Serial Interface with Time Slot Assigner
7-96
MC68360 USER’S MANUAL
MOTOROLA
5. PAPAR bits 6, 7, and 8 = 1. Configures L1TXDa, L1RXDa, and L1RCLKa.
6. PADIR bits 6 and 7 = 1. PADIR bit 8 = 0. Configures L1TXDa, L1RXDa, and
L1RCLKa.
7. PCPAR bits 3, 10, and 11 = 1. Configures L1RQa, L1TSYNCa, and L1RSYNCa.
8. PCDIR bit 3 = 0. L1RQa is an input. L1TSYNCa will perform the L1GRa function
and is therefore an output, but it does not need to be configured with a PCDIR bit.
L1RSYNCa is an input, but it does not need to be configured with a PCDIR bit.
9. SIGMR = $04. Enable TDMa (one static TDM).
10.1SICMR is not used.
11.1SISTR and SIRP do not need to be read, but can be used for debugging
information once the channels are enabled.
12.1Enable the SCC1 for HDLC operation (to handle the LAPD protocol of
the D channel), and set SCC2 and SCC4 as desired.
7.8.7 SI GCI Support
The normal mode of the GCI, also known as the ISDN-oriented modular rev 2.2 (IOM-2),
and the SCIT are fully supported by the QUICC. The QUICC also supports the D channel
access control in S/T interface terminals by using the command/indication (C/I) channel for
that function.
The GCI bus consists of four lines: two data lines, a clock, and a frame synchronization line.
Usually, an 8-kHz frame structure defines the various channels within the 256-kbps data
rate. The QUICC can support two independent GCI buses and has independent receive and
transmit sections for each one. The interface can also be used in a multiplexed frame struc-
ture on which up to eight physical layer devices multiplex their GCI channels. In this mode,
the data rate would be 2048 kbps.
In the GCI bus, the clock rate is twice the data rate. The SI divides the input clock by two to
produce the data clock.
The QUICC also has data strobe lines, and the 1
×
data rate clock L1CLKOx output pins.
These signals are used for interfacing devices to GCI that do not support the GCI bus.
The GCI signals for each transmit and receive channel are as follows:
L1RSYNCx—Used as GCI sync signal; input to the QUICC. This signal indicates that
the clock periods following the pulse designate the GCI frame.
L1RCLKx—Used as GCI clock; input to the QUICC. The L1RCLKx signal is twice the
data clock.
L1RXDx—Used as GCI receive data; input to the QUICC.
L1TXDx—Used as GCI transmit data; open-drain output. Valid only for the bits that are
supported by the IDL; three-stated otherwise.
L1CLKOx—Optional signal; output from QUICC. This 1
×
clock output can be used to
clock devices that do not interface directly to GCI. If the double-speed clock