Post by thread:NVM's, I'm a little bit in the dark here !

Can anyone help me on my way with NVM's ?? I have to read out the two pages of an NVM --> X24C04 . This particular NVM has only two pages of 256 bytes, each with its own slave address. These slave addresses for the pages are : A0 and A2 --> Why do they differ by two ?? I know it has something to do with reading and writing these NVM pages. When you want to write to the first page, you write to adres A0. But, when you want to read from the first page, you have to read from adres A1. I really don't get this. Anyone ?? Glenn Goovaerts

The I2C standard uses the least significant bit of the slave address (i.e. A0) as a flag to tell the slave device whether you want to read or write. It was a simple way to implement the read write bit, but had the side effect of reducing the maximum number of possible slave addresses to 127. Cheers Mike Rigby-Jones > {Original Message removed}

without looking at the datasheet or knowing the chip, my guess would be that in the cirquit you have there is no read write line and that the address line a0 is used as such a1 probably does the bank 0/1 select Peter {Quote hidden}> Can anyone help me on my way with NVM's ?? I have to read out the > two pages > of an NVM --> X24C04 . This particular NVM has only two pages of > 256 bytes, > each with its own slave address. These slave addresses for the pages are : > > A0 and A2 --> Why do they differ by two ?? > > I know it has something to do with reading and writing these NVM pages. > > When you want to write to the first page, you write to adres A0. > But, when you want to read from the first page, you have to read > from adres > A1

> Van: Goovaerts <spam_OUTgoofy1TakeThisOuTGLO.BE> > Aan: .....PICLISTKILLspam@spam@MITVMA.MIT.EDU > Onderwerp: NVM's, I'm a little bit in the dark here ! > Datum: woensdag 18 augustus 1999 19:24 > > Can anyone help me on my way with NVM's ?? I have to read out the two pages > of an NVM --> X24C04 . This particular NVM has only two pages of 256 bytes, > each with its own slave address. These slave addresses for the pages are : > > A0 and A2 --> Why do they differ by two ?? Hello Glen, First, it's not A0 _and_ A2, but A0 _thru_ A2. Which means adress-lines A0, A1 and A2. Those together form a 3-bit adress, resulting in 8 possible page-adresses. The first byte send to the 24cXX memory (after the start-signal) is made up like this: 1010AAAD . Where AAA is the adress equal to the adress set on pin's 1 thru 3 of the IC, and "D" is the direction, or Read/Write bit. Greetz, Rudy Wieser