Freescale Semiconductor Demonstration Board for Freescale MC9S12XHY256 Microcontroller DEMO9S12XHY256 DEMO9S12XHY256 Manual De Usuario
Los códigos de productos
DEMO9S12XHY256
Freescale’s Scalable Controller Area Network (S12MSCANV3)
MC9S12XHY-Family Reference Manual, Rev. 1.04
342
Freescale Semiconductor
11.2
External Signal Description
The MSCAN uses two external pins.
NOTE
On MCUs with an integrated CAN physical interface (transceiver) the
MSCAN interface is connected internally to the transceiver interface. In
these cases the external availability of signals TXCAN and RXCAN is
optional.
MSCAN interface is connected internally to the transceiver interface. In
these cases the external availability of signals TXCAN and RXCAN is
optional.
11.2.1
RXCAN — CAN Receiver Input Pin
RXCAN is the MSCAN receiver input pin.
11.2.2
TXCAN — CAN Transmitter Output Pin
TXCAN is the MSCAN transmitter output pin. The TXCAN output pin represents the logic level on the
CAN bus:
CAN bus:
0 = Dominant state
1 = Recessive state
1 = Recessive state
11.2.3
CAN System
A typical CAN system with MSCAN is shown in
. Each CAN station is connected physically
to the CAN bus lines through a transceiver device. The transceiver is capable of driving the large current
needed for the CAN bus and has current protection against defective CAN or defective stations.
needed for the CAN bus and has current protection against defective CAN or defective stations.
Figure 11-2. CAN System
CAN Bus
CAN Controller
(MSCAN)
Transceiver
CAN node 1
CAN node 2
CAN node n
CANL
CANH
MCU
TXCAN
RXCAN