Specification
NET2272 USB Peripheral Controller
______________________________________________________________________________
NetChip Technology, Inc., 2003
Patent Pending
335 Pioneer Way, Mountain View, California 94041
TEL (650) 526-1490
FAX (650) 526-1494
http://www.netchip.com
Rev 1.2, October 15, 2003
69
8.6.3 (Address 07h; EP_STAT1) -- Endpoint Status Register (high byte)
Bits
Description
Read
Write
Default
Value
7
Buffer Flush. Writing a 1 to this bit causes the packet buffer to be flushed and the
corresponding EP_AVAIL register to be cleared. This bit is self-clearing. This bit
should always be written after an endpoint configuration (direction, address, etc.) has
been changed. This bit should not be asserted during a split-mode DMA if Page
Select is selecting another endpoint.
0
Yes/Flush
0
6
Local OUT ZLP. When set, this bit indicates that the current local buffer contains a
zero length packet.
Yes
No
0
5
USB STALL Sent. The last USB packet could not be accepted or provided because
the endpoint was stalled, and was acknowledged with a STALL. Writing a 1 clears
this bit.
Yes
Yes/CLR
0
4
USB IN NAK Sent. The last USB IN packet could not be provided, and was
acknowledged with a NAK. Writing a 1 clears this bit.
Yes
Yes/CLR
0
3
USB IN ACK Rcvd. The last USB IN data packet transferred was successfully
acknowledged with an ACK from the host. Writing a 1 clears this bit.
Yes
Yes/CLR
0
2
USB OUT NAK Sent. The last USB OUT data packet could not be accepted, and
was acknowledged with a NAK to the host. Writing a 1 clears this bit.
Yes
Yes/CLR
0
1
USB OUT ACK Sent. The last USB OUT data packet transferred was successfully
acknowledged with an ACK to the host. Writing a 1 clears this bit.
Yes
Yes/CLR
0
0
Timeout. For an IN endpoint, the last USB packet transmitted was not acknowledged
by the Host PC, indicating a bus error. The Host PC will expect the same packet to be
retransmitted in response to the next IN token. For an OUT endpoint, the last USB
packet received had a CRC or bit-stuffing error, and was not acknowledged by the
NET2272. The Host PC will retransmit the packet. Writing a 1 clears this bit.
Yes
Yes/CLR
0
8.6.4 (Address 08h; EP_TRANSFER0) Transfer Count Register (Byte 0)
Bits
Description
Read
Write
Default
Value
7:0
EP_TRANSFER[7:0]. For IN endpoints, this field determines the total number of
bytes to be sent to the host. This field should be written before any packet data is
written to the buffer. When the count reaches zero, any remaining data in the buffer
is validated. Note that validation takes about 100 nsec. Writing zero to
EP_TRANSFER0 when EP_TRANSFER1 and EP_TRANSFER2 have a value of
0 validates the contents of this IN endpoint buffer regardless of the state of the Auto
Validate bit; if the buffer is empty, writing zero to EP_TRANSFER0 validates a
Zero Length Packet.
For OUT endpoints, this counter is cleared when the NAK OUT packets bit is cleared
(EP_RSPCLR bit 7). This counter is incremented for every byte read from the
packet buffer. If 16-bit mode is selected and only one of the two bytes is valid, the
counter will only increment by 1.
Yes
Yes
0
8.6.5 (Address 09h; EP_TRANSFER1) Transfer Count Register (Byte 1)
Bits
Description
Read
Write
Default
Value
7:0
EP_TRANSFER[15:8].
Yes
Yes
0
8.6.6 (Address 0Ah; EP_TRANSFER2) Transfer Count Register (Byte 2)
Bits
Description
Read
Write
Default
Value
7:0
EP_TRANSFER[23:16].
Yes
Yes
0
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