Searching \ for 'FreeRTOS port to PIC18LF45K22 anyone?' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/microchip/ios.htm?key=port
Search entire site for: 'FreeRTOS port to PIC18LF45K22 anyone?'.

Truncated match.
PICList Thread
'FreeRTOS port to PIC18LF45K22 anyone?'
2011\07\12@173846 by Robert Berger

flavicon
face
Sorry for cross posting here and also on the FreeRTOS forum, but maybe
here I'll get more responses.

I'm playing with the idea of porting FreeRTOS 7.0.1 to a PIC18LF45K22
with MPLAB and friends as my time permits.

I know that this architecture is suboptimal for a RTOS, but was
wondering if someone has done something similar already or if someone
would be interested in a joint porting effort.

The code will be contributed to the community.
What I've found so far:

*) In the "standard FreeRTOS download": PIC18_MPLAB which targets a
PIC18F452

*) in the community contributions:
interactive.freertos.org/entries/304854-freertos-ported-to-pic18f4520
which targets the PIC18F4520

*) in the community contributions:
http://interactive.freertos.org/entries/271252-freertos which targets
the PIC18F4520 (did not yet investigate what's the difference between
the two)

My understanding is, that for the PIC18LF45K22 at least some more
tweaking for the memory banks is needed.

Please advise.

Regards,

Robert..."Getting an education was a lot like having a sexual disease.
It made you unsuitable to a lot of jobs and you had the urge to pass it
on."- A weirdo quoting PTerry

My public pgp key is available at:
pgp.mit.edu:11371/pks/lookup?op=get&search=0x90320BF1

2011\07\13@031023 by Michael Watterson

face picon face
On 12/07/2011 22:38, Robert Berger wrote:
> I'm playing with the idea of porting FreeRTOS 7.0.1 to a PIC18LF45K22
> with MPLAB and friends as my time permits.
>
> I know that this architecture is suboptimal for a RTOS, but was
> wondering if someone has done something similar already or if someone
> would be interested in a joint porting effort.
>

Very sub-optimal. I looked at this. The 16F/18F is not the the right family for such a project.

I think someone did "sort of" get it on an 18F. What you need is a simpler scheme using timer interrupt and all the tasks called in turn via semaphores and the main program loop. My approach works for 10F/12F/16F and 18F. It's not an actual OS, but a simple framework.

Introduction
http://www.techtir.ie/node/1003432

Article
http://www.techtir.ie/software/jal/multitasking

comments
http://www.techtir.ie/node/1003431


FreeRTOS is good project. But not the way to go for 18F.

There is a way to do "true" Multitasking on 18F family, Olin has discussed this and I've discussed it with Kyle, the author of current JAL compiler. There is even a "Task" construct in JAL, but it's not much use.

Basically the lack of decent configurable stack, abillity to have stack frames and manipulate SP and Stack is the problem

2011\07\13@033319 by Tamas Rudnai

face picon face
On Wed, Jul 13, 2011 at 8:09 AM, Michael Watterson <spam_OUTmikeTakeThisOuTspamradioway.org>wrote:

> There is a way to do "true" Multitasking on 18F family, Olin has
> discussed this and I've discussed it with Kyle, the author of current
> JAL compiler. There is even a "Task" construct in JAL, but it's not much
> use.
>

I guess by 'true' multitasking you mean a preemptiv scheduler?


> Basically the lack of decent configurable stack, abillity to have stack
> frames and manipulate SP and Stack is the problem.
>

Actually you can read and write the STKPTR but then the hardware stack is
very limited, so most people implement the scheduler to save the entire
stack for the current task and restore it for the new one - as opposed to
configure stack frames for each and every single tasks you have.

Tamas




>

More... (looser matching)
- Last day of these posts
- In 2011 , 2012 only
- Today
- New search...