Timer0 problem

ecoology · Joined: 07 Nov 2006 Posts: 340 Location: USA - California

This is probably going to be one of those "you're a dummy questions."

I want to use timer0 as an interrupt timer. This should be simple. I am using the mega324, BASCOM 1.11.9.2

AdrianJ · Joined: 16 Jan 2006 Posts: 2483 Location: Queensland

You dont have a label for Begin, which might do a reset.

I would do it more like this: ( untested code ! )

Visovian · Joined: 31 Oct 2007 Posts: 584 Location: Czech

Hi,

ecoology · Joined: 07 Nov 2006 Posts: 340 Location: USA - California

Almost out of hair...
Fading fast!

I've tried the suggestions offered, plus a lot more. It seems nothing will cause the timer0 to time out and jump to the ISR. The code I currently have is:

DToolan · Posted: Tue Jul 22, 2008 5:16 pm Post subject:

** Removed **

ecoology · Joined: 07 Nov 2006 Posts: 340 Location: USA - California

Using this code exactly, which I agree with, does not work. something else is going on.
I am using the mega324, and I've gone through the data sheet, but I do not see anything different from other megas. The processor works correctly in all respects except this. Now wondering if I have a defective chip - the timer0 is just bad????
This is one of those - ITS GOTTA WORK issues, but it doesn't
I am going to build up another board and see if this is an isolated case.

ecoology · Joined: 07 Nov 2006 Posts: 340 Location: USA - California

This is an example of "don't beat your brains in!"
I spent two days trying to get a simple interrupt using timer0 to work.
I just changed over to timer1, and it works!
There is a defect in the chip - timer0 is non-functional. Everything else works, and timer1 works as advertised.
Thanks for the inputs. Seeing that I wasn't that far off track led me to look at the chip itself. They can fail. It wasn't a BASCOM issue at all.
Long Live BASCOM!

rileyesi · Joined: 19 Dec 2006 Posts: 398

Ecoology,

This may or may not help, but years ago I designed a board using the old 4433 chip. Out of sheer dumb (bad!) luck, I used three pins on port b to dirve a D to A converter. A while later, I used the same board on a different design that needed to use timer0. I could not get it to work no matter what I did.

Then, I read the data sheet more closely and found (to my horror) that you needed port b to be able to use the timer0! (or something like that. My memory is kinda fuzzy on the details. maybe because I blocked them out!)

I did not look at the data sheet for your chip. Maybe there is a similar problem??

Hope this helps.

Pete

ecoology · Joined: 07 Nov 2006 Posts: 340 Location: USA - California

I'll take a look, but I don't recall seeing anything like that. These chips are so complex, that who knows? Anything is possible. All I know right now is that timer1 works perfectly, and timer0 is dead. out of a couple million transistor-equivalents, it only takes one failure to stop a function if not the whole chip.

rileyesi · Joined: 19 Dec 2006 Posts: 398

One other thought.

The following is a code snippet from one of the sample programs that came with BASCOM:

ecoology · Joined: 07 Nov 2006 Posts: 340 Location: USA - California

Interesting, but I am not using any config clock statments.
I am still in trouble because the timer1 is a 16 bit timer. Even with prescale = 1, I can't get a fast enough timout. Best I get is about 120 ms. I need a timout of about 20 ms.
Maybe a Config clock not so soft???

rileyesi · Joined: 19 Dec 2006 Posts: 398

I have a program that needs 50 ms loops and I simply use the WAITMS command. I could not get it to run using the TIMERs.

I'm not saying that it can't be done by someone smarter than me!

Good luck.

Pete

ecoology · Joined: 07 Nov 2006 Posts: 340 Location: USA - California

These timers should be simple to use. They were designed for interrupt operations, and the BASCOM commands were intended to use as int generators. we are not doing anything so complicated, why would the timers be such a pain?
Timer1 does work well, just not fast enough. its timer0 that seems to be a problem.
It seems like there is something in configuring the timer.
I've had other problems setting registers directly. I prefer to manipulate the registers so I know exactly what is going on, but that has pitfalls. i've sent a message to Mark, asking for clarification on how to handle the registers. Maybe the BASCOM command is not setting something for timer0?

AdrianJ · Joined: 16 Jan 2006 Posts: 2483 Location: Queensland

To get timer1 to have an 8 bit timeout period, just set its hi byte to &hff, and if course its low byte to 0. Be aware that you need to set the hi and lo bytes in the correct order - write the hi byte first. Bascom handles this correctly if you just do:
Timer1 = &hff00

You certainly seem to have problems with timer0, or maybe just that chip. I dont have that specific processor handy, but I certainly use timer0 with other processors ( AtMega64, 644, 16, 32 ) without problems.

ecoology · Joined: 07 Nov 2006 Posts: 340 Location: USA - California

Thank you, Adrian.
Yes, I am having far more than reasonable issues with timer0. Others have commented that they have had problems too, so I don't feel like the Lone Ranger, but it is frustrating to waste so much time on seemingly simple things.

I'll play with your suggestion.
George