mpc823rg Freescale Semiconductor, Inc, mpc823rg Datasheet - Page 599

• Manufacturer Part Number: mpc823rg
• Description: Mpc823 Powerquicc Integrated Communications Processor For Portable Systems
• Manufacturer: Freescale Semiconductor, Inc

16.7.7 GCI Interface Operation
The normal mode of the general circuit interface (GCI) and SCIT are fully supported by the
MPC823. It 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 8kHz frame structure defines the various channels within the 256kbps data rate.
The MPC823 supports an independent GCI bus and has independent receive and transmit
sections. The interface can also be used in a multiplexed frame structure on which up to
eight physical layer devices can multiplex their GCI channels. In this mode, the data rate
would be 2,048kbps. In the GCI bus, the clock rate is twice the data rate. The serial interface
divides the input clock by two to produce the data clock. The MPC823 also has data strobe
lines that are used as an interface for devices that do not support the GCI bus. The GCI
signals for each transmit and receive channel are as follows:
L1xCLK
L1xSYNC
L1RXDx
L1TXDx
11. SISTR and SIRP do not need to be read, but can be used for debugging information
12. Enable SCC2 to HDLC operation (to handle the LAPD protocol of the D channel). Set
• L1RSYNC A —Used as a GCI sync signal. Input to the MPC823. This signal indicates
• L1RCLK A —Used as a GCI clock. Input to the MPC823. The L1RCLK A signal is twice
• L1RXD A —Used as a GCI receive data. Input to the MPC823.
• L1TXD A —Used as a GCI transmit data. Open-drain output. Valid only for the bits that
that the clock periods following the pulse designate the GCI frame.
the data clock.
are supported by the IDL. Otherwise, it is three-stated.
once the channels are enabled.
SCC2 and SMC1 to transparent operation.
(2X THE DATA RATE)
B1
B1
Freescale Semiconductor, Inc.
For More Information On This Product,
Figure 16-59. GCI Bus Signals
MPC823 REFERENCE MANUAL
Go to: www.freescale.com
B2
B2
MONITOR
MONITOR
Communication Processor Module
D1 D2
D1 D2
(CLOCK IS NOT TO SCA
C/ I
C/ I
T E
T E
16-147