PIC18 using MCC18 footprint sizes?

jcwren wrote on Wednesday, October 21, 2009:

Does anyone have any numbers for what the footprint of FreeRTOS is on a PIC18 part?  I realize, of course, that this will be dependent on what options are enabled, but I’m hoping in addition to the footprint, you might mention with what options.

I need to roughly size a project where FreeRTOS has been suggested.  At the moment, I don’t have MCC18 available where I can generate a simple project and find out for myself.  So any numbers someone can throw at me would be helpful. 

The numbers for any of the demo programs in the PIC18 examples would work well, too.


rtel wrote on Wednesday, October 21, 2009:

Not an answer to your question….but just to point out that the PIC18 is not an ideal target for any pre-emptive kernel.  One of the main problems is its segmented memory space, and what to do when a task stack staggers a segment.  The PIC24/33 and PIC32 are good targets however.


jcwren wrote on Thursday, October 22, 2009:

Oh, I’m fully aware of that.  You know I like I FreeRTOS, and if you’ve been unlucky enough to be exposed to my rants on PICs (18’s and below, haven’t used the newer ones), you’d know I’d rather be programming a 4004 system with DIP switches. 

But when you have people writing specs who have no grasp of how inefficient a PIC is, no idea about the compiler quirks, and no idea what *really* goes into an RTOS, you have a disaster waiting to happen. 

I’m pretty sure that with most of the options we need enabled we’re looking around a minimum of 30K of code space (shooting from the hip here), and enough RAM for very few tasks.

Looks like I’ll have to compile up a version and see.  If I do, I’ll post my results back to the list.