Freescale Semiconductor, Inc.
Advance Information — 68HC(9)12D60
Section 16. Motorola Interconnect Bus
16.1 Contents
16.2 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .263
16.3 Push-pull sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .264
16.4 Biphase coding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .265
16.5 Message validation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .266
16.6 Interfacing to MI Bus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .268
16.7 MI Bus clock rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .270
16.8 SCI0/MI Bus registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .270
16.2 Introduction
The Motorola Interconnect Bus (MI Bus) is a serial communications
protocol which supports distributed real-time control efficiently and with
a high degree of noise immunity, at a typical data transfer bit rate of
20kHz. The MI Bus is suitable for medium speed networks requiring very
low cost multiplex wiring; only one wire is required to connect to slave
(1)
devices.
The MI Bus uses a push-pull sequence to transfer data. The master
device, which in this case is the 68HC(9)12D60, sends a push field to the
slave devices connected to the bus. The push field contains data plus an
address that is recognized by one of the slaves. The slave addressed
returns data which the master pulls from the MI Bus over the same wire.
Specific details of the message format are covered later in this section.
1. Related information on Motorola’s MI Bus is contained in the following Motorola publications:
EB409/D — The MI Bus and Product family for Multiplexing Systems
AN475/D — Single Wire MI Bus Controlling Stepper Motors
BR477/D — Smart Mover – Stepper Motors with Integrated Serial Bus Controller
68HC(9)12D60 — Rev 4.0
MOTOROLA
Advance Information
Motorola Interconnect Bus
263
For More Information On This Product,
Go to: www.freescale.com
MOTOROLA [ MOTOROLA ]
