PIC18F2450/4450
Each error bit is set as soon as the error condition is
detected. Thus, the interrupt will typically not
correspond with the end of a token being processed.
14.5.3
USB ERROR INTERRUPT STATUS
REGISTER (UEIR)
The USB Error Interrupt Status register (Register 14-9)
contains the flag bits for each of the error sources
within the USB peripheral. Each of these sources is
controlled by a corresponding interrupt enable bit in
the UEIE register. All of the USB error flags are ORed
together to generate the USB Error Interrupt Flag
(UERRIF) at the top level of the interrupt logic.
Once an interrupt bit has been set by the SIE, it must
be cleared by software by writing a ‘0’.
REGISTER 14-9: UEIR: USB ERROR INTERRUPT STATUS REGISTER
R/C-0
U-0
—
U-0
—
R/C-0
R/C-0
R/C-0
R/C-0
R/C-0
BTSEF
BTOEF
DFN8EF
CRC16EF
CRC5EF
PIDEF
bit 7
bit 0
Legend:
R = Readable bit
-n = Value at POR
C = Clearable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared x = Bit is unknown
bit 7
BTSEF: Bit Stuff Error Flag bit
1= A bit stuff error has been detected
0= No bit stuff error
bit 6-5
bit 4
Unimplemented: Read as ‘0’
BTOEF: Bus Turnaround Time-out Error Flag bit
1= Bus turnaround time-out has occurred (more than 16 bit times of Idle from previous EOP elapsed)
0= No bus turnaround time-out
bit 3
bit 2
bit 1
bit 0
DFN8EF: Data Field Size Error Flag bit
1= The data field was not an integral number of bytes
0= The data field was an integral number of bytes
CRC16EF: CRC16 Failure Flag bit
1= The CRC16 failed
0= The CRC16 passed
CRC5EF: CRC5 Host Error Flag bit
1= The token packet was rejected due to a CRC5 error
0= The token packet was accepted
PIDEF: PID Check Failure Flag bit
1= PID check failed
0= PID check passed
DS39760A-page 146
Advance Information
© 2006 Microchip Technology Inc.
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