Pin Descriptions
MU9C8338 10/100Mb Ethernet Filter Interface
INCR (Increment Time Stamp Counters, Input, TTL)
/WRITE (Processor Port Read/Write, Input, TTL)
INCR is a user command to invoke the built-in purge
routine. Both STCURR and STPURG 8-bit counters are
advanced one count on the rising edge of INCR, and the
time stamp stored with each LANCAM entry is compared
with STPURG. Matching entries subsequently are purged
or deleted. This pin must be configured, if it is required, by
setting bit 2 and bit 3 in the System Target (STARG)
register. Each counter can be incremented individually
through the Processor Port. (see Operational
Characteristics: STARG System Target Register
Mapping).
Read/Write determines the direction of data flow into or
out of the MU9C8338 host processor interface. If /WRITE
is LOW, the data is written into the register selected by
A[7:0] and /PCS or /PCSS; if HIGH, the data is read from
the register selected by A[7:0] and /PCS or /PCSS.
A[7:0] (Processor Port Address, Input, TTL)
Processor Address bus A[7:0] selects the MU9C8338
register accessed by the host processor.
D[15:0] (Processor Port Data, Input/Output, Tri-state,
TTL)
Processor Data bus D[15:0] is the tri-state processor data
bus for the MU9C8338.
Host Processor Interface
The Host Processor interface is asynchronous to the
System Clock. This interface is controlled by the /PCS or
/PCSS (whichever is appropriate) and PROC_RDY
signals, which form the handshaking between the
processor and the MU9C8338. This allows the end system
to use a processor that runs at a different clock speed than
the clock required by the MU9C8338. (see Timing
Diagrams: Timing Data for Host Processor Interface).
PROC_RDY (Processor Port Ready, Output, Tri-state,
TTL)
When reading from or writing to any MU9C8338 internal
register, the PROC_RDY tri-state output goes LOW on the
falling edge of /PCS or /PCSS. If it is a read cycle,
PROC_RDY goes HIGH on the rising edge of SYSCLK
once data is available. If it is a write cycle, PROC_RDY
goes HIGH on the rising edge of SYSCLK when the
internal register is ready to accept data.
/PCS (Processor Port Chip Select, Input, TTL)
Processor Chip Select is taken LOW by the host processor
to gain access to the MU9C8338 Port or Chip registers.
/INTR (Processor Interrupt, Output, TTL)
/INTR goes LOW to signal that one of the four
configurable interrupt conditions have been satisfied. The
four separate conditions are configured by setting bits in
the appropriate register. /INTR returns HIGH when the
appropriate register is read. See Table 2 for details of
which interrupt conditions are possible and which register
must be read to reset the /INTR pin to HIGH.
/PCSS (Processor Port Chip Select System, Input, TTL)
Processor Chip Select System is taken LOW by the host
processor to gain access to the MU9C8338 System
registers or to access the LANCAM.
Table 2: /INTR Settings
Register Required to To clear /INTR, Read
Select Interrupt
Interrupt Condition
Condition
PTARG
RSTAT. Please note that /INTR will only return
The MII port has parsed an incoming packet. The DA lookup
HIGH when all possible result data has been read. has been performed and the result data is available to be
read from RDAT register.
STARG
SSTAT. Please note that /INTR will only return
HIGH when the LANCAM has become not full.
Therefore, after the SSTAT register read has
confirmed the status of the interrupt condition, an
entry should be removed from the LANCAM by
using the PURGE sequence.
The /FF output from the LANCAM(s) has indicated that the
LANCAM is full. When reading the SSTAT register, a full
condition is indicated by bit 0 = 0.
Rev. 1a
5
MUSIC [ MUSIC SEMICONDUCTORS ]
