Searching \ for '[PIC]:SRAM' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/microchip/memory.htm?key=sram
Search entire site for: 'SRAM'.

Exact match. Not showing close matches.
PICList Thread
'[PIC]:SRAM'
2002\05\15@210702 by Goring, Steve

flavicon
face
Hi List ..

I have been given a number of static ram 6264 chips ( does it sound like
I know what I am talking about ?? )

I have never used SRAM before and would like to know would it be worth
using, if so can I use it with a Pic and lastly if yes - could someone point
me in the direction of any code snippets.

My application is for data logging in a home built weather station - I have
pioneered my 232 link to my PC but that means leaving it on all the time.
My preferred option is to log to an amount of memory and then download
the data at specific time intervals.

Is the SRAM I have suitable or should I investigate I2C ( which would have
been my next option had I not been given these chips ).

Thanks in advance ...

Steve





**********************************************************************
Information in this email is confidential and may be privileged.
It is intended for the addressee only. If you have received it in error,
please notify the sender immediately and delete it from your system.
You should not otherwise copy it, retransmit it or use or disclose its
contents to anyone.
Thank you for your co-operation.
**********************************************************************

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email spam_OUTlistservTakeThisOuTspammitvma.mit.edu with SET PICList DIGEST in the body


2002\05\15@214835 by Tony Nixon

flavicon
picon face
"Goring, Steve" wrote:
{Quote hidden}

You will need to interface 13 address lines, 8 data IO lines, plus the
OE and WE pins for a total of 23 connections which means using a 40 pin
PIC such as 16F877.

Read
Place the address data on the address bus A0..A12
WE = High
OE = Low
Data appears on D0..D7
Read data
OE = High

Write
Place the address data on the address bus A0..A12
Place data on D0..D7
OE = High
WE = Low
WE = High

You will need to check the data sheet for your device for exact timing
requirements.

You could use PORTB for the data bus and enable the pullups.
PORTD for the lower address A0..A7
PORTC 0..4 for upper address A8..A12
PORTE 0 for WE
PORTE 1 for OE
Tie CE1 low
Tie CE2 high

This is only 8K x 8 and volatile, but if you use something like a
24LC256 serial I2C EEPROM it will only gobble up 2 IO pins and give you
32K x 8 non volatile storage.



--
Best regards

Tony

mICros
http://www.bubblesoftonline.com
.....salesKILLspamspam@spam@bubblesoftonline.com

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listservspamKILLspammitvma.mit.edu with SET PICList DIGEST in the body


2002\05\15@220724 by David V. Fansler

picon face
Steve the 6264 would probably be an 8k memory chip.  This means it would
have 13 address lines, 8 data lines, a chip select, and write line and a
read line for a total of 24 lines.  This would tie up 3 8 bit ports of a
PIC.  While the 6264 was easy to use with a RCA1800 uP, I think that I2C
would be more efficient (from a hardware standpoint.)


David V. Fansler
S/V Annabelle
.....DFanslerKILLspamspam.....MindSpring.com
http://www.dv-fansler.com

{Original Message removed}

2002\05\15@221630 by Jinx

face picon face
You can use a 4040 as an address driver for most of the RAM,
which needs just clock and reset. Random access will be
laborious as the 4040 is sequential, but if you just want to dump
the contents into a PC then you'd be OK. A 4040 has 12 o/p
lines, and you'll need to supply the 13th from the PIC. Pull the
RAM's /CS high with a 1k resistor for power-down and pull it
low with a BS170 when you want to access the RAM. CMOS
RAMs will use a fraction of a uA when powered down, but
other types may use a few uA

To read/write data is easy, assuming you've met the conditions
in the truth table for /CS1 CS2 /OE and /WE. To read just set
the address, put a high on /WE and CS2, a low on /OE and /CS1
(making sure you've got the PIC or PC as an input) and then just
pick up the data off the buss. To write, pretty much the same
except /OE is high and you flick /WE low for the specified time

Note that it's immaterial how you connect the address lines.
A0 of the driver does not have to go to A0 of the RAM and so
on. Each location has a unique address

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email EraseMElistservspam_OUTspamTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body


2002\05\16@025417 by Mircea Chiriciuc

flavicon
face
Hi Steve!

I also want to buid a home wheather station. Nice to find you. I would
suggest to use an I2C memory chip because it uses less pins and it non
volatile as the SRAM. You can download the logged data any time after
logging and a power failure won't mean loosing your data.

I can provide you with code for I2C and many other things I think. Don't
hesitate to conntact me.

Best regards,
Mircea Chiriciuc
EMCO INVEST

{Original Message removed}

2002\05\16@075140 by Mark J. Dulcey

flavicon
face
> "Goring, Steve" wrote:

>> I have never used SRAM before and would like to know would it be worth
>> using, if so can I use it with a Pic and lastly if yes - could someone point
>> me in the direction of any code snippets.
>>
>> My application is for data logging in a home built weather station - I have
>> pioneered my 232 link to my PC but that means leaving it on all the time.
>> My preferred option is to log to an amount of memory and then download
>> the data at specific time intervals.

Tony Nixon wrote:
>
> This is only 8K x 8 and volatile, but if you use something like a
> 24LC256 serial I2C EEPROM it will only gobble up 2 IO pins and give you
> 32K x 8 non volatile storage.

On the other hand, the interface to the SRAM will be considerably faster
than an interface to a serial EEPROM, so there are applications where it
would be the right solution. Speed doesn't sound essential for the
application described by Steve, so it's probably better to just skip the
SRAM and look for a suitable serial chip.

If your system is already using a large PIC and you don't have enough
I/O pins, you could also use an external latch or two to reduce the
number of I/O pins needed on the PIC. You'd still need more pins than
with the serial chip, though. If you're not already using a large PIC,
it's usually simpler and cheaper to just step up to a bigger one than to
get involved with external glue.

--
http://www.piclist.com hint: To leave the PICList
piclist-unsubscribe-requestspamspam_OUTmitvma.mit.edu


2002\05\16@114906 by Herbert Graf

flavicon
face
SRAM is volatile, you loose power, you loose all the data collected. For
something like your application I personally recommend going with EEPROM,
that way power loses don't affect you. There are several I2C EEPROMs out
there (made vby Microchip as well) that would be perfect for your
application. TTYL

> {Original Message removed}

More... (looser matching)
- Last day of these posts
- In 2002 , 2003 only
- Today
- New search...