VSC6134
Datasheet
2.16
Microprocessor Interface Description
This section describes the microprocessor interface unit (MPIU) of the VSC6134. This unit has four
primary functions:
●
Write register— Receives data and addresses from an external microprocessor and writes the data
into the register indicated by the address.
●
Read register—Receives an address from the microprocessor, reads the contents of the address and
transmits them back to the microprocessor.
●
●
Delivers acknowledgement of writes/reads to the microprocessor.
Delivers interrupts to the microprocessor.
When reading the 32-bit counter cache registers, the microprocessor must read the 16-bit MSB of the
count first (bits 31:16), at which time the 16-bit LSB of the count (bits 15:0) is transferred to a shadow
register. When the microprocessor reads the 16-bit LSB of the count, it is the shadow register that is
read.
2.16.1
External Microprocessor Modes and Timing
The microprocessor interface unit (MPIU) of the VSC6134 is capable of interfacing with both Motorola
and Intel microprocessors. The MPIU uses the MPSEL pin to determine the type of microprocessor
interface being used (Motorola or Intel). Synchronous or asynchronous operation is determined by the
MPMODE pin. A third pin, SYNSEL_DSN_WRN, determines the synchronous or pseudo-synchronous
mode to Motorola processors.
The following table lists the external signals that connect to the MPIU.
Table 65. External Microprocessor Interface Signals
Signal
Function
MPU_CLK
ASN_ALE
Microprocessor clock
1. Address strobe
2. Address latch enable
CSN
Chip select
SYNSEL_DSN_WRN
1. Select synchronous mode (0 = pseudo-synchronous, 1 = synchronous)
2. Data strobe
3. Write strobe
RWN_WRN_RDN
1. Read/Write
2. Write/Read
3. Read strobe
MPMODE
MPSEL
0 - Asynchronous (Intel only)
1 - Synchronous
0 - Motorola
1 - Intel
DTKN_RDY
INTN
1. Data acknowledge
2. Ready
Interrupt
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VMDS-10185 Revision 4.0
July 2006
VITESSE [ VITESSE SEMICONDUCTOR CORPORATION ]
