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'512 KByte of memory'
1995\10\31@060923 by Mikael Lundqvist

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Hi everybody,

I'm working on a data aquisition project with a PIC uC involved.
Does anybody have an idea about if it's possible to attatch
512 KBytes of NV- Data Memory to any pic controller and if how
then how ?? (this sounds stupid!)
I would be realy glad if somebody has any idea (If 512 is difficult,
then what about 256,128 or 64KBytes)

               Ciao
                       Mikael

1995\10\31@075546 by Pic User

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face
>
> Hi everybody,
>
> I'm working on a data aquisition project with a PIC uC involved.
> Does anybody have an idea about if it's possible to attatch
> 512 KBytes of NV- Data Memory to any pic controller and if how
> then how ?? (this sounds stupid!)
> I would be realy glad if somebody has any idea (If 512 is difficult,
> then what about 256,128 or 64KBytes)
>
>                 Ciao
>                         Mikael
>

I think its not possible.
The Basic Stamp can't write an address that high.
You won't be able to store data in a location if you can't write
the address.

You can put a 256 byte EEPROM on each IO pin, and write to those, but that
still doesn't give you the storage you want.

1995\10\31@080209 by David Knell

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face
>I'm working on a data aquisition project with a PIC uC involved.
>Does anybody have an idea about if it's possible to attatch
>512 KBytes of NV- Data Memory to any pic controller and if how
>then how ?? (this sounds stupid!)
>I would be realy glad if somebody has any idea (If 512 is difficult,
>then what about 256,128 or 64KBytes)

Dallas semiconductor do some nifty DRAM nonvolatisers, which might
be your answer - they take care of refreshing the RAM, cope with main
system power failure (you do, of course, need to supply backup power
to the RAM and the controller) and provide a serial interface (1-wire?
2-wire?) to the RAM which is ideal for use with a PIC.

If I can find the databook I'll post the part numbers.

Regards,

Dave

1995\10\31@083815 by Mark A. Corio

picon face
Interfacing a PIC to 512 KBytes of memory (or more) is only a matter of
trade-offs.  How fast do you need to access this memory?  If time is not
critical you could attach a serial to parallel shift register to one I/O pin
on the PIC and shift an address into it.  You could then use another I/O pin
as a strobe and 8 I/O pins for a data bus.  I have used this approach for
smaller amounts of external memory locations and registers by replacing the
shift register with 8 I/O pins to address 256 locations.  I don't see why
this couldn't be expanded to the memory sizes you need.

Mark A. Corio
Rochester MicroSystems, Inc.
200 Buell Road, Suite 9
Rochester, NY  14624
Tel:  (716) 328-5850
Fax:  (716) 328-1144
e-mail:  spam_OUTMcorioTakeThisOuTspamaol.com

***** Designing Electronics For Research & Industry *****

1995\10\31@083819 by Mike Riendeau
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On 10/31/95 you wrote:

>Does anybody have an idea about if it's possible to attatch
>512 KBytes of NV- Data Memory to any pic controller and if how
>then how ?? (this sounds stupid!)

Dallas has a part (DS1280) in there 94-95 NV RAM data book.
It converts a 3-wire serial interface to a JEDED standard
bytewide interface for memory. It supports up to 512K.


                         Mike

1995\10\31@142601 by Don McKenzie

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face
> > I'm working on a data aquisition project with a PIC uC involved.
> > Does anybody have an idea about if it's possible to attatch
> > 512 KBytes of NV- Data Memory to any pic controller and if how
> > then how ?? (this sounds stupid!)
> > I would be realy glad if somebody has any idea (If 512 is difficult,
> > then what about 256,128 or 64KBytes)
> >                 Ciao
> >                         Mikael

You could try daisy chaining two Cmos 4040 timers together controlled by
two signals. One clock, for address selection and one for reset to zero
address.

Get an off the shelf 8 bit wide static ram that will have its data lines
connected directly to 8 PIC lines. You then only need to control the
read, write and chip select of the Ram.

Battery backup can be provided by a simple diode/resistor network from any
variety of sources such as Ni-Cad, lithium or a large capacitor. February
95 Circuit Cellar magazine gives examples of doing simple battery backups.

Or you could use a Dallas Ram backup (smart socket) if cost isn't a big
factor.

