Datasheet

299
7593L–AVR–09/12
AT90USB64/128
• 7 - CFGOK - Configure Pipe Memory OK
Set by hardware if the required memory configuration has been successfully performed.
Cleared by hardware when the pipe is disabled. The USB reset and the reset pipe have no effect
on the configuration of the pipe.
• 6 - OVERFI - Overflow
Set by hardware when a the current Pipe has received more data than the maximum length of
the current Pipe. An interrupt is triggered if the FLERRE bit is set.
Shall be cleared by software. Setting by software has no effect.
• 5 - UNDERFI - Underflow
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.
• 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 Reserved.
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.
Bit 76543210
CFGOK OVERFI UNDERFI - DTSEQ1:0 NBUSYBK UPSTAX
Read/writeRRWRW RRRR
Initial value00000000