AT90USB1286-16MU ATMEL [ATMEL Corporation], AT90USB1286-16MU Datasheet - Page 308

• Manufacturer Part Number: AT90USB1286-16MU
• Description: Microcontroller with 64/128K Bytes of ISP Flash and USB Controller
• Manufacturer: ATMEL [ATMEL Corporation]

308
AT90USB64/128
Set by hardware when a transaction underflow occurs in the current isochronous or interrupt
Pipe. The Pipe can’t send the data flow required by the device. A ZLP will be sent instead. An
interrupt is triggered if the FLERRE bit is set.
Shall be cleared by software. Setting by software has no effect.
Note: the Host controller has to send a OUT packet, but the bank is empty. A ZLP will be sent
and the UNDERFI bit is set
underflow for interrupt Pipe:
• 4 - Reserved
The value read from these bits is always 0. Do not set these bits.
• 3-2 - DTSEQ1:0 - Toggle Sequencing Flag
Set by hardware to indicate the PID data of the current bank:
00b Data0
01b Data1
1xb
For OUT Pipe, this value indicates the next data toggle that will be sent. This is not relative to the
current bank.
For IN Pipe, this value indicates the last data toggle received on the current bank.
• 1-0 - NBUSYBK1:0 - Busy Bank Flag
Set by hardware to indicate the number of busy bank.
For OUT Pipe, it indicates the number of busy bank(s), filled by the user, ready for OUT transfer.
For IN Pipe, it indicates the number of busy bank(s) filled by IN transaction from the Device.
00b All banks are free
01b 1 busy bank
10b 2 busy banks
11b Reserved.
• 7-0 - INRQ7:0 - IN Request Number Before Freeze
Enter the number of IN transactions before the USB controller freezes the pipe. The USB con-
troller will perform (INRQ+1) IN requests before to freeze the Pipe. This counter is automatically
decreased by 1 each time a IN request has been successfully performed.
Reserved.
Bit
Read/Write
Initial Value
Bit
Read/Write
Initial Value
INRQ7
RW
7
0
7
0
-
INRQ6
RW
RW
COUNTER1:0
6
0
6
0
INRQ5
RW
RW
5
0
5
0
CRC16
INRQ4
RW
RW
4
0
4
0
TIMEOUT
INRQ3
RW
RW
3
0
3
0
INRQ2
PID
RW
RW
2
0
2
0
DATAPID DATATGL
INRQ1
RW
RW
1
0
1
0
INRQ0
RW
RW
0
0
0
0
7593A–AVR–02/06
UPINRQX
UPERRX