External Eeprom - trying to store multiple variables

I am struggling with an eeprom 24lc256. I can read/write a one word variable to it. My test example below has the variable increasing in increments of 3 and being stored in sequential addresses. That worked OK. But what I'm struggling with is storing multiple variables.

This code worked OK:

Code:

DPIN var PORTD.4 ' I2C data pin CPIN var PORTD.5 ' I2C clock pin I2CAddress var Word 'Changed to WORD B1 var Byte B2 var Word Start Pause 500 debug 13,10,"Begin " B1 = 0 B2 = 0 Pause 1000 For I2CAddress = 0 To 600 step 2 ' Number of Steps equals number of bytes of data (so we don't overwrite) I2CWRITE DPIN,CPIN,$A0,I2CAddress,[B2] ' Write each location's address to itself Pause 10 ' Delay 10ms after each write B1 = B1 + 1 B2 = B2 + 3 Next I2CAddress mainloop: For I2CAddress = 0 To 600 step 2 ' Loop I2CREAD DPIN,CPIN,$A0,I2CAddress,[B2] ' Read 2 locations in a row debug 13,10, " Data ",Dec B2 Pause 10 Next I2CAddress debug 13,10,"END ",13,10 END

To store multiple variables I tried this: (Changed step 2 to Step 2 and added B1)

Code:

For I2CAddress = 0 To 600 step 3 ' Number of Steps equals number data bytes (so we don't overwrite) I2CWRITE DPIN,CPIN,$A0,I2CAddress,[B1,B2] ' Write to locations on Eeprom Pause 10 ' Delay 10ms after each write B1 = B1 + 1 B2 = B2 + 3 Next I2CAddress mainloop: For I2CAddress = 0 To 600 step 3 ' Loop I2CREAD DPIN,CPIN,$A0,I2CAddress,[B1,B2] ' Read 2 locations in a row debug 13,10, "Data 1 ", Dec B1," Data 2 ",Dec B2 Pause 10 Next I2CAddress

And I tried this: (Changed step 2 to step 3, added B1 with plus high byte/low byte)

Code:

For I2CAddress = 0 To 600 step 3 ' Number of Steps equals number data bytes (so we don't overwrite) I2CWRITE DPIN,CPIN,$A0,I2CAddress,[B1,B2.byte0,B2.byte1] ' Write to locations on Eeprom Pause 10 ' Delay 10ms after each write B1 = B1 + 1 B2 = B2 + 3 Next I2CAddress mainloop: For I2CAddress = 0 To 600 step 3 ' Loop I2CREAD DPIN,CPIN,$A0,I2CAddress,[B1,B2.byte0,B2.byte1] ' Read 2 locations in a row debug 13,10, "Data 1 ", Dec B1," Data 2 ",Dec B2 Pause 10 Next I2CAddress

It sort-of worked but there were some errors. Here's the output:

Code:

Data 1 0 Data 2 16128 <---- wrong! Data 1 1 Data 2 3 Data 1 2 Data 2 6 Data 1 3 Data 2 9 Data 1 4 Data 2 12 Data 1 5 Data 2 15 Data 1 6 Data 2 18 Data 1 7 Data 2 21 Data 1 8 Data 2 24 Data 1 9 Data 2 27 Data 1 10 Data 2 30 Data 1 11 Data 2 33 Data 1 12 Data 2 36 Data 1 13 Data 2 39 Data 1 14 Data 2 42 Data 1 15 Data 2 45 Data 1 16 Data 2 48 Data 1 17 Data 2 51 Data 1 18 Data 2 54 Data 1 19 Data 2 57 Data 1 20 Data 2 60 Data 1 21 Data 2 32352 <---- wrong! Data 1 22 Data 2 66 Data 1 23 Data 2 69

I am missing something... but what?
Thanks for your help.

You cannot write or read a word directly as you are trying to do. Split the word into two bytes (lowbyte + highbyte)

Code:

I2CWRITE DPIN,CPIN,$A0,I2CAddress,[B2.byte0,B2.byte1] ' Write each location's address to itself

same thing for I2CREAD.

Edited: Sorry I didn't read the whole post so I didn't see you have already splitted the word into two bytes. But the point remains You CANNOT handle the word as a single piece.

Al.

Hi,
i had same problem, i do not calc in the write command:
a = B1.highbyte
b = B1.lowbyte
I2CWRITE sda, scl, add, loc, [a,b]
Ralf

Thanks for the help.

I really am not sure what exactly is/was wrong. The only way for me to make it work is to write one byte on each I2CWRITE command. If I attempted to write more than one variable at a time there would be the occasional error in the written data. Maybe it's a wiring issue (although the mistakes were always at the same data points....?)

Here's what worked:

Code:

For x = 1 To 200 ' Number of Steps equals number of bytes of data (so we don't overwrite) I2CWRITE DPIN,CPIN,$A0,I2CAddress,[B1.highbyte] ' Write each location's address to itself I2CAddress = I2CAddress + 1 Pause 10 I2CWRITE DPIN,CPIN,$A0,I2CAddress,[B1.lowbyte] ' Write each location's address to itself I2CAddress = I2CAddress + 1 Pause 10 I2CWRITE DPIN,CPIN,$A0,I2CAddress,[B2.highbyte] ' Write each location's address to itself I2CAddress = I2CAddress + 1 pause 10 I2CWRITE DPIN,CPIN,$A0,I2CAddress,[B2.lowbyte] ' Write each location's address to itself I2CAddress = I2CAddress + 1 pause 10 I2CWRITE DPIN,CPIN,$A0,I2CAddress,[B3.highbyte] ' Write each location's address to itself I2CAddress = I2CAddress + 1 Pause 10 ' Delay 10ms after each write I2CWRITE DPIN,CPIN,$A0,I2CAddress,[B3.lowbyte] ' Write each location's address to itself I2CAddress = I2CAddress + 1 Pause 10 ' Delay 10ms after each write B1 = B1 + 1 B2 = B2 + 3 B3 = B3 + 5 pause 10 Next x

Quote:

Note: Page write operations are limited to writing
bytes within a single physical page,
regardless of the number of bytes actually
being written. Physical page boundaries
start at addresses that are integer
multiples of the page buffer size (or ‘page
size’) and end at addresses that are
integer multiples of [page size – 1]. If a
Page Write command attempts to write
across a physical page boundary, the
result is that the data wraps around to the
beginning of the current page (overwriting
data previously stored there), instead of
being written to the next page, as might be
expected. It is, therefore, necessary for the
application software to prevent page write
operations that would attempt to cross a
page boundary.

The above text comes from the device datasheet and is the answer to your problem.

Al.

Al,

You're exactly right. Thanks.

I was seeing data errors at specific intervals, specifically every multiple of 64. This explains it!

'Physical page boundaries start at addresses that are integer multiples of the page buffer size'