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SparWeb
22-05-2009, 20:09
Hi,

Looking at the AXE111 EEPROM memory board for the datalogger:

http://www.rev-ed.co.uk/images/full/axe111.jpg

One connector is the i2c connection to the AXE110 datalogger, and a question does come to mind - what's the other connector for? Can I put another memory board on there and use a different address to store data there? :) Would that address just be an increment higher than the first board's address?

Thanks,
Steven

tiscando
22-05-2009, 21:02
The axe110 datasheet on sections 9 and 10 implies that 'the other' connector would connect to the first 5 pins of PL1 connector of the speech synthesizer, like how it connects to the datalogger board without the axe111.

Obviously, multiple axe111s cannot be stacked because all the possible i2c addresses for the eeproms are used by the module, and stacking them will cause unpredictable behaviour (I have an i 2 c that the i2c addresses would conflict).

SparWeb
22-05-2009, 23:05
Hi!

The i2c address of the speech module is "$c4". Not a conflict with the EEPROM address, which is normally "%1010dddx". So if they can be connected in series, why can't another i2c device, such as a second EEPROM, also be connected in series with the first one?

Can a second board respond to a different address, such as "%1110dddx"? (That is just a number I made up as an example) Can the hardware be configured, or can the software be so programmed, that a different address can be used for i2c devices other than the clock and speech modules?


i2cslave $c4, i2cfast, i2cbyte 'speech synth, as per datasheet
i2cslave %11010000, i2cslow, i2cbyte 'clock address as per datasheet
i2cslave %10100000, i2cslow, i2cbyte 'EEPROM chip 1 as per datasheet
i2cslave %10100010, i2cslow, i2cbyte 'EEPROM chip 2 as per datasheet
...
i2cslave %10101110, i2cslow, i2cbyte 'EEPROM chip 8 as per datasheet

...then what...

i2cslave %11100000, i2cslow, i2cbyte 'some other EEPROM address....


Another way to phrase my question is "what do the first 4 digits of the EEPROM address mean?"

BCJKiwi
22-05-2009, 23:23
They are usually hard coded in the device and tend to relate to the class of device - i.e.

The bottom line is that only bits 321 are changeable on the typical eeproms (hence Tiscando's comment "all the possible i2c addresses for the eeproms are used by the module").

If you want more storage, go to bigger eeproms, or, search out different eeproms that use different address ranges, or set up a switching system so one set can be turned off and the other turned on - there have been previous posts discussing this option.

westaust55
23-05-2009, 03:46
Hi,

Looking at the AXE111 EEPROM memory board for the datalogger:


One connector is the i2c connection to the AXE110 datalogger, and a question does come to mind - what's the other connector for? Can I put another memory board on there and use a different address to store data there? :) Would that address just be an increment higher than the first board's address?

Thanks,
Steven

The second connector is basically just a pass through for any other i2c boards.
Note that 1 of the 5 pins to the AXE110 datalogger is intended as a Write Protect control for the EEPROMs on the AXE111 memory board.

In my case, I have a small protoboard with a DS1338 RTC connected to the second AXE111 conenctor. (The DS1338 is electrically identical to the DS1307 but can use i2cFAST as it operates with comms up to 400kHz)

NOTE that with respect to EEPROM's, if you have a smaller EEPROM such as the 24LC16 (or even a FM24C15 F-RAM) on the Datalogger in an i2c network in general, then because EEPROMS and even F-RAM's all have the same i2c chip type ID then you can only have one 24LC16 or FM24C16 AND NO other memory chip on the i2c bus.
The larger memory chips do impliment the addressing and thus up to a total of 8 memory chips (combination of EEPROM and F-RAM) can be conencted to the i2c bus.

MFB
23-05-2009, 09:02
How much memory do you need? You can access 1Mbyte by switching between two identically address banks of four 24FC1025 EEPROMS (8 chips total), by using an analog multiplexer to share the I2C bus.

tiscando
23-05-2009, 09:03
How about a FLASH memory module or IC - huge memory space per chip...

SparWeb
25-05-2009, 19:57
Thanks for all of your replies.
Wow I didn't know you could get a 24LC1024 - and I couldn't have come up with the analog multiplexer idea on my own. I'm finally getting some of the terminology straight, making my google searches more productive. Finally found Atmel and Michrochip websites and some info that I can peruse. Plenty of possibilities if I every do need to take on expanding the memory.

MFB
25-05-2009, 21:16
I didn't come up with the analog multiplexer idea on my own either. It was triggered by a Maxim application note on the MAX 235 single-rail multiplexer.