PM4351-1 Datasheet, PDF (373/485 Pages) PMC-Sierra, Inc – COMBINED E1/T1 TRANSCEIVER/FRAMER

STANDARD PRODUCT
DATA SHEET
PMC-1970624
ISSUE 10
PM4351 COMET
COMBINED E1/T1 TRANSCEIVER
12 TEST FEATURES DESCRIPTION
Simultaneously asserting the CSB, RDB and WRB inputs causes all output pins
and the data bus to be held in a high-impedance state. This test feature may be
used for board testing.
Test mode registers are used to apply test vectors during production testing of
the COMET. Test mode registers (as opposed to normal mode registers) are
mapped into addresses 100H-1FFH.
Test mode registers may also be used for board testing. When all of the
constituent Telecom System Blocks within the COMET are placed in test mode 0,
device inputs may be read and device outputs may be forced via the
microprocessor interface (refer to the section "Test Mode 0" for details).
Notes on Test Mode Register Bits:
1. Writing values into unused register bits has no effect. Reading unused bits
can produce either a logic 1 or a logic 0; hence unused register bits should be
masked off by software when read.
2. Writeable test mode register bits are not initialized upon reset unless
otherwise noted.
PROPRIETARY AND CONFIDENTIAL
349