Motorola MPC564EVB Instrukcja Użytkownika Pobierz pdf (Strona 23)

MPC564EVB User’s Manual 1-13

Communication Ports

The CAN_A channel transceiver is provided by the Power Oak (PC33394). This transceiver has

software selectable options via the QSPI 0 channel which may communicate with the Power Oak

device. See the PC33394 data sheet for details. A 4.7K ohm pull-up is provided on the CAN_A

TX signal. Options S4 