Problem with USB_CDC for PIC18F2450

[linhnc308]

Hi all,

I'm having a problem with PIC18F2450. I tried to create USB-to-COM with PIC USB. I used example code from CCS compiler, file name: ex_usb_serial.c

When I tried with PIC18F2550, It OK, no problem. PC could recognize the board and virtual COM port created successful .

The problem is, when I changed to PIC18F2450 in the code ("#include <18F2550.h>" to "#include <18F2450.h>"), then I compile, there are no error, put HEX file to PIC18F2450 by PICKit2, OK. But the PC can not recognize my USB, nothing happen when I connect usb to PC .

I used the same board for both PIC18F2550 and PIC18F2450.
pls help me to solve this. Thank.
CCS version is 4.057

[FvM]

Hello,

I'm not aware of other differences between the chips than less memory and some missing peripherals. It seems to me, that the core and USB functions are identical.

However, not recognized means, that the internal pullup resistors triggering the device enumeration aren't activated. If so, some basic initialization of the USB interface is apparently missing. (The device may also have been recognized as a non-operational USB device, did you check that?).

Or it's an unnoticed circuit assembly failure.

[linhnc308]

I found the problem. It is because of pic18_usb.h file. I used CCS version 4.057 and it still had this problem. To fix this, find the code like below