you can reach them, once again this Motorola were talking about. And who knows, by now there might be a whole change of plan, and the 6805 might be their "New Part into the New Millennium!", doubtful, but this *IS* Motorola! -Zonn <><><><><><><><><><><><><><><><><><><><><><><><><><><>< ------ ___ Member of A.A.C.S.: |---- | ( ) Association for Artistically / / ( () ) Challenged Signatures / / //\\ // (__) / ---/ // \\ //\\ // zonn @ zonn . com -------| // \\/

Thanks, Zonn Regards, Juha -----Original Message----- From: Zonn <TakeThisOuTzonnEraseMEspam_OUTZONN.COM> To: RemoveMEPICLISTTakeThisOuTMITVMA.MIT.EDU <PICLISTEraseME.....MITVMA.MIT.EDU> Date: 8. joulukuuta 1998 22:07 Subject: Re: Serial SRAM While I was finishing up a project using the 68HC05C0, Motorola announced to its users that they plan on discontinuing most of the 6805 line. And who knows, by now there might be a whole change of plan, and the 6805 might be their "New Part into the New Millennium!", doubtful, but this *IS* Motorola! -Zonn

At 13:59 12/04/98 -0500, you wrote: >I'm looking for a serial SRAM part which will store, say, 2KB of data. My >own research shows up FLASH and EEPROM, but due to the large number of >rewrites and the speed I need it perform, neither technology will suffice. > >Naturally, low power (Li battery backup) would be ideal. did you find any yet? if 400kHz access speed is enough (write operations at bus speed), you might have a look at the http://www.ramtron.com fram devices. no battery backup needed, it seems. (i don't know them, just stumbled over the info somewhere.) ge

At 10:01 AM 12/10/98 -0800, you wrote: >At 13:59 12/04/98 -0500, you wrote: >>I'm looking for a serial SRAM part which will store, say, 2KB of data. My >>own research shows up FLASH and EEPROM, but due to the large number of >>rewrites and the speed I need it perform, neither technology will suffice. >> >>Naturally, low power (Li battery backup) would be ideal. > >did you find any yet? if 400kHz access speed is enough (write operations at >bus speed), you might have a look at the http://www.ramtron.com fram devices. no >battery backup needed, it seems. (i don't know them, just stumbled over the >info somewhere.) No, Gerhard, I haven't. The best I can find so far (and "best" includes "can actually purchase in 20K volume") is the Phillips PCF8570. Andy ================================================================== Andy Kunz - Statistical Research, Inc. - Westfield, New Jersey USA ==================================================================

In a message dated 12/10/98 11:01:12 AM Pacific Standard Time, RemoveMEmtdesignEraseMEEraseMEFAST.NET writes: << No, Gerhard, I haven't. The best I can find so far (and "best" includes "can actually purchase in 20K volume") is the Phillips PCF8570. Andy >> Hi ANDY! Since I am looking for somthing similar, I found the Dallas DS2404. It has twice the ram as the Philips part and has a real time clock as well. It will work with the 1 wire protocol or a 3 wire protocol or both. It also has a 48 bit unique serial number rom. They are $3.89 in 1000 piece qty. Dave Duley Dreitek Inc. http://www.dreitek.com

This problem seems to be back. In an 11.3AA image, I get a crash one minute FOLLOWING the random telnet connection: Program received signal SIGBUS, Bus error. 0x105284 in timer_running () (cisco-68k-gdb) bt #0 0x105284 in timer_running () #1 0xe5618 in notify_state_change () #2 0x4640ce in xot_context_detach () #3 0x469bde in xot_timed_wakeup () #4 0x450bc8 in x25lib_task () For cs-x25: make a telnet connection to a router configured for x25 routing, and type quit<return> BillW

At 11:07 AM 12/10/98 -0800, you wrote: >What about Atmel's DataFlash (SPI interface)? Datasheets on the Atmel >website (http://www.atmel.com). >I requested a sample kit from our local distributor and will meet with an >Atmel rep tomorrow. > >Has anyone used these DataFlash parts? Yes, I have. They work nice. Problem is that they tend to take a while to burn, and I don't have that much time to do it when the power is failing. Andy ================================================================== Andy Kunz - Statistical Research, Inc. - Westfield, New Jersey USA ==================================================================

In a message dated 12/11/98 6:00:08 AM Pacific Standard Time, RemoveMEmtdesignspam_OUTKILLspamFAST.NET writes: << >Since I am looking for somthing similar, I found the Dallas DS2404. It has Thanks, Dave, I'll check it out. My inside guy at Dallas didn't know about it. Andy >> Hi Andy, Dallas is pretty cool about small quantities. They have online ordering for items upto $250 or 10 pieces directly. This is way cool if youv'e ever(and I know you have) tried to get 5 parts out of anybody for evaluation. I ordered 10 of the DS2404s yesterday. They were in stock. good luck Dave Duley

I worked for Delco in Santa Barbara in 1988. THEY definitely had production quantities of 68hc11's. It was only a decade a ago... maybe they have some to spare now.... JG -----Original Message----- From: pic microcontroller discussion list [RemoveMEPICLISTTakeThisOuTspamMITVMA.MIT.EDU]On Behalf Of Tom Handley Dave, Motorola is still pushing a lot of 6805-based cores for dedicated applications. Though I love the 68HC11 it probably takes a few decades to get production quantities unless you make cars and trucks...