
RELEASED
PM73122 AAL1GATOR-32
DATASHEET
PMC-1981419
ISSUE 7
32 LINK CES/DBCES AAL1 SAR PROCESSOR
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
385
DS3:
Use the DS3 clock directly and bypass the SBI bus.
CLK_SOURCE_TX must be set to “000”.
Clock Master or Slave Mode:
The CLK_MSTR bit determines which side controls the clock. If
CLK_MSTR is ‘1’ then the local link side controls the clock, or clock
master mode. If CLK_MSTR is ‘0’ then the local link is slave to the SBI,
or clock slave mode
There is a global CLK_MSTR bit in the SBI Bus Configuration Register
(SBI_BUS_CFG_REG), which if set will forces all links to be in clock
master mode, and if clear will let it be decided on a per link basis.
There is a CLK_MSTR bit in the Extract/Insert Tributary Control
Indirect Access Data Register for configuring clock mode for each
tributary which is used when the global CLK_MSTR bit is ‘0’. In this
case, setting the CLK_MSTR bit will configure that tributary to be a
clock master and clearing the bit will configure it to be clock slave.
When in clock slave mode, the CLK_MODE field in the Extract
Tributary Control Indirect Access Data Register determines what
type of clocking is used for a particular tributary.
When in clock slave mode the clocking method can be either
monitor SBI buffer depth (using EXT_CKCTL interface), use
ClockRate field of EXT_LINKRATE, or use Phase field of
EXT_LINKRATE value passed across SBI. Phase mode is
recommended.
SBI Error Checking and Reporting
The following errors can be detected on a per link basis: FIFO overrun,
FIFO underrun, and SBI parity error. These all can be
enabled/disabled in the Insert/Extract Control Register.
Parity detection is done only on the drop bus, which is done by the
EXSBI block. Parity can be configured to be odd or even, and it is
default to be odd parity. Parity is checked at all times, including
overhead and unused tributaries. It is recommended that one of
the Physical Layer SBI devices (e.g. TEMUX) is enabled to drive
good parity at all times. (set the equivalent to the BUSMASTER
bit).