PIC 18F4550 - EUSART does not generate interrupts

Hi All,

I have the following problem with the PIC18F4550.
The EUSART is initialized as follows:
       movlw b'11111111'
       movwf TRISC,ACCESS
       movlw low(d'1249')
       movwf SPBRG,ACCESS
       movlw high(d'1249')
       movwf SPBRGH,ACCESS
       movlw b'00000100'
       movwf TXSTA,ACCESS
       movlw b'10000000'
       movwf RCSTA,ACCESS
       movlw b'00001000'
       movwf BAUDCON,ACCESS
       bsf PIE1,RCIE,ACCESS
       bsf IPR1,RCIP,ACCESS
       bsf RCSTA,CREN,ACCESS

Then the interrupts are enabled:
       bcf RCON,IPEN,ACCESS
       bsf INTCON,PEIE, ACCESS
       bsf INTCON,GIE, ACCESS

(I have also tried the version with interrupt priority switched on,
that's why I have "bsf IPR1,RCIP,ACCESS", howeve this is simply
ignored when " bcf RCON,IPEN,ACCESS" is used).

The result is however, that PIC doesn't call the interrupt routine.
I have a special variable to detect if the routine was ever called:

Code at 0x08:
       call            HiIrq,FAST

HiIrq:
       pop ; According to the errata 80220g.pdf
       banksel int_flag
       setf int_flag, BANKED
       call ser_rx_irq
       retfie FAST

The int_flag variable is still equal to 0 (set in the initial code).
However I can see, that the INTCON is set to 0xc5, and that EUSART
receive something on the serial line (RCSTA contains initially 0x90,
than 0x94 - <frame error>, later 0x96 - <frame error & data lost>)
The RCIF is also set (PIR1 contains 0x20), and RCIE as well (PIE1
contains
0x20).

How is it possible, that with INTCON<7> set to 1, INTCON<6> set to 1,
and
both RCIE and RCIF set to '1' the interrupt routine is not called?

The PIC does not hang, as the USB code, which I use for debugging
works
perfectly.

--
TIA & regards,
Wojtek Zabolotny
wzab@ise.pw.edu.pl

The situation is even worse. This PIC does not respond to any
interrupts.
I have added:
bsf INTCON,INT0IE, ACCESS
to the initialization routine
and then:

HiIrq:
			pop ; According to the errata 80220g.pdf
			banksel int_flag
			setf int_flag, BANKED
			call ser_rx_irq
			call int0_irq
			retfie FAST

int0_irq:
			btfss INTCON,INT0IF,ACCESS
			return
			bcf   INTCON,INT0IE,ACCESS
			return


What I can see is that INTCON has initially value 0xd5, and then,
after I press the button connected to the INT0 line - 0xd7.
The HiIrq routine is never called, even though GIE and PEIE bits are
set.
Does it mean, that this chip is damaged? What else could cause such a
problem?
Unfortunately I'm currently on my hollidays and this is the only
18F4550 I have with me :-(/

I have found the following post about similar problems:
http://www.motherboardpoint.com/t93255-interrupt-not-firing-on-pic18f.html

I checked that in my code (based on the Bradley Minch's USB firmware)
I had
the _DEBUG_ON_4L option set. After I replaced it with _DEBUG_OFF_4L,
the interrupts
started to work!

I'm quite surprised, that setting of this option breaks interrupts...
In the datasheet (39632D.pdf) there is nothing about it...
--
Regards, Wojtek