L-USS820D-DB LSI, L-USS820D-DB Datasheet - Page 32

• Manufacturer Part Number: L-USS820D-DB
• Manufacturer: LSI

Specifications of L-USS820D-DB

• Operating Temperature (min): -20C
• Operating Temperature Classification: Commercial
• Operating Temperature (max): 85C
• Rad Hardened: No
• Lead Free Status / RoHS Status: Compliant

USS-820D
USB Device Controller
USB Device Controller
Register Interface
Table 29. Receive FIFO Flag Register (RXFLG)—Address: 09H; Default: 0000 1000B
These flags indicate the status of the data packets in the receive FIFO specified by EPINDEX. This register is
endpoint indexed.
32
Bit
7:6
RXFIF1
Bit 7
RXFIF[1:0]
R
Symbol
RXFIF0
Bit 6
Receive FIFO Index Flags (Read Only). These read-only flags indicate which data
packets are present in the receive FIFO (see below).
The RXFIF bits are updated after each write to RXCNT to reflect the addition of a data
packet. Likewise, the RXFIF bits are cleared in sequence after each setting of the
RXFFRC bit. The next-state table for RXFIF bits is shown below for operation in dual-
packet mode.
When the receive FIFO is programmed to operate in single-packet mode (RXSPM set in
EPCON), valid RXFIF states are 00 and 01 only.
In isochronous mode, RXOVF, RXURF, and RXFIF are handled using the following rule:
firmware events cause status change immediately, while USB events cause status
change only at SOF. RXFIF is incremented by the USB and decremented by firmware.
Therefore, setting RXFFRC decrements RFIF immediately. However, a successful USB
transaction within a frame increments RXFIF only at SOF.
If MCSR.FEAT = 1:
(continued)
RXFIF[1:0]
RXFIF[1:0]
during the intended frame (see RXFLG.RXFLUSH description). This flush occurs at
SOF, sets RXFLG.RXFLUSH, and causes RXFIF to decrement without firmware inter-
vention.
An old data set is flushed from an isochronous FIFO if it is not read out by firmware
00
01
10
00
01
10
00
01
10
00
11
11
11
Bit 5
—
—
Advance Write Marker
Advance Write Marker
Advance Write Marker
Advance Write Marker
Reverse Write Pointer
Not Possible—Device
will NACK any OUT.
ds1
Yes
Yes
RXFLUSH
No
No
Set RXFFRC
Set RXFFRC
Set RXFFRC
Set RXFFRC
Bit 4
Operation
R
Data Sets Present
Function/Description
RXEMP
ds0
Yes
Yes
No
No
Bit 3
Next RXFIF[1:0]
R
Unchanged
10/01
RXFULL
01
00
00
00
11
11
11
Status
Empty
2 sets
Bit 2
1 set
1 set
RXURF
Bit 1
Data Sheet, Rev. 7
September 2004
Agere Systems Inc.
R/W
RXOVF
Bit 0