I2CWRITE not writing anything on PIC18F45K80

[tumbleweed]

Your arrays are declared as 'var byte[16]'

topline var byte [16]
botline var byte [16]

That means a valid array index is from 0-15

This code here will fail when x=15

if X<=15  then
Y=(botline[x]-48)*8
Z=(botline[x+1]-48)*8 'READ  INTO VARIABLE AS TWINS

Z will try and access botline[x+1] = botline[16], which is invalid

[CuriousOne]

X is being incremented in steps of 2, so it will never be 15.
I even modified code so that X will never exceed 14 - issue is still here, but there is some logic in it.

I tried to add code in loop and look at output.
it changes in the following way based on loop step:

012345 789ABCDEF
0123456789 BCDEF
012345678 ABCDEF
01234567 9ABCDE

[CuriousOne]

Did a test with various size of arrays.
If both arrays do not exceed 24 bytes total, then everything is fine. As they exceed 24 bytes, issues start to appear.

[tumbleweed]

Fair enough, but what about this when x >= 16

if topline[x]=32 or botline[x]=32 then a=0
if topline[x+1]=32 or botline[x+1]=32 then b=0 'blanker

[CuriousOne]

I don't see any relation
I modified code and X now changes from 0 to 14 - still same issue.

[tumbleweed]

You've been using x, y, and z to get values to set a and b.
You've been shoving invalid data out to the lcd and wondering why the display is wrong.

It's probably still wrong.

[CuriousOne]

LOL.
I'm trying to explain that if I add one extra array definition, another array gets screwed. How this is related to LCD?
I just wrote another code, which simply reads values of array and writes data on 1602LCD.
Issue still exists - data in array gets damaged, if total array length exceeds 24 bytes.

[tumbleweed]

I just did this with an 18F45K80

' device = 18F45K80

topline var byte [16]  'top part of the screen array
botline var byte [16] 'bottom part of screen

ix var byte
ct var byte
cb var byte

' clear arrays
for ix = 0 to 15
    topline[ix] = 0
    botline[ix] = 0
next ix

' read array data
arraywrite topline,["0123456789ABCDEF"]
arraywrite botline,["0123456789ABCDEF"]

ix = 0

'read array char by char
for ix = 0 to 15
    ct = topline[ix]
    cb = botline[ix]
next ix

ix = 0

When it gets to the end, topline and botline arrays are exactly as specified... each is 16 chars "0"-"F"
Reading the arrays byte by byte also does as expected.
I even added a third array of 16 chars... works too.

Your problem is elsewhere... not with the arrays themselves.