Motorola MSC8101 ADS User's Guide Page 212

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10-10 MSC8101 User’s Guide
Multi-Channel Controllers (MCCs)
Line Clock (TLCLK) sourcing L1TCLK and the Ingress Clock (ICLK) connected to
L1RCLK (see Figure 10-5).
The PM6388 T1/E1 PHY transceiver is initialized in software through the Init_PHY()
function. The driver code sets up the PHY to be in internal loopback mode to enable
external PHY loopback.
10.3 Configure the Channels
Channel configuration proceeds in two steps:
Configure the global MCC resources applicable to all the channels supported by the
MCC.
Configure the individual, channel-specific parameters for the assigned protocol.
The main data structures for programming the MCC are held in the CPM DPRAM.
However, several other structures must reside in memory external to the CPM, either in
the on-device SRAM or in a memory device connected to the PowerPC system bus. The
next sections describe the global and channel-specific data structures for configuring
MCC resources.
10.3.1 Set Up the Global MCC Parameters
Each MCC has a set of global parameters that are held in DPRAM and are common to all
channels within that MCC. The global parameters define a base for the Transmit (Tx) and
Receive (Rx) circular buffer descriptor (BD) tables, the maximum buffer size, the number
of receive frame interrupts that cause an interrupt to the SC140 core, and the interrupt
queue addresses. The buffer descriptor tables, which are stored in on-chip SRAM, define
the Tx and Rx data buffer locations and maintain status information on received and
transmitted data frames. The global parameters provide the common functionality for all
active channels on each MCC.
The following parameters must be set up before the channel-specific parameters are
assigned:
MCCBASE. Defines the starting address of the 512 KB BD segment. In this case, it
is set to 0x1000000 via the variable BDRING_BASE in the header file.
MCCSTATE. Set to all zeros to define the initial MCC state.
MRBLR. Defines the maximum number of bytes written to a receive buffer before a
move to the next buffer. For transparent mode, the MRBLR should be assigned the
same length as the buffers, 64 bytes in this example.
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