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Intel® PXA255 Processor Developer’s Manual 12-39
USB Device Controller
12.6.11 UDC Status/Interrupt Register 0 (USIR0)
USIR0, shown in Table 12-22, and USIR1, shown in Table 12-23, contain bits that are used to
generate the UDC’s interrupt request. Each bit in the UDC status/interrupt registers is logically
ORed together to produce one interrupt request. When the ISR for the UDC is executed, it must
read the UDC status/interrupt register to determine why the interrupt occurred. USIRx is level
sensitive. Be sure to clear USIRx as the last step before exiting the ISR.
The bits in USIR0 and USIR1 are controlled by a mask bit in the UDC Interrupt Control Register
(UICR0/1). The mask bits, when set, prevent a status bit in the USIRx from being set. If the mask
bit for a particular status bit is cleared and an interruptible condition occurs, the status bit is set. To
clear status bits, the core must write a 1 to the position to be cleared. The interrupt request for the
UDC remains active as long as the value of the USIRx is non-zero.
12.6.11.1 Endpoint 0 Interrupt Request (IR0)
The endpoint 0 interrupt request is set if the IM0 bit in the UDC control register is cleared and, in
the UDC endpoint 0 control/status register, the OUT packet ready bit is set, the IN packet ready bit
is cleared, or the sent STALL bit is set. The IR0 bit is cleared by writing a 1 to it.
12.6.11.2 Endpoint 1 Interrupt Request (IR1)
The interrupt request bit is set if the IM1 bit in the UDC interrupt control register is cleared and the
IN packet complete (TPC) in UDC endpoint 1 control/status register is set. The IR1 bit is cleared
by writing a 1 to it.
Table 12-22. USIR0 Bit Definitions
0x 4060_0058 USIR0 USB Device Controller
Bit
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
reserved
IR7
IR6
IR5
IR4
IR3
IR2
IR1
IR1
Reset x x x x x x x x x x x x x x x x x x x x x x x x 0 0 0 0 0 0 0 0
Bits Name Description
31:8 — reserved
7IR7
Interrupt Request Endpoint 7 (read/write 1 to clear)
1 = Endpoint 7 needs service.
6IR6
Interrupt Request Endpoint 6 (read/write 1 to clear)
1 = Endpoint 6 needs service.
5IR5
Interrupt Request Endpoint 5 (read/write 1 to clear)
1 = Endpoint 5 needs service.
4IR4
Interrupt Request Endpoint 4 (read/write 1 to clear)
1 = Endpoint 4 needs service.
3IR3
Interrupt Request Endpoint 3 (read/write 1 to clear)
1 = Endpoint 3 needs service.
2IR2
Interrupt Request Endpoint 2 (read/write 1 to clear)
1 = Endpoint 2 needs service.
1IR1
Interrupt Request Endpoint 1 (read/write 1 to clear)
1 = Endpoint 1 needs service.
0IR0
Interrupt Request Endpoint 0 (read/write 1 to clear)
1 = Endpoint 0 needs service.