Freescale Semiconductor, Inc.
MSCAN Controller
The module is a communication controller implementing the CAN 2.0
A/B protocol as defined in the BOSCH specification 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:
real-time processing, reliable operation in the EMI environment of a
vehicle, cost-effectiveness and required bandwidth.
msCAN12 utilizes an advanced buffer arrangement resulting in a
predictable real-time behavior and simplifies the application software.
17.3 External Pins
The msCAN12 uses 2 external pins, 1 input (RxCAN) and 1 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, TxCAN is on bit 1. The remaining six pins
of Port CAN are controlled by registers in the msCAN12 address space
(see msCAN12 Port CAN Control Register (PCTLCAN) and msCAN12
Port CAN Data Direction Register (DDRCAN)).
A typical CAN system with msCAN12 is shown in Figure 17-1.
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 defective CAN
or defective stations.
Technical Data
MC68HC912DG128 — Rev 3.0
MSCAN Controller
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