PIC18F6621 some questions

Hans Wedemeyer · Joined: 15 Sep 2003 Posts: 226

Yet another new project looms on the horizon.
This time it will have to be something like the PIC18F6621 and I'm wondering if anyone has any direct experience with it ?

The data sheet claims programming time �1 Second programming time� is that true?

I�ll need to run Timer 1 with a 32KHz clock and Microchip are making a big deal about it in the data sheet.

Quote:
Timer1 can also be used to provide Real-Time Clock
(RTC) functionality to applications with only a minimal
addition of external components and code overhead.
end quote:

Yet I thought most other PIC18 and even PIC16 could do this!, why the special mention in this data sheet ?

Anyway my concern with timer 1 in this chip is :

Can Timer1 Interrupt be guaranteed to happen even if some other interrupt happens at the same time ?
or
Do I still need to poll the Timer 1 interrupt flag to ensure it has been serviced, or has Microchip solved the problem with multiple interrupts in this chip?

MYSTERY · Guest

Ib am sure the 18series you can set diffrent
levels of prioroties for different interrupts

look in the data sheet!

I hop this helps

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Well Hans, I guess it's too new. With these newer chips,
such as the 18F2320, etc., someone comes on here once
a week with some hidden problem. What do I do ?
I believe them.

I have a reputation, at least in my company, for my designs'
working. So I am appallingly, awfully, conservative.
I don't use these new PICs. I stick with something that I
know works and that won't embarrass me. I remember
what happened sometimes in my younger years, where I
would hear of failures in the field. I don't permit that to
happen now.

Haplo · Joined: 06 Sep 2003 Posts: 659 Location: Sydney, Australia

Wow. There's definitely a lesson to be learned here. I remember once you said you still use PCM3.148 for the final products.
I always risk the latest version. Once it almost got me, I just managed to stop the boards from going out the door (that happened when CCS released a version with a bank selection problem). But I still haven't learned my lesson. The question is, do I feel lucky? Very Happy

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Well, it's been awhile, so I have actually upgraded past 3.148. Smile

Haplo · Joined: 06 Sep 2003 Posts: 659 Location: Sydney, Australia

What version do use now? I still regard 3.169 to be the best version ever released.

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Right now, I'm using 3.184 for PCM. But that doesn't really mean
a lot, because we're not doing any PCM projects at the moment --
just PCH. But it does work OK for the little test programs that I
do when I answer questions on this board.

Hans Wedemeyer · Joined: 15 Sep 2003 Posts: 226

Yes I've been on the bleeding edge for many years....

PIC18C452 then PIC18F452 had a few problems, but latest silicon seem to be doing fine.

I simply have to move up and forwad, code space is the main reason, and I wishe Microchip would start making 16K and 32 K of RAM available.

As it happen the RTC feature I needs is not to difficult to do anyway. I just ran into the data sheet pushing it as if it's a new feature. Reading more does make it so, and I expect it will be useful some time in the future.
My version of the RTC really only has to run as long as the unit is powered, and has the luxory of GPS to synchronize. I'll be using RTC when GPS is not available ( tunnels etc)

Thanks for the input.... If I run into any "hidden" features I'll post them here.

COS (chnage of subject) EEPROM block write.... It's still on my ToDo list...
Montioring for busy as was suggested did not work...

hansw