Post by thread:(OT) Timekeeper (R) RAM alternative ?

I use the Timekeeper (R) RAM in a PIC project (so this is just a little off topic - OK ?) The advantage is a classic, useful scratchpad, with a 10 year clock on top (year month ....) both are very valuable for this project. The disadvantage is, that the 32 K memory needs 15 addresslines, and thus a hairy PCB. Either I need to use latches or drivers (or use up the I/O ports of the PIC) to address this special RAM. Now - have anyone of you seen a serially (SPI ??) addressable RAM / timer combination out there ? Best Regards Sven

ST Microelectronics makes the M41T11, its a I2C clock calendar plus 56 bytes of RAM. It has all the backup battery switching built in, but not the battery itself. It uses a watch crystal and has a cool digital calibration trick to do accuracy trim. They have a web site, but I don't have the URL handy. AltaVista can find 'em. ------------ Barry King, KA1NLH Engineering Manager NRG Systems "Measuring the Wind's Energy" Hinesburg, Vermont, USA spam_OUTbarryTakeThisOuTnrgsystems.com "The witty saying has been deleted due to limited EPROM space"

Philips offers the PCF8553 clock/calendar with 240*8bit ram and the PCF8593 low power version with 8byte ram. Try http://www-us.semiconductors.philips.com/ Leo <.....salsaterKILLspam@spam@dds.nl> ---------- > From: MILTON MEDICINTEKNIK KB <milton.medicinteknikKILLspamTELIA.COM> > To: .....PICLISTKILLspam.....MITVMA.MIT.EDU > Subject: SV: (OT) Timekeeper (R) RAM alternative ? > Date: Thursday, May 13, 1999 6:08 PM > > I use the Timekeeper (R) RAM in a PIC project (so this is just a little off topic - OK ?) The advantage is a classic, useful scratchpad, with a 10 year clock on top (year month ....) both are very valuable for this project. The disadvantage is, that the 32 K memory needs 15 addresslines, and thus a hairy PCB. Either I need to use latches or drivers (or use up the I/O ports of the PIC) to address this special RAM. > > Now - have anyone of you seen a serially (SPI ??) addressable RAM / timer combination out there ? > > Best Regards > > Sven

I >I use the Timekeeper (R) RAM in a PIC project (so this is just a little off topic - OK ?) The advantage is a classic, useful scratchpad, with a 10 year clock on top (year month ....) both are very valuable for this project. The disadvantage is, that the 32 K memory needs 15 addresslines, and thus a hairy PCB. Either I need to use latches or drivers (or use up the I/O ports of the PIC) to address this special RAM. > >Now - have anyone of you seen a serially (SPI ??) addressable RAM / timer combination out there ? > >Best Regards > >Sven > > I am developing a project using the Dallas Semiconductor DS1307 RTC. 56 bytes of battery backed RAM and I2C bus. Cheers JD

Leo TImmer wrote: > > Philips offers the PCF8553 clock/calendar with 240*8bit ram and the PCF8593 > low power version with 8byte ram. Try > http://www-us.semiconductors.philips.com/ > Leo It is a nice chip, but watch out - if you inadvertantly write '11' to the setup bits, you're screwed. '11' Puts the chip into a test mode, and you have to power-cycle it to get it to recover. This 'feature' is pretty dangerous if you have a volume application. -- Friendly Regards /"\ \ / Tjaart van der Walt X ASCII RIBBON CAMPAIGN EraseMEtjaartspam_OUTTakeThisOuTwasp.co.za / \ AGAINST HTML MAIL |--------------------------------------------------| | Cellpoint Systems SA | | http://www.cellpt.com | |--------------------------------------------------| | http://www.wasp.co.za/~tjaart/index.html | |Voice: +27-(0)11-622-8686 Fax: +27-(0)11-622-8973| | WGS-84 : 26¡10.52'S 28¡06.19'E | |--------------------------------------------------|

