I2CWRITE problem

[Art]

Whether you use a word or byte address depends on the EEPROM device.
It's in the manual for I2CREAD.

[Gusse]

Address size depends on EEPROM size (see table)
PicBasic Manual I2C -part
(2 bytes = 1 word)

Manual is Your friend

BR,
-Gusse-

[MR2010]

whether you use a word or byte address depends on the eeprom device.
It's in the manual for i2cread.

yeah but when u use xxx var byte

for xxx = 0 to 255 it works
THE PROBLEM IS WHEN IT COUNT FROM 0 TO 1023 IN WORD VAR IT DOES SOMETHING WRONG IM OUT FOR JOB WILL TRY LATER TAKE CARE EVERYONES I KNOW U WILL FINDOUT


try it out

[Paul]

I have been reading this discussion with interest as I have had a similiar problem to yours.

What I tried to do was to write 32 words in a word array to a 24LC256. Initially my micro was the 18F452, but I have moved over to the 18F4680. Both devices gave the same problem. My line of code was:

DATA var WORD [31]
AA var WORD
I2WR var byte
I2ADDR var WORD

I2CWRITE PORTC.4, PORTC.3, I2WR, I2ADDR, [ STR DATA\32 ], I2C_ERR

I would then read the data back as single words:

I2CREAD PORTC.4, PORTC.3, I2RD, I2ADDR, [ AA ], I2C_ERR


When I read the data back, I would repeatedly read some correct data, a bunch of $FFFF, more correct data, then the data would appear to 'move' and would not be at the designated eprom address. All very strange, but whats more it was repeatable within locations of the device.

The device data sheet specifiies that it can read and write a page of 64 bytes, (32 words).

I over came the problem by writing each word in the word array individually, pausing 5 ms between each word write. Not the best solution but it work. This way wastes 160ms of processing time.

I am still trying to find a way to solve my problem as I really need to write the data block in one hit. I might try using the hardware I2C technique next as I2CWRITE ... [ STR DATA\32] didn't work for me.


Paul.

[Dave]

Paul, I notice that you have only declared 31 WORDS but you are loading the eeprom with 32 BYTES. You can only load individual BYTES into the eeprom even if they are in an array. You would be loading the LOWBYTE of each of the words in the DATA array into the eeprom. Even then, you have only declared 31 words and not 32.

Dave Purola,
N8NTA

[Paul]

Paul, I notice that you have only declared 31 WORDS but you are loading the eeprom with 32 BYTES. You can only load individual BYTES into the eeprom even if they are in an array. You would be loading the LOWBYTE of each of the words in the DATA array into the eeprom. Even then, you have only declared 31 words and not 32.

Dave Purola,
N8NTA

Hi Dave,

That is correct, the 1st element in the array, DATA[0], the second element DATA[1], the 32nd DATA[31].

The STR command counts the elements in an array, [ STR DATA\1] would send element DATA[0]. PBPro knows if I am using WORDS or BYTES and counts them appropriately.

In this section of the PBPro manual, it clearly states that WORD variable arrays can be sent.

Paul.

[Gusse]

Hi Dave,

That is correct, the 1st element in the array, DATA[0], the second element DATA[1], the 32nd DATA[31].

The STR command counts the elements in an array, [ STR DATA\1] would send element DATA[0]. PBPro knows if I am using WORDS or BYTES and counts them appropriately.

In this section of the PBPro manual, it clearly states that WORD variable arrays can be sent.

Paul.

Hi Paul,

Check from manual about Arrays

It is two different things:
- Number of elements (array; 1,2,3,... )
- Location of element (string; 0,1,2,... )

BR,
-Gusse-

[Art]

Just to elaborate on the problem,
The middle part of this video shows the function that writes to EEPROM.
The messages are short because I can only type about 15 letters before
the first one stuffs up.
Each letter requires 6 bytes because they are stored as mono bitmaps,
and there is some lead in space written with zeros.



Art.

[Paul]

Hi Paul,

Check from manual about Arrays

It is two different things:
- Number of elements (array; 1,2,3,... )
- Location of element (string; 0,1,2,... )

BR,
-Gusse-

I had read this section of the manual sometime ago, and have obviously forgotten. Thank you Gusse, Art and Dave. It is good to be corrected and shown your error. Even with the change in array declaration, my page write I2C routine still will not work and exhibit the previously described problem. I will look at the physical aspects of the design (hardware), failing that attempt the hardware I2C routine. I have found some examples of code in the forums.

Paul