The last time I purchased Static Rams, the 128K by 8 bit was the most cost
effective, but that was perhaps 18 months ago. This may have changed.
Perhaps you can get your 512K in one IC at a realistic price.

Don...

 Low Cost DIY PCB's for PICs & COM1/LPT1 PC I/O Interface Kits    ;!
 Don McKenzie. 29 Ellesmere Cres., Tullamarine. 3043 Australia    ;@
 Tel +61 3 9338 6286 Mobile  +61 19 939 799 .....donmckKILLspamspam@spam@tbsa.com.au    ;#
 Check My Promo Disk at http://rasi.lr.ttu.ee/~sis/mirror/don/    ;$
 Type: 'finger donmckspamKILLspamtbsa.com.au|more'  for more information.

1995\10\31@160350 by Bill Cornutt

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----------


You can use a number of serial to parallel chips to create the
memory address, and use standard ram's.

But when you find that you need a specialized type of chip, why not
program a PIC chip to do the job.

  ---------
  Bill Cornutt
  .....billcornKILLspamspam.....infoserv.com
  Located in Ione California USA.
  A small town in Northern California.
  Sitting against the foothills of the Mother Lode.
  ----------------------------------------------------

1995\10\31@202136 by Prashant Bhandary

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At 12:08 PM 31/10/95 +0100, you wrote:
>Hi everybody,
>
>I'm working on a data aquisition project with a PIC uC involved.
>Does anybody have an idea about if it's possible to attatch
>512 KBytes of NV- Data Memory to any pic controller and if how
>then how ?? (this sounds stupid!)
>I would be realy glad if somebody has any idea (If 512 is difficult,
>then what about 256,128 or 64KBytes)
>
>                Ciao
>                        Mikael

Add one more suggestion to the several you have already received.
Use 4 lines for address, 4 lines for data and one for strobe.
The 4 address lines when decoded, should give you 16 lines. Attach
lataches at 5 of the addresses. This gives you a 20 bit output port.
Connect this to the 256K memeory. Use two more latches to read and
two to write data. Another address to provide the write pulse.


 Data(4) -------------------------------------------------------
                               |
                 +-------+  +--+---+
 Address(4) -----|Decoder|--|Latch1| .... more Latches
 Strobe(1)  -----|       |  +--+---+
                 |       |     |
                               |
                               |       +-------------+
                               +-------|A0-3 256K    |
                        Latch2 --------|A4-7 RAM     |
                        Latch3 --------|A8-11        |
                        Latch4 --------|A12-15       |
                        Latch5 --------|A16-19       |
                                       |             |
                        Latch6 ---+----|D0-3         |
                        Buff7  ---+    |             |
                                       |             |
                        Latch8 ---+----|D4-7         |
                        Buff9  ---+    |             |
                                       |             |
                        From decoder --|WR           |
                        10

To read
 Set address on Latches 1 to 5.
 Read buffer 7 for 1st nibble
 Read buffer 9 for 2nd nibble

To write
 Set address on Latches 1 to 5
 Set data on Latches 6 and 8
 Send write pulse by putting out address 10

Regards

Prashant
+----------------+  -------------------------------------------------
|                |    Prashant Bhandary
|   +---+        |    Spatial Information Systems Section
|   |   |        |    Roads and Traffic Authority
|   |   |        |    Rosebery NSW 2018, AUSTRALIA
|   |   |        |    Tel:  +61-2-662 5299
|   |   +----+   |    Fax:  +61-2-662 5348
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|   +--------+   |
| Still a newbie |    "2b|!2b" - William Shakespeare
+----------------+  -------------------------------------------------


'512 KByte of memory'
1995\11\01@044516 by ller%sheffield.ac.uk%UKACRL.bitnet
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If you decide to use 64k bytes rather than 512k for your data-logger, we
have built a similar device and due to pricing breaks we have a few spare
unpopulated PCBs.  The PCB measures about 25mm x 25mm x 1.5mm and is
designed to take the surface mount 16LC84 and up to eight 24LC65 64kbit
IIC eeproms.  The whole thing is powered from a lithium cell.

If you are interested we could come to some arrangement about selling on
some PCBs.

