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'flash mem'
1999\07\16@164000 by mF6aWYgZ/xuZPzn?=

part 0 1082 bytes
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<DIV>&nbsp;</DIV>
<DIV>
<DIV><FONT color=#000000 face=Arial size=2>Hi Everybody,</FONT></DIV>
<DIV>&nbsp;</DIV>
<DIV><FONT color=#000000 face=Arial size=2>I need (28F010 SMD) or (29ee010 SMD)
flash type IC where can I buy from internet </FONT><FONT face=Arial size=2>is
there any body having Idea.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT>&nbsp;</DIV>
<DIV><FONT color=#000000 face=Arial size=2>&nbsp;&nbsp;&nbsp; Thank
you</FONT></DIV></DIV>
<DIV>&nbsp;</DIV>
<DIV><FONT color=#000000 face=Arial size=2>Best Regards</FONT></DIV>
<DIV><FONT color=#000000 face=Arial size=2>Nazif
Gunduc<BR></FONT></DIV></BODY></HTML>

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1999\07\16@200244 by Mark Willis

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Insight, http://www.ikn.com/ (Only shows the LV part in DIP though.)
Newark, http://www.newark.com/, $4.07 each
Digi-Key, http://www.digikey.com/, page 199 there, $4, PLCC part (150nS)

AMD and Atmel seem to be common on this part <G>

 Mark

{Quote hidden}


'flash mem'
1999\12\06@080650 by HJ Simpson
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Hi people,
Is there a flash memory (if that's the correct description) chip of some
sort, that I can write a few bytes (6 or so) to it from a 16F84, before
switching off, then read the data back in as a variable a few days or
weeks later, when it's all switched back on again?
I can't see any info where one can write data to the flash mem in the
PIC - I guess that area is program only.
Any pointers would be a big help.
Regards to all
Howard

1999\12\06@082719 by Jinx

face picon face
Hi, the F84 has non-volatile EEPROM bytes you can store variables
in that will hold the info (for up to 100 years) when the power is off. An
example of simple code to read/write to this memory is in the databook
or at various sites, including Microchip's. I don't think you will have any
lack of response from fellow PIClisters about how to program them or
pitfalls to look out for.

External EEPROM chips, usually 8-pin, are common. Parts such as the
24Lxx, 24LCxx, 93Cxx series, are easily obtainable and cheap. They
range in size from 256 bytes (or smaller) to 64k or larger. Microchip has
several application notes (documents of sample code routines) about
interfacing to external EEPROMs. The 8-pin devices are serial chips,
ie they require only a two-wire connection (clock and data).

If you really want to use FLASH, larger pin-count parallel chips such as
29C010 (128k  x 8) or 5V electrically erasable EPROMs are around,
but probably more expensive than the corresponding serial EEPROMs.
They also require more board space and addressing hardware.

If you take a wander through Microchip's site  http://www.microchip.com you'll
find all the information you need.

Jinx

1999\12\06@142352 by André Labelle

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Check out the PIC16F87X devices.  You can read and write the program
memory flash.  Also there are chunks of 8bit data EEPROM.  Here are some
routines to give you an idea.
-Andre
                                 char eeprom_r(char near * ptr @ EEADR)
0086                              {
000E 1283    BCF    STATUS,RP0
000F 1703    BSF    STATUS,RP1
0010 008D    MOVWF  0D
0011 1683    BSF    STATUS,RP0            EECON1.RD=1;
0012 140C    BSF    0C,0
0013 1283    BCF    STATUS,RP0            return(EEDATA);
0014 080C    MOVF   0C,W
0015 0008    RETURN
                                 }

                                 void eeprom_w(char near * ptr @
EEADR,char value @ EEDATA)
0086 0086                         {
0016 1283    BCF    STATUS,RP0
0017 1703    BSF    STATUS,RP1
0018 008C    MOVWF  0C
0019 0804    MOVF   FSR,W
001A 008D    MOVWF  0D
001B 1303    BCF    STATUS,RP1            PIR2.EEIF=0; /* clear the
'write complete' flag */
001C 120D    BCF    0D,4
001D 1683    BSF    STATUS,RP0            EECON1.WREN=1;
001E 1703    BSF    STATUS,RP1
001F 150C    BSF    0C,2
0020 3055    MOVLW  55h                   EECON2=0x55;
0021 008D    MOVWF  0D
0022 30AA    MOVLW  AAh                   EECON2=0xAA;
0023 008D    MOVWF  0D
0024 148C    BSF    0C,1                  EECON1.WR=1;
0025 110C    BCF    0C,2                  EECON1.WREN=0;
0026 1283    BCF    STATUS,RP0            while(!PIR2.EEIF); /* wait for
write complete */
0027 1303    BCF    STATUS,RP1
0028 1E0D    BTFSS  0D,4
0029 2826    GOTO   0026h
002A 0008    RETURN               }

HJ Simpson wrote:
{Quote hidden}

1999\12\06@184034 by John Feibusch

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I've been working on a project that uses an Atmel AT45D081 flash memory chip con
nected to a PIC 16C67; it seems to work well. It sounds a bit large for your app
lication; the flash holds 1 megabyte: 4096 pages of 264 bytes each. But they do
have smaller devices.

It connects to the PIC via the syncronous serial port; I don't know if the 16F84
has one of those.

