MC68LC302 Datasheet, PDF (69/169 Pages) Motorola, Inc – Low Power Integrated Multiprotocol Processor Reference Manual

Communications Processor (CP)
4.2 SERIAL CHANNELS PHYSICAL INTERFACE
The serial channels physical interface joins the physical layer serial lines to the two SCCs
and the two SMCs. (The separate three-wire SCP interface is described in Serial Commu-
nication Port (SCP) on page 25.)
The IMP supports five different external physical interfaces from the SCCs:
1. NMSI—Nonmultiplexed Serial Interface
2. PCM—Pulse Code Modulation Highway
3. IDL—Interchip Digital Link
4. GCI—General Circuit Interface
4.2.1 Serial Interface Registers
There are two serial interface registers: SIMODE and SIMASK. The SIMODE register is a
16-bit register used to define the serial interface operation modes. The SIMASK register is
a 16-bit register used to determine which bits are active in the B1 and B2 channels of ISDN.
4.2.1.1 SERIAL INTERFACE MODE REGISTER (SIMODE) . If the IDL or GCI mode is
used, this register allows the user to support any or all of the ISDN channels independently.
Any extra SCC channel can then be used for other purposes in NMSI mode. The SIMODE
register is a memory-mapped read-write register cleared by reset. The changes to this reg-
ister are marked in BOLD.
15
SETZ
14
SYNC/SCIT
13
SDIAG1
12
SDIAG0
11
SDC2
10
SDC1
9
B2RB
8
B2RA
7
B1RB
6
B1RA
5
DRB
4
DRA
3
MSC3
2
MSC2
1
MS1
0
MS0
SETZ—Set L1TXD to Zero (valid only for the GCI interface)
0 = Normal operation
1 = L1TXD output set to a logic zero (used in GCI activation
SYNC/SCIT—SYNC Mode/SCIT Select Support (valid only in PCM mode)
0 = One pulse wide prior to the 8-bit data
1 = N pulses wide and envelopes the N-bit data
The SCIT (Special Circuit Interface T) interface mode is valid only in GCI mode.
0 = SCIT support disabled
1 = SCIT D-channel collision enabled. Bit 4 of channel 2 C/I used by the IMP for receiv-
ing indication on the availability of the S interface D channel.
4-2
MC68LC302 REFERENCE MANUAL
MOTOROLA