Ben Heller
Department of Medical Physics, Royal Hallamshire Hospital, Sheffield

1995\11\01@142235 by Don McKenzie

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---------- Forwarded message ---------- Your message is being returned to
you unprocessed because it seems to have been already sent to the PICLIST
list. That is, a message with identical body (but possibly different
headers) has been posted to the list recently, either by you or by someone
else.

OK, I'll add the above text! That should trick it hey?  :-))

> > I'm working on a data aquisition project with a PIC uC involved.
> > Does anybody have an idea about if it's possible to attatch
> > 512 KBytes of NV- Data Memory to any pic controller and if how
> > then how ?? (this sounds stupid!)
> > I would be realy glad if somebody has any idea (If 512 is difficult,
> > then what about 256,128 or 64KBytes)
> >                 Ciao
> >                         Mikael

You could try daisy chaining two Cmos 4040 timers together controlled by
two signals. One clock, for address selection and one for reset to zero
address. By pulsing the clock, you increment the address, an old tried
and true method!

Get an off the shelf 8 bit wide static ram that will have its data lines
connected directly to 8 PIC lines. You then only need to control the
read, write and chip select of the Ram.

Battery backup can be provided by a simple diode/resistor network from any
variety of sources such as Ni-Cad, lithium or a large capacitor. February
95 Circuit Cellar magazine gives examples of doing simple battery backups.

Or you could use a Dallas Ram backup (smart socket) if cost isn't a big
factor.

The last time I purchased Static Rams, the 128K by 8 bit was the most cost
effective, but that was perhaps 18 months ago. This may have changed.
Perhaps you can get your 512K in one IC at a realistic price.

Don...

 Low Cost DIY PCB's for PICs & COM1/LPT1 PC I/O Interface Kits    ;!
 Don McKenzie. 29 Ellesmere Cres., Tullamarine. 3043 Australia    ;@
 Tel +61 3 9338 6286 Mobile  +61 19 939 799 donmckspamspam_OUTtbsa.com.au    ;#
 Check My Promo Disk at http://rasi.lr.ttu.ee/~sis/mirror/don/    ;$
 Type: 'finger @spam@donmckKILLspamspamtbsa.com.au|more'  for more information.


'512 Kbyte of memory'
1995\12\01@114544 by Tommy Brown
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On Thu, 2 Nov 1995, PETE KLAMMER said:

Subject: : 32Kbyte NV FRAMs?
> > From: Don McKenzie <KILLspamdonmckKILLspamspamtbsa.com.au>
> > Subject: Re: 512 KByte of memory: EASIEST WAY!!!
> >
> > He said 512 Kilobytes!!
-------------clip---------clip-----------------------------
> Well, for adequate density/capacity, for one, eh?  Sorry if I got anyone's
> hopes up.
-------------clip---------clip-----------------------------

Hi, I have been following your threads on interfacing 512K x 8 memory
to PICs.

I have Dallas Semiconductor's 11 page data sheet for their 3 wire to
bytewide bus interface 1280.ps (370k).

The chip has the following features:

* Adapts JEDEC bytewide memory to a 3-wire serial port

* Supports 512k bytes of memory

* 80-pin version provides arbitration mechanisms for dual port operation

* CMOS circuitry for battery backup and battery operate applications

* Cyclic redundancy check monitors serial transmission for error

* Available in 44/80 pin quad flat pack for high density requirements

A short description from data sheet page 1, is as follows:

The DS1280 adds a 3-wire serial port to a bytewide static RAM, yet
maintains the existing bytewide port.  Memory capacity of up to 512K x 8
bytes can be addressed directly.  Arbitration between the serial and
bytewide port is accomplished by handshaking or using predictable idle
time as an access window.  The serial protocol requires a 6 byte protocol
to set up memory transfers.  Cyclic redundancy check circuitry is included
to monitor serial data transmission error.

The 3-wire serial port will correctly read and write any byte wide static
RAM with an effective access time of 200ns.

The serial interface uses bi-directional data pin (DQ), unlike other
three/four wire interfaces which have separate Data In and Data Out pins.

