M68HC12A4EVB Freescale Semiconductor, M68HC12A4EVB Datasheet - Page 243

• Manufacturer Part Number: M68HC12A4EVB
• Manufacturer: Freescale Semiconductor

Specifications of M68HC12A4EVB

• Lead Free Status / Rohs Status: Not Compliant

Chapter 16
msCAN12 Controller
16.1 Introduction
The msCAN12 is the specific implementation of the msCAN concept targeted for the Freescale M68HC12
Family of microcontrollers (MCU).
The module is a communication controller implementing the CAN 2.0 A/B protocol as defined in the
specification from Robert Bosch GmbH dated September 1991.
The CAN protocol was primarily, but not only, designed to be used as a vehicle serial data bus, meeting
the specific requirements of this field such as:
The msCAN12 simplifies the application software by utilizing an advanced buffer arrangement resulting
in a predictable real-time behavior.
16.2 External Pins
The msCAN12 uses two external pins, one input (RxCAN), and one output (TxCAN). The TxCAN output
pin represents the logic level on the CAN: 0 is for a dominant state, and 1 is for a recessive state.
RxCAN is on bit 0 of port CAN, and TxCAN is on bit 1. The remaining six pins of port CAN are controlled
by registers in the msCAN12 address space. See
16.12.16 msCAN12 Port CAN Data Direction
A typical CAN system with msCAN12 is shown in
Each CAN station is connected physically to the CAN bus lines through a transceiver chip. The
transceiver is capable of driving the large current needed for the CAN and has current protection against
defected CAN or defected stations.
16.3 Message Storage
msCAN12 facilitates a sophisticated message storage system which addresses the requirements of a
broad range of network applications.
Freescale Semiconductor
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Real-time processing
Reliable operation in the electromagnetic interference (EMI) environment of a vehicle
Cost effectiveness
Required bandwidth
M68HC12B Family Data Sheet, Rev. 9.1
Register.
Figure
16.12.14 msCAN12 Port CAN Control Register
16-1.
and
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