Physical Layer Interface; Microprocessor System Bus Interface; Token Bus Lan Node - Motorola MC68824 User Manual

Figure 1-3 illustrates a typical system configuration using the TBC. The TBC, memory, and CPU
II
all communicate through a local bus. On the serial side, the TBC communicates through the IEEE
802.4G recommended standard serial interface to any modem also implementing this interface.
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BUS
STANDARD
PHYSICAL
INTERFACE
Figure 1-3. Token Bus LAN Node
1.5 PHYSICAL LAYER INTERFACE
COAX
CABLE
The TBC is a half-duplex controller which can be interfaced to any physical layer that implements
the IEEE 802.4 recommended standard serial interface at 1, 5, or 10 Mbps. The serial interface
supports two modes of operation: station management mode and MAC mode. In station man-
agement mode, commands may be given to an intelligent modem through the TBC. The serial
interface consists of a request channel and an indication channel. The request channel is from
the TBC to the modem and consists of TXCLK (supplied by the modem), TXSYMO, TXSYM1,
TXSYM2, and SMREQ. The indication channel is from the modem to the TBC and consists of
RXCLK (supplied by the modem), RXSYMO, RXSYM1, RXSYM2, and SMIND.
Both the TBC and the modem can request station management mode. The TBC requests station
management mode in order to give commands and the modem requests station management
mode in order to report error conditions. The TBC can either encode commands on its TXSYM
lines or send serial data commands on one of the TXSYM lines.
1.6 MICROPROCESSOR SYSTEM BUS INTERFACE
The host microprocessor can be any 8-, 16-, or 32-bit microprocessor. The microprocessor interface
on the TBC is that of the M68000 Family. The TBC provides byte swapping capability to enable
the user to operate with either Motorola or Intel byte ordering convention.
The TBC has a 32-bit non-multiplexed address bus and a separate 16-bit data bus, which may be
configured for 8-bit operation.
MC68824 USER'S MANUAL
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