Resources used by ICD3 debugger

hello188 · Joined: 02 Jun 2010 Posts: 74

Hi. I have been debugging my firmware using MPLAB ICD3. It had been working fine until the program memory usage became about 98%.

The program seems to work fine when downloaded and operated alone. However, the debugging interface doesn't seem to work and the target goes to reset state right after I press run button.

Is there resource requirement in Flash in order to use debugger?

thanks

ckielstra · Joined: 18 Mar 2004 Posts: 3680 Location: The Netherlands

Yes, when debugging there is a small client program installed in top of your Flash memory. How large this is depends on the type of programmer you use, the PIC model and the MPLAB version. For details see the help file for your debugger that got installed with MPLAB. I didn't install the ICD software so can't tell you where to look exactly but what I remember from a previous project you'll have to open the ICD help topic and then search for 'resources'.

A memory usage of 98% is big trouble and will cost you a lot of time (== money) to squeesh in new features and bug fixes.
As a general rule of thumb: when designing a new device, always release your first prototype with 50% free memory space. Future customer changes are going to fill the remainder.

Ttelmah · Joined: 11 Mar 2010 Posts: 19539

The 'help' in MPLAB for the debugger will tell you the resources needed. It varies with different chips. Typically a little RAM (few bytes), a couple of stack levels, and a few hundred bytes of ROM.
On most chips anything over perhaps 90% won't work.
Agreed with Ckielstra, a prototype reaching 98% usage, is a sure message that you need to switch to a bigger chip.