LockedI2C RAM

Post
Guest
Super Member
2005/02/28 11:43:46
Does anybody know some I2C RAM with great capacity (16K or 32K*8bits) In the Internet I could only find low capacity (512 bytes) I2C RAM. I do not want to waste pins of my P16F877a chip connecting a parallel RAM 62256. So I think that using a I2C could be a better solution.

Antonio Leite
nice
Super Member
RE: I2C RAM 2005/02/28 12:46:25
Hi Antonio,

RAMTRON offers 256kb nonvolatile FRAM. It's endurance is stated as 10 billion read/write operations.

http://www.ramtron.com/doc/Products/Products_detail.asp?ID=41&FamID=1

Best regards,
Bernd
luhan
Starting Member
RE: I2C RAM 2005/02/28 19:57:05
Hi,

I use Microchips 24LC512 with I2C protocol. They work just fine.

http://members.cox.net/berniekm
luhan
Starting Member
RE: I2C RAM 2005/02/28 19:58:17
......

The 24LC512 is 512k bits = 64k bytes.
kalpak
Super Member
RE: I2C RAM 2005/02/28 22:43:09
Dallas have some kinds of serial rams of large capacity and also a serial to parallel converter chip for the same purpose.
bob_barr
Super Member
RE: I2C RAM 2005/02/28 22:57:52
The 24LC512 is 512k bits = 64k bytes.

It's also an EEPROM device and not RAM.

Writing to EEPROM is significantly slower than writing data to RAM.
kalpak
Super Member
RE: I2C RAM 2005/03/01 00:41:57
And the number of operations are significantly lesser. FRAMs are a better choice.
luhan
Starting Member
RE: I2C RAM 2005/03/01 09:09:43
Hi,

My mistake, should have asked about the writing rate to the memory...

I looked up FRAMs, largest I found was 256 bytes - you can get close to that much inside some of the PICs. Are there any larger scale FRAMs? I could use some myself.
schen
Super Member
RE: I2C RAM 2005/03/01 09:25:53
FM24C256 is 32K bytes in size.
Ldanielrosa
Super Member
RE: I2C RAM 2005/03/01 13:46:46
I took a look at the link. I didn't have time to go searching for technical details, but the name made me wonder if this is a repeat of core memory. I wonder if it is susceptable to strong magnetic fields. Just the same, I plan to use a few.
nice
Super Member
RE: I2C RAM 2005/03/01 21:45:23
I wonder if it is susceptable to strong magnetic fields.

Excerpt of this PDF.
People commonly misunderstand the name
ferroelectric. To many, a name using the prefix
“ferro” seems to imply iron or magnetism. The word
ferroelectric also is confused with ferromagnetic. In
reality, ferroelectric memories use no iron or
magnetic principles. They are not susceptible to
external magnetic fields as they operate entirely using
electric fields just as conventional DRAMs.


Best regards,

Bernd
kalpak
Super Member
RE: I2C RAM 2005/03/02 02:10:21
I suspect the word ferro has been borrowed from the term ferromagnetic to imply remainence of effect after the removal of the field. Just as ferromagnetic material which remain magnetised after the removal of the magnetising field.
But I wonder if MRAM (magnetostricitive ram) are vulnerable to magnetic field?
nice
Super Member
RE: I2C RAM 2005/03/02 09:41:24
But I wonder if MRAM (magnetostricitive ram) are vulnerable to magnetic field?

Yes, it is. Take a look at Freescale's MR2A16A data sheet (link). The maximum magnetic field intensity at package surface is specified as 20oe (about 1600A/m).

Best regards,

Bernd
Guest
Super Member
RE: I2C RAM 2005/03/04 01:31:29
Hi Bernd and everyone

Thanks for your suggestions

In fact I have an 24LC256 eeprom in my i2c and a RTC 8583 from Philips port but as I will have to make a large number of updates in tables I have in memory, I will save the data on the eeprom and copy them to the FRAM so it will be faster and no stress on the number of updates.
Dallas has parallel battery backup memories, some with clock and alarm possibilities. I use to use DS1286 with 8051 processor that do not have I2c bus.

Thanks again
hqsystems
Super Member
RE: I2C RAM 2005/03/30 10:50:24
please explane the saving on the EEprom and then copy to The Fram.
Wy is that faster