
Universal Serial Bus
M30240 Group
Rev.1.00 Sep 24, 2003 Page 306 of 360
Figure 3.20: USB Endpoint x IN CSR
3.2.2.15 USB Endpoint x IN MaxP Register
This register indicates the Maximum Packet size (MaxP) of the endpoint x (x = 1-4) IN packet. This
register should be set when the SET_DESCRIPTOR command is received from the host CPU. When
the MaxP > half of FIFO size, single buffer mode is set. When the MaxP <= half of FIFO size, double
buffer mode is set.
Figure 3.21 shows the structure of the USB Endpoint x IN Maximum Packet.
Figure 3.21: USB Endpoint x IN MaxP Register
3.2.2.16 USB Endpoint x OUT Control & Status Register
The USB Endpoint x OUT Control and Status Register contains the control and status information for
the specific OUT Endpoint (1-4).
OUT_PKT_RDY Flag
This bit is set to “1” after a data packet has been successfully received from the host. This should be
cleared to “0” after data has been read from the OUT FIFO. When the AUTO_CLR bit is “1”, the
OUT_PKT_RDY Flag is automatically cleared when a data packet, equal to the MaxP is unloaded.
When using double buffer mode, two or more packets of data are written to the OUT FIFO. After one
packet has been read, OUT_PKT_RDY will not become “0” even if “0” is written to the OUT_PKT_RDY
bit.
Bit Symbol
Bit Name
Function
R W
INxCSR0
IN_PKT_RDY Flag
0: Not ready
1: Ready
O O
Symbol
EPxICS (x=1-4)
Address
0319
16, 032116,
0329
16, 033116
When reset
00
16
USB Endpoint x IN Control and Status Register
b7
b5
b6
b4
b3
b2
b1
b0
INxCSR1
UNDER_RUN Flag
0: No FIFO underrun
1: FIFO underrun occured
O O
INxCSR2
SEND_STALL Bit
0: No action
1: Stall IN Endpoint x by CPU
O O
Note 1
Note 2
Note 1: Write "1" only or Read
Note 2: Write "0" only or Read
Note 3: Read only
Note 4: Write only - Read "0"
Note 5: Refer to Section 1.5.5 "Programming Notes" for this register.
INxCSR3
ISO Bit
0: Select non-isochronous transfer
1: Select isochronous transfer
O O
INxCSR4
INTPT Bit
0: Select non-rate feedback interrupt transfer
1: Select rate feedback interrupt transfer
O O
INxCSR5
TX_NOT_EPT Flag (Note 4)
0: Transmit FIFO is empty
1: Transmit FIFO is not empty
O X
Note 3
INxCSR6
FLUSH Bit
0: No action
1: Flush FIFO
INxCSR7
AUTO_SET Bit
0: AUTO_SET disabled
1: AUTO_SET enabled
O O
Note 4
Bit Symbol
Bit Name
Function
R W
IMAXP0 to
IMAXP7
Maximum packet size
(MAXP) of Endpoint x IN
packet
O O
Symbol
EPxIMP (x=1-4)
Address
031B
16, 032316, 032B16, 033316
When reset
00
16
USB Endpoint x IN MaxP Register
b7
b5
b6
b4
b3
b2
b1
b0
For endpoints that support
smaller FIFO size, unused bits
are not implemented. (Always
write "0" to those bits.)