Suggestions for 8k-32k 8 pin PDIP I2C EEPROM chips

Zoot

I'm currently using a 24LC32A 4k (bytes - 32kbit) I2C EEPROM in a BS2p40 project. I store music scores, LED display patterns, Emic text phrases, etc.

I'm out of room and want to change out the chip for something larger -- 8k-32k (bytes). I2C ready, and ideally, with the same pinouts.

Does anyone have suggestions and/or a Jameco or Digikey part number?

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When the going gets weird, the weird turn pro. -- HST

Forrest

Use a 24LC128 (16 KBytes) or a 24LC256 (32 KBytes). They're widely available Mouser, Digikey, etc - just search for these part numbers. Pinout is the same on all 24LCxxx parts. All of these chips have 3 address lines (A0, A1 and A2) so you can string up to 8 of these chips together.

Zoot

Perfect. Thanks, Forrest.

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When the going gets weird, the weird turn pro. -- HST

KatyBri

Zoot,

Could you post your code? I would like to see how your talking to a I2C ready EEPROM.

Thanks.

Zoot

Sure, but it's not my doing, so don't give me credit This is code based on examples from the PDF manual for the BS2p Development Board (which shipped with a 4k I2C EEPROM) and various examples at the forum. This relies on the I2CIN and I2COUT commands, which are available (someone correct me if I'm wrong) on the BS2p, BS2p40, BS2pe and BS2px. The Basic Stamp manual also has some examples listed under I2CIN and I2COUT.

EEaddr VAR Word
addrHi VAR EEaddr.HIGHBYTE
addrLo VAR EEaddr.LOWBYTE
ioByte VAR Byte
ioWord VAR Word
datHi ioWord.HIGHBYTE
datLo ioWord.LOWBYTE

'i2c
I2Cw                  CON     0         'r/w bit write
I2Cr                  CON     1         'r/w bit read
'i2c addresses
fourkee               CON     $A0       '24LC32A 4k EEPROM address
fourkeemax            CON     $FFF      '4095      'highest address in 4k chip


'set ioByte or ioWord to be your data to write, set EEaddr to memory address
'a warning -- it takes time to write data -- time your program accordingly

ioByte = $1A              'write a single byte
EEaddr = $010           'some address
GOSUB Put_fourkeeByte
PAUSE 3

ioWord = $1A1A              'write a word
EEaddr = EEaddr + 1  'to next address
GOSUB Put_fourkeeWord
PAUSE 3

EEaddr = $010     'read a byte
GOSUB Get_fourkeeByte
DEBUG "address: ", HEX4 EEaddr, ", data: ", IHEX2 ioByte

EEaddr = $011     'read a word
GOSUB Get_fourkeeWord
DEBUG "address: ", HEX4 EEaddr, ", data: ", IHEX4 ioWord

DO : LOOP

'etc.........


Get_fourkeeByte:        'parameters: fourkAddr in 4K eeprom; returns: ioByte
   I2CIN SDA, fourkee | I2Cr, addrHi\addrLo, [noparse][[/noparse]ioByte]        ' read it back
   'DEBUG IHEX4 fourkeeaddr, ":", DEC3 ioByte, CLREOL, CR            'otherwise, print EEaddr and data and play the note
   RETURN

Put_fourkeeByte:        'parameters: fourkAddr in 4K eeprom; ioByte = data to write
   I2COUT SDA, fourkee | I2Cw, addrHi\addrLo, [noparse][[/noparse]ioByte]
   RETURN

Get_fourkeeword:       'parameters: fourkAddr in 4K eeprom; returns: ioWord
   I2CIN SDA, fourkee | I2Cr, addrHi\addrLo, [noparse][[/noparse]datLo, datHi]        ' read it back
   RETURN

Put_fourkeeword:       'parameters: fourkAddr in 4K eeprom; ioWord = data
   I2COUT SDA, fourkee | I2Cw, addrHi\addrLo, [noparse][[/noparse]datLo, datHi]        ' read it back
   RETURN

But there's a million ways to do it depending on your program needs. I read/write Byte streams sometimes as shown below, but check the Pbasic Stamp manual for details -- when writing arrays, the write terminates if the byte is $00 so you can get burned if you need to write $00 as data in your stream...

EEaddr VAR Word
addrHi VAR EEaddr.HIGHBYTE
addrLo VAR EEaddr.LOWBYTE
buffer VAR Byte(8)   'this example is 8 bytes max read/write
j  VAR Nib  '= how many bytes to read, write


'i2c
I2Cw                  CON     0         'r/w bit write
I2Cr                  CON     1         'r/w bit read
'i2c addresses
fourkee               CON     $A0       '24LC32A 4k EEPROM address

'pause after writing byte stream would be critical, btw

Get_fourkeebytes:       'parameters: j = how many bytes, EEaddr = address in 4K eeprom; returns: buffer array
I2CIN SDA, fourkee | I2Cr, addrHi\addrLo, [noparse][[/noparse]STR buffer\j]        ' read 'em back
   RETURN

Put_fourkeebytes:       'parameters: j = how many bytes, EEaddr = address in 4K eeprom, buffer = data array
   I2COUT SDA, fourkee | I2Cw, addrHi\addrLo, [noparse][[/noparse]STR buffer\j]        ' read it back
   RETURN

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When the going gets weird, the weird turn pro. -- HST

Post Edited (Zoot) : 1/8/2007 4:59:58 AM GMT

KatyBri

Zoot,

Thanks very much for taking the time to post the code. It was very helpful.

abcdefg

Would that code work with this EEPROM IC?

http://www.sparkfun.com/datasheets/IC/24LC256.pdf

Also, is there code like this that will work with just the BS2 stamp?

Post Edited (abcdefg) : 1/29/2007 4:47:16 PM GMT

Zoot

Yes. The 24LC256 is basically the same, just more bytes. If you are writing multiple bytes at once just watch for "page wrap" on the 32 byte boundaries (i.e., you can't write multiple byes in one shot to addresses 30-36 as that would cross the page boundary at byte 32 -- you can only write multiple bytes to addresses in 32 byte chunks -- 0-31, 32-63, etc)

If you want to run I2C commands from a BS2, there are bit-bang subroutines (by Jon Williams I think) that will handle this (since I2C is not "native" on the BS2):

http://forums.parallax.com/showthread.php?p=466264

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When the going gets weird, the weird turn pro. -- HST