What about the larger 512k or 1024k versions?

hello,
Couple of things I would like to clear up before you guys go scratching your head like i did to get it working with arduino.
1. Pull up resistors NOT required.
2. Pins 4 & 5 are Analog pins NOT digital!
3. Dont forget to include Wire.begin() in void Setup() function.
4. try pastebin.com/f3a36644b code (thanks shinmai for the link! Saved me a ton!) and check for any output before you code your own!
Thanks and hope these tips help. Good luck on your projects.
-Alvin

I will not be using a full arduino board with this, I will instead be using a bare atting85 or 84 I read that the buffer length should be shortened due to smaller RAM size so I changed:

ifndef twi_h

define twi_h

#include <inttypes.h>

//#define ATMEGA8

#ifndef TWI_FREQ #define TWI_FREQ 100000L #endif

#ifndef TWI_BUFFER_LENGTH #define TWI_BUFFER_LENGTH 32 //note this is the value I changed

endif

#define TWI_READY 0 #define TWI_MRX 1 #define TWI_MTX 2 #define TWI_SRX 3 #define TWI_STX 4

void twi_init(void); void twi_setAddress(uint8_t); uint8_t twi_readFrom(uint8_t, uint8_t*, uint8_t, uint8_t); uint8_t twi_writeTo(uint8_t, uint8_t*, uint8_t, uint8_t, uint8_t); uint8_t twi_transmit(const uint8_t*, uint8_t); void twi_attachSlaveRxEvent( void ()(uint8_t, int) ); void twi_attachSlaveTxEvent( void (*)(void) ); void twi_reply(uint8_t); void twi_stop(void); void twi_releaseBus(void);

endif

To this:

ifndef twi_h

define twi_h

#include <inttypes.h>

//#define ATMEGA8

#ifndef TWI_FREQ #define TWI_FREQ 100000L #endif

#ifndef TWI_BUFFER_LENGTH #define TWI_BUFFER_LENGTH 6 //note this is what I changed it to

endif

#define TWI_READY 0 #define TWI_MRX 1 #define TWI_MTX 2 #define TWI_SRX 3 #define TWI_STX 4

void twi_init(void); void twi_setAddress(uint8_t); uint8_t twi_readFrom(uint8_t, uint8_t*, uint8_t, uint8_t); uint8_t twi_writeTo(uint8_t, uint8_t*, uint8_t, uint8_t, uint8_t); uint8_t twi_transmit(const uint8_t*, uint8_t); void twi_attachSlaveRxEvent( void ()(uint8_t, int) ); void twi_attachSlaveTxEvent( void (*)(void) ); void twi_reply(uint8_t); void twi_stop(void); void twi_releaseBus(void);

endif

Should this small edit make this compatible with the attiny? The file changed is located in arduino\libraries\wire\utility/twi (header file) I kept a copy of the original in case this has messed anything up.

http://www.hobbytronics.co.uk/arduino-external-eeprom is also a nice tutorial in english and I'm writing one in my arduino book; http://cprogrammingforarduino.com

Love the chip, has a few quirks. The biggest is the 'page wrap', where if you overwrite the end of a 'page' in memory on the chip, it will overwrite the data at the beginning of that 'page'.
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1280095224

Nice ic, it helps a lot managing lot of data, and you can configure the i2c addr so you can use 8 of these in the same bus.
Best chip to controle my bitmaps for the nokia lcd with the arduino.

Great little ic, got it working with my basic stamp in no time. Works well for data logging.

Just an FYI...searching for 24LC256 shows no results, might want to update the search index...unless you have a policy to not list chips directly :)

I don't know if this is just me, or if I did something wrong, but I am unable to write more than 30 bytes to a page at a time, like this:

void formatEEPROM(int deviceaddress) {
    for (int p = 0; p < 1067; p++) {
        Wire.beginTransmission(deviceaddress);
        Wire.write((int)((p*30) >> 8));   // MSB
        Wire.write((int)((p*30) & 0xFF)); // LSB

        for (int i = 0; i < 30; i++) {
            Wire.write(0x00);
        }
        Wire.endTransmission();

        delay(5);
    }
}

If I try to write 32 bytes at a time and print the first 64 bytes, gaps appear on bytes 31, 32, 63, and 64. Does anyone know what I did wrong?

For anyone who thinks these are cheap here, they are 44 cents apiece over at Newark/element14... just sayin'

This product should include the word "memory" somewhere in the product description. Not for those of us reading it, but for those trying to find it. If you search for "memory", this doesn't show up at all. Product 301 has the same problem.

So, just to make sure, this chip has 256,000 places it can store a number in the form 0bXXXXXXXX ?

I wrote a .Net Micro Framework that I've confirmed works with the 512 and 1024 bit versions of this chip, as far as I can tell (I only looked quickly) this uses the same protocol. All of that is to say that my driver should work for this part too;

If you're having trouble with this IC, check out this tutorial.

Question - I've heard that these things will 'page wrap' around to the beginning of the page if you try and write too much data to 'em. If you write it, like, one bit at a time, will it still wrap around to the next page? Or will it go onto the next one? Thanks!

Example : http://lusorobotica.com/index.php/topic,461.msg2738.html

if eeaddress was 1101 1101 1100 0111

eeaddress >> 8 = 0000 0000 1101 1101 and wire.send() which sends bytes would truncate it to 1101 1101 which is perfect. its sent the high byte. but i dont understand this. eeaddress & 0xFF = 1101 1101 0000 0000 so wire.send() would send 0000 0000 which fails to send the low byte. is the code wrong in the exmaple?

Confused about the page write... note on page 9 says that pages start at integer multiples of the page size (64) and end at integer multiples of the page size - 1 (63). So the pages would be: 1st page starts at 0, ends at 63 2nd page starts at 64, ends at 126? 126 is a multiple of 63... then the third page would start at 64*2 = 128? what happened to address 127? Anyone from sparkfun know?

Awesome!

Is there a limitation in number of write cycles as it is for internal EEPORMs on Arduino boards ?

Nice looking chip... cheap, too! Note that it is only 32kB, but you can put a few of these on an I2C bus.

Unfortunately, I can't seem to get to RyanD's write-up anymore, but it was a good one. Here is a slight modification of his code. These are great little storage devices.
https://sites.google.com/site/measuringstuff/data-storage-retrieval#TOC-Storing-Stuff-To-External-EEPROM-24

Have a ZIF socket on your led matrix game board and have a few different games on each memory chip

windows app. link ends up with a corrupt rar file, would've been nice to try it...

Any chance that you guys plan to bring this in an SOIC pinout?

no matter what i try i cant seem to get these eeproms to work. i followed the tutorial for my arduino. hooked everything up (1->4&7 to gnd,8 to 5v,4&5 to the i2c pins)
yet i cant receive any data. ive folowed the code,tried other eeproms(in case of a broken one),other codes on the net,various pull-up resistors,various device adresses and yet it wont work. am i doing something wrong or is there something wrong with the wire lib?
im using the latest arduino software(0017).
any help would be very appreciated.