I2c & Variable Size

[Archangel]

I'm using: PIC16F877A @ 20 MHz, an I2C RTC with PBP.

The story so far:

1. All works well - set the clock, read it and display the time.
2. I have a loop counter (VAR BYTE) in my software to do a job not connected with the RTC.
3. As long as the variable is a BYTE it works properly.
4. But if I make the loop counter a WORD - it will not increment (Variable = Variable + 1) fails to work. If I by-pass the RTC - it starts working!
5. The name of the loop counter is unique and not used in the RTC code.
6. I do need the variable to be word-sized.

Any ideas anyone?

Regards Bill Legge

Hi Bill,
Without having a firm grasp on your code . . . It works with BYTE variable, but not WORD . . . don't you have to split the word into highbyte and lowbyte to use it?
ahhh: not : that : i: could: read: it: Looks like skimask said that already!

[paul borgmeier]

I have not studied your code but....

>>Time var byte[3] ' Holds months,days,hours,mins read from RTC

and then

>>Time[3] = Month

You are overwriting the LoopCounter LowByte here (see your LST file) - change the [3] to [4] in the VAR define.

[Bill Legge]

Thanks for your replies:

Skimask:
1. DEFINE OSC 20 was in caps in my code, I messed it up whilst trying to tidy up the post.
2. Colon after TimeSet. As above, another 'posting mistake on my part. Code was OK.
3. Don't use " or '. Point taken - I'll change the comments and try again.
4. Thanks for the code - I'll give it a go. What is HCM?

Joe S:
1. HighByte/LowByte split - agreed I could 'work around' the problem but it seems
important to me that I find out why a WORD won't increment around an I2C read.

Paul B:
1. I think the array size is OK; Time[3] has 4 elements: 0,1,2,3. I'll check with a bit of test code.

Thanks to you all

Regards Bill Legge

[paul borgmeier]

>>Paul B:
>>1. I think the array size is OK; Time[3] has 4 elements: 0,1,2,3. I'll check with a bit of test >>code.

Hi Bill,

Not OK- see your manual or your lst file

[Bill Legge]

Paul B,

Thanks - I agree. Time[3] would give me 3 elements 0,1,2.
I'll make the changes.

I've returned to electronics after a gap of 25 years and find my
main difficulty is with the easier bits that I think I already know
and don't bother to look them up - hence this sort of mistake.

Regards

Bill Legge

[SteveB]

Not just Time, but Dtime also needs to be dimensioned correctly.

Time var byte[4] ' Holds months,days,hours,mins read from RTC
Dtime var byte[4] ' Holds months,days,hours,mins in HEX format

SteveB

[Bill Legge]

Thanks, I've changed the arrays to the correct size and -IT WORKS.

Sorry to bang on about WORD/BYTE/I2C when I just got a variable format wrong.

regards

Bill Legge

[skimask]

Skimask:
4. Thanks for the code - I'll give it a go. What is HCM?
Regards Bill Legge

Somebody coined the phrase for me awhile back... the 'High Colonic Master'. I like to use colons in my coding to keep as much of it on the screen at one time, prevent as much vertical scrolling as I can. Most people hate it, but I'm not writing code for most people, I'm writing code for me, and the majority of what I post here (or modify), gets the same treatment 'cause I like it that way...
that's all, nothing much...

I totally missed the array variable dimensioning thing...oh well...