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linhnc308
Joined: 16 Feb 2006 Posts: 9 Location: Viet Nam
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Problem with USB_CDC for PIC18F2450 |
Posted: Wed Sep 24, 2008 10:00 pm |
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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 |
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FvM
Joined: 27 Aug 2008 Posts: 2337 Location: Germany
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Posted: Wed Sep 24, 2008 11:28 pm |
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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. |
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linhnc308
Joined: 16 Feb 2006 Posts: 9 Location: Viet Nam
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Posted: Thu Sep 25, 2008 8:16 pm |
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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
Code: | //---pic18fxx5x memory locations
#if defined(__USB_4550__)
#byte UFRML = 0xF66
#byte UFRMH = 0xF67
#byte UIR = 0xF68
#byte UIE = 0xF69
#byte UEIR = 0xF6A
#byte UEIE = 0xF6B
#byte USTAT = 0xF6C
#byte UCON = 0xF6D
#byte UADDR = 0xF6E
#byte UCFG = 0xF6F
#define UEP0_LOC 0xF70
#else
#byte UFRML = 0xF60
#byte UFRMH = 0xF61
#byte UIR = 0xF62
#byte UIE = 0xF5C
#byte UEIR = 0xF63
#byte UEIE = 0xF5D
#byte USTAT = 0xF64
#byte UCON = 0xF65
#byte UADDR = 0xF5E
#byte UCFG = 0xF5F
#define UEP0_LOC 0xF4C
#endif |
Change the first line from
Code: | #if defined(__USB_4550__) |
to
Code: | #if defined(__USB_4550__) || defined(__USB_4450__) |
Because of memory allocation of USB block in 2550 and 2450 is the same, so we should keep it unchange when compile code.
That all, |
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