CCS and USB chip and 73% rom BUG ?

[jmer]

Using CCS version 4

When code size reach around 73% 74% in a 18Fxxxx usb chip,
usb cease to work.

Even more if you use a smallest rom version of the chip usb won't work at all, because usb code reaches the 73% limit without any user code.

The same code put in a bigger rom will work tough!

[Ttelmah]

What compiler version?.
What USB implementation (CDC/HID etc.).
What actual chip family?. There are several different chip versions with USB now...
What 'else' are you doing (Bootloader? debugging? etc..).
I have the the USB serial code, in a 2450, which has just 16KB of ROM, and this only uses 39% of the ROM, including a parser for over 30 different commands, and the code to handle them. Compiling with 4.070. Have got another set of code based on the same 'core', running at 82% ROM used, and running fine.
I'd suggest you have something else, not considered as part of the 'code' (a bootloader for example), that is using perhaps 25% of your ROM, and hence leads to failure when you get to 75%.

Best Wishes

[Guest]

ccs v4.005
USB CDC

18F4550
18F4458
18F2450

It could be a RAM problem also.
What I mean is that resources are problably not well evaluated.
My program works. If a add one more instruction, a copy of a good instruction,the program builds sucessfully, but USB do not work any more, does not even enumerate en pluged.

As I remember we tried CDC on 2450 and it builds, but did not work, move the same code to a bigger chip and it worked.

This king of problem are very hard to detect, because you got a success message from the compiler, resource indicators are within limits but USB CDC communication does not work.

Now you know, be suspicious!
Cordially

I think the resource indicators give you an OK when it's not!