> Hi people,
> Is there a flash memory (if that's the correct description) chip of some
> sort, that I can write a few bytes (6 or so) to it from a 16F84, before
> switching off, then read the data back in as a variable a few days or
> weeks later, when it's all switched back on again?


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1999\12\06@191449 by Gennette Bruce

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This is built in to the 16F84 -  as 64 bytes of EEPROM.

There are 3 special registers, some flags and a couple of special codes to
pass around for sending bytes to/from the EEPROM.  Microchip has examples on
their site which you must follow exactly (about 8 lines for a write, 6 lines
for a read).

This EEPROM is not as versatile as flash RAM; its slower and can only stand
10,000 or so writes, with billions of reads (at least several orders of
magnitude less cycles than RAM).  All the following numbers are VERY
conservative, but better safe than sorry.

External EEPROM chips have the same limitations, but being larger the
programer can extend the apparent write cycles. You may choose to write to
each byte say a conservative 2,048 times, then change to other bytes before
these fail.  Using just an 8 byte block on a 2K chip at 2,048 write cycles
per block gives 524,288 writes.

You need to use a few bytes to track the number of writes and point to the
current active block. Hint - consecutively read from the first byte of the
counter area until a whole byte is found to be 0. The big endian compound
digital total is the grand total of the number of writes carried out, the
current block in use is INT(total/2048).  Increment total whenever a block
is written.

Bye.

> {Original Message removed}

1999\12\07@061436 by Caisson

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> Van: HJ Simpson <spam_OUTbrahTakeThisOuTspamULTRA.NET.AU>
> Aan: .....PICLISTKILLspamspam@spam@MITVMA.MIT.EDU
> Onderwerp: flash mem
> Datum: dinsdag 7 december 1999 8:05
>
> Hi people,
> Is there a flash memory (if that's the correct description) chip of some
> sort, that I can write a few bytes (6 or so) to it from a 16F84, before
> switching off, then read the data back in as a variable a few days or
> weeks later, when it's all switched back on again?
> I can't see any info where one can write data to the flash mem in the
> PIC - I guess that area is program only.

The PIC16x84 has got 0x40 bytes of EEPROM at adress 0x2100.  If you want to
define data at Assemble-time, here is where you will have to put it.

My Data-sheet (DS30445B) has got the description of how to Read/Write the
EEPROM at page 11-31.  I think I even have got some example floating around
somewhere (from the MicroChip CD ...)

If you want I can send you the .PDF-file / Examples by private E-Mail ..

Regards,
 Rudy Wieser

1999\12\07@210945 by Donald L Burdette

picon face
Several other ideas -

In addition to the 16F84 and 16F87x family, Microchip makes 12CExx parts
with 16 bytes of EEPROM internal. They're great if you can use 8-pin
parts.  I don't know if they're available yet, but I think there were
some bigger parts planned.

Dallas Semiconductor (http://www.dalsemi.com) makes 3-pin serial EEPROM devices
that interface through only 1 bi-directional pin.  They're a little more
expensive and more software work, but great if you are limited on pin
count or have to put several peripherals on a single bus.  You can put
any number of devices on the 1-wire bus.  They make A/D's, temperature
sensors, real-time clocks, memory, analog switches, etc.

External FLASH memory is usually parallel, not serial, although there
were some serial parts available several years ago.  Flash is the
economical choice when you need large memories.  We use a 512 K-byte part
that's around US$4.00, and it's a small one.  Larger ones are less
expensive per bit.

The least expensive external part you can use to get a few bytes is
probably the 24C00 or one of its siblings (24LC00, 24LV00, etc).  Use the
one that has the right voltage/power/write-cycle specs for your
application.  Some of these parts are less than $0.25 in quantity, less
then $0.40 in single pieces.

Someone mentioned that these parts go up to 64K or higher.  I know of
256K parts available from M'Chip, but  AFAIK, all serial memories and
most parallel memories are now advertised in bits, not bytes, so that
256K part is 256K bits, or 32K bytes, and that's the largest yet
available.  If anyone knows otherwise, please let me know, because we use
a lot of serial EE, and we stack them in groups of 4 or 8 to get larger
memories!

Don

1999\12\08@085434 by Dr. Imre Bartfai

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On Tue, 7 Dec 1999, Gennette Bruce wrote:

> This is built in to the 16F84 -  as 64 bytes of EEPROM.
>
> There are 3 special registers, some flags and a couple of special codes to
> pass around for sending bytes to/from the EEPROM.  Microchip has examples on
> their site which you must follow exactly (about 8 lines for a write, 6 lines
> for a read).

Correct.
>
> This EEPROM is not as versatile as flash RAM; its slower and can only stand
> 10,000 or so writes, with billions of reads (at least several orders of
> magnitude less cycles than RAM).  All the following numbers are VERY
> conservative, but better safe than sorry.
>
Nope. Mchip guarantees a million of write/read cycle or so. The limited
number certifies the program flash memory which is completely different
from that data EEPROM
>
> External EEPROM chips have the same limitations, but being larger the
> programer can extend the apparent write cycles. You may choose to write to
> each byte say a conservative 2,048 times, then change to other bytes before
> these fail.  Using just an 8 byte block on a 2K chip at 2,048 write cycles
> per block gives 524,288 writes.

I am not sure whether this limitations are valid for Mchip products. I
guess no. See ANxxx referring to the topic 'endurance'.

Regards,

Imre

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