NET2270 datasheet(22/90 Pages) ETC2

22 / 90 page

Specification

NET2270 USB Interface Controller

______________________________________________________________________________

 NetChip Technology, Inc., 2003

335 Pioneer Way, Mountain View, California 94041

TEL (650) 526-1490

FAX (650) 526-1494

http://www.netchip.com

Rev 3.6, April 17, 2003

4.5

I/O Transactions

I/O transactions are those in which a CPU on the local bus accesses registers or packet buffers within the NET2270.

4.5.1 Non-Multiplexed I/O Read

Non-multiplexed I/O reads are started when both CS# and IOR# are asserted. The address must be valid T4 before

CS# and IOR# are both asserted. Valid read data is driven onto the data bus within T6 after CS# and IOR# are both

asserted. The read transaction ends and the data bus floats when either CS# or IOR# are de-asserted. A new I/O

read transaction cannot be started until the T8A recovery time has expired, and a new I/O write transaction cannot

be started until the T8B recovery time has expired. ALE must be held low for non-multiplexed mode.

NetChip Technology; NET2270; Non-Multiplexed I/O Read; 12/10/02; IORD.TD

0ns

25ns

50ns

75ns

LA[4:0]

CS#

IOR#

LD[15:0]

4.5.2 Multiplexed I/O Read

Multiplexed I/O reads are started when the address is driven onto the lower bits of the data bus, and ALE is pulsed.

Once the address has been latched into the NET2270, the data phase is initiated with the assertion of both CS# and

IOR#. To prevent bus contention on the data bus, CS# and IOR# should not be asserted until the local bus master

has tri-stated the address. Valid read data is driven onto the data bus within T6 after CS# and IOR# are both

asserted. The read cycle ends and the data bus floats when either CS# or IOR# are de-asserted. A new I/O read

transaction cannot be started until the T8A recovery time has expired, and a new I/O write transaction cannot be

started until the T8B recovery time has expired.

NetChip Technology; NET2270; Multiplexed I/O Read; 12/10/02; IORD_MPX.TD

0ns

25ns

50ns

75ns

100ns

ALE

CS#

IOR#

LD[15:0]

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