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Intel® PXA255 Processor Developer’s Manual 12-43
USB Device Controller
12.6.13.1 UDC Frame Number MSB (FNMSB)
The UFNHR[FNMSB] is the three most significant bits of the 11-bit frame number contained in
the last received SOF packet. The remaining bits are located in the UFNLR. This information is
used for isochronous transfers. These bits are updated every SOF.
12.6.13.2 Isochronous Packet Error Endpoint 4 (IPE4)
The isochronous packet error for Endpoint 4 is set if Endpoint 4 is loaded with a data packet that is
corrupted. This status bit is used in the interrupt generation of endpoint 4. To maintain
synchronization, the software must monitor this bit when it services an SOF interrupt and reads the
frame number. This bit is not set if the token packet is corrupted or if the sync or PID fields of the
data packet are corrupted.
12.6.13.3 Isochronous Packet Error Endpoint 9 (IPE9)
The isochronous packet error for Endpoint 9 is set if Endpoint 9 is loaded with a data packet that is
corrupted. This status bit is used in the interrupt generation of endpoint 9. To maintain
synchronization, software must monitor this bit when it services the SOF interrupt and reads the
frame number. This bit is not set if the token packet is corrupted or if the sync or PID fields of the
data packet are corrupted.
Table 12-24. UFNHR Bit Definitions
0x 4060_0060 UFNHR 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
SIR
SIM
IPE14
IPE9
IPE4
3-Bit
Frame
Number
MSB
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 1 0 0 0 0 0 0
Bits Name Description
31:8 — reserved
7SIR
SOF Interrupt Request (read/write 1 to clear)
1 = SOF has been received.
6SIM
SOF interrupt mask
0 = SOF interrupt enabled.
1 = SOF interrupt disabled.
5IPE14
Isochronous Packet Error Endpoint 14 (read/write 1 to clear)
1 = Status indicator that data in the endpoint FIFO is corrupted
4 IPE9
Isochronous Packet Error Endpoint 9 (read/write 1 to clear)
1 = Status indicator that data in the endpoint FIFO is corrupted
3 IPE4
Isochronous Packet Error Endpoint 4 (read/write 1 to clear)
1 = Status indicator that data in the endpoint FIFO is corrupted
2:0 FNMSB
Frame Number MSB.
Most significant 3-bits of 11-bit frame number associated with last receive SOF.