Data pins description follows:
___
RST             RESET FOR SERIAL PORT

Clk             CLOCK INPUT FOR SERIAL PORT

DQ              DATA INPUT/OUTPUT FOR SERIAL PORT

DQOE            SERIAL PORT ACTIVE OUTPUT       *AVAILABLE ONLY ON 44 PIN
VERSION

DQE             SERIAL PORT ACTIVE OUTPUT       *AVAILABLE ONLY ON 80 PIN
VERSION
___
CEB             SYSTEM BUS ENABLE               *AVAILABLE ONLY ON 80 PIN
VERSION
___
OEB             SYSTEM BUS READ ENABLE          *AVAILABLE ONLY ON 80 PIN
VERSION
___
WEB             SYSTEM BUS WRITE ENABLE         *AVAILABLE ONLY ON 80 PIN
VERSION

A0B-A18B        SYSTEM ADDRESS BUS              *AVAILABLE ONLY ON 80 PIN
VERSION

D0B-D7B         SYSTEM DATA BUS                 *AVAILABLE ONLY ON 80 PIN
VERSION
___
CER             RAM CHIP ENABLE
___
WER             RAM WRITE ENABLE
___
OER             RAM OUTPUT ENABLE

A0R-A18R        RAM ADDRESS BUS

D0R-D7R         RAM DATA BUS

GND             GROUND

Vcc             5 VOLTS
----------------------------------------------------------------------------
------
As you can see it is able to both access NV static ram, and the 80 pin
version can allow access to system bus of another cpu.

It appears to be good choice to expand an existing PIC design, which may
have a serial interface already implemented, but other I/O pins commited
to other tasks.

It makes at most a single chip solution to expand a PIC or any 8 bit cpu
to access additional ram.

Dallas also has chips that combine the features for cpu/ram reset for power
down or brown-out protection, with a real time clock that runs on 3V lithium
power cells when your cpu/ram is in sleep mode.

Dallas also have plug-in non/volatile read write cartridge with size up
to 512K x 8 byte, which is ideal for data-logging.  It can be inserted or
removed by non-technical persons.  It has manual read/write enable switch
in cartridge, and has hot swap feature built-in.  It is DS1217M, data sheet
is 1217M.PS (postscript).

You can retrieve full data sheets as well as application notes for these
and other chips at:

ftp.dalsemi.com/pub/datasheets/

regards

********************************************************************************
* Tom Brown
E-Mail:RemoveMEtombrownTakeThisOuTspamindo.net.id  *
* Bumi Karang Indah                                Phone: 62-21-7508264        *
* Jalan Karang Asri II,       **************************************************
* Blok C2/#43, Lebak Bulus  *    "If something is worth doing,
*
* Jakarta, Seletan 12440   *           It's worth doing right the first time"  *
* Indonesia               *                                                    *
********************************************************************************

1995\12\01@174519 by Don McKenzie

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On Fri, 1 Dec 1995, Tommy Brown wrote:
> On Thu, 2 Nov 1995, PETE KLAMMER said:
> Subject: : 32Kbyte NV FRAMs?
> > > From: Don McKenzie <spamBeGonedonmckspamBeGonespamtbsa.com.au>
> > > Subject: Re: 512 KByte of memory: EASIEST WAY!!!
> > > He said 512 Kilobytes!!
> -------------clip---------clip-----------------------------
> > Well, for adequate density/capacity, for one, eh?  Sorry if I got anyone's
> > hopes up.
> -------------clip---------clip-----------------------------
>
> Hi, I have been following your threads on interfacing 512K x 8 memory
> to PICs.
> I have Dallas Semiconductor's 11 page data sheet for their 3 wire to
> bytewide bus interface 1280.ps (370k).
> The chip has the following features:
> etc etc.
> * Tom Brown

I read through your description of this device and it sounds good, but I
didn't notice a dollar sign anywhere. Is it cost effective Tommy?

Also your lead for Gates Engineering in Singapore. Wasn't that 1 off
prices you quoted in a previous message. They didn't quite understand
where I was coming from. They work in 1000 off pcs. and $2000US minimum
orders.

Don McKenzie.          29 Ellesmere Cres., Tullamarine. 3043 Australia
ETI PIC Basic, BS1/2 & Alternatives.  18/28 PIC protos with RS-232/485
Promo Disk http://rasi.lr.ttu.ee/~sis/mirror/don/
finger TakeThisOuTdonmckEraseMEspamspam_OUTtbsa.com.au for more info.                    VISA-MC-BC
InfoFax 6 pages Inc cct: Voice then Fax +613 9338-2935 Password # 1111

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