At 07:02 17/05/99 +0200, you wrote: {Quote hidden}>Leo TImmer wrote: >> >> Philips offers the PCF8553 clock/calendar with 240*8bit ram and the PCF8593 >> low power version with 8byte ram. Try >> http://www-us.semiconductors.philips.com/ >> Leo > >It is a nice chip, but watch out - if you inadvertantly >write '11' to the setup bits, you're screwed. '11' Puts >the chip into a test mode, and you have to power-cycle >it to get it to recover. This 'feature' is pretty >dangerous if you have a volume application. > >-- >Friendly Regards /"\ > \ / >Tjaart van der Walt X ASCII RIBBON CAMPAIGN >tjaartspam_OUTwasp.co.za / \ AGAINST HTML MAIL >|--------------------------------------------------| >| Cellpoint Systems SA | >| http://www.cellpt.com | >|--------------------------------------------------| >| http://www.wasp.co.za/~tjaart/index.html | >|Voice: +27-(0)11-622-8686 Fax: +27-(0)11-622-8973| >| WGS-84 : 26¡10.52'S 28¡06.19'E | >|--------------------------------------------------| > > Hey, Tjaart; why should there be a difference between a one off application and a "Volume" application in this case? Nasty features like that can cause trouble at any point in time. Could be interesting if your micro has taken a long walk of a short pier into the inevitable bliss of electronic wonderland. There be no recovery for this one opps, no defensive code recovery eh? Dennis

Dennis Plunkett wrote: {Quote hidden}> > At 07:02 17/05/99 +0200, you wrote: > >Leo TImmer wrote: > >> > >> Philips offers the PCF8553 clock/calendar with 240*8bit ram and the PCF8593 > >> low power version with 8byte ram. Try > >> http://www-us.semiconductors.philips.com/ > >> Leo > > > >It is a nice chip, but watch out - if you inadvertantly > >write '11' to the setup bits, you're screwed. '11' Puts > >the chip into a test mode, and you have to power-cycle > >it to get it to recover. This 'feature' is pretty > >dangerous if you have a volume application. > Hey, Tjaart; why should there be a difference between a one off application > and a "Volume" application in this case? > Nasty features like that can cause trouble at any point in time. Could be > interesting if your micro has taken a long walk of a short pier into the > inevitable bliss of electronic wonderland. There be no recovery for this > one opps, no defensive code recovery eh? Well, if you are watering your garden with it, you'll notice it soon enough (slop, slop). If you have an installed base of a few thousand or more, you had better get to the airport.... ;) I have tried everything (software wise) to get it to recover, but it won't. Period. I have built-in checks at two different levels to prevent this from happening in my software. -- Friendly Regards /"\ \ / Tjaart van der Walt X ASCII RIBBON CAMPAIGN @spam@tjaartKILLspamwasp.co.za / \ AGAINST HTML MAIL |--------------------------------------------------| | Cellpoint Systems SA | | http://www.cellpt.com | |--------------------------------------------------| | http://www.wasp.co.za/~tjaart/index.html | |Voice: +27-(0)11-622-8686 Fax: +27-(0)11-622-8973| | WGS-84 : 26¡10.52'S 28¡06.19'E | |--------------------------------------------------|

Thanks, but not exactly what I needed. I would like to combine the timer with a 8 KB RAM. However... I agree with you that this looks nice. I might rec—nsider the design. Kindest regards Sven -----Ursprungligt meddelande----- FrŒn: John Duncan <KILLspamj.duncanKILLspamBOM.GOV.AU> Till: RemoveMEPICLISTTakeThisOuTMITVMA.MIT.EDU <spamBeGonePICLISTspamBeGoneMITVMA.MIT.EDU> Datum: den 17 maj 1999 04:57 €mne: Re: SV: (OT) Timekeeper (R) RAM alternative ? {Quote hidden}>I >>I use the Timekeeper (R) RAM in a PIC project (so this is just a little >off topic - OK ?) The advantage is a classic, useful scratchpad, with a 10 >year clock on top (year month ....) both are very valuable for this >project. The disadvantage is, that the 32 K memory needs 15 addresslines, >and thus a hairy PCB. Either I need to use latches or drivers (or use up >the I/O ports of the PIC) to address this special RAM. >> >>Now - have anyone of you seen a serially (SPI ??) addressable RAM / timer >combination out there ? >> >>Best Regards >> >>Sven >> >> > >I am developing a project using the Dallas Semiconductor DS1307 RTC. 56 >bytes of battery backed RAM and I2C bus. > >Cheers >JD >