Functional Description - Nortel Circuit Card Installation Manual

Page 392 of 906

Functional description

CPU bus interface
553-3001-211 Standard 3.00
NT6D80 MSDL card
Figure 83 on page 393
MSDL card is divided into four major functional blocks:
• CPU bus interface
• Micro Processing Unit (MPU)
• Memory
• Serial interface
Two processing units serve as the foundation for the MSDL operation: the
Central Processing Unit (CPU) and the MSDL Micro Processing Unit
(MPU). CS 1000 Release 4.5 software, MSDL firmware, and peripheral
software control MSDL parameters. Peripheral software downloaded to the
MSDL controls MSDL operations.
The MSDL card's firmware and software do the following:
• communicate with the CPU to report operation status
• receive downloaded peripheral software and configuration parameters
• coordinate data flow in conjunction with the CPU
• manage data link layer and network layer signaling that controls
operations connection and disconnection
• control operation initialization and addressing
• send control messages to the operations
The CPU bus transmits packetized information between the CPU and the
MSDL MPU. This interface has a 16-bit data bus, an 18-bit address bus, and
interrupt and read/write control lines.
Shared Random Access Memory (RAM) between the CPU and the MSDL
MPU provides an exchange medium. Both the CPU and the MSDL MPU can
access this memory.
August 2005
illustrates the MSDL functional block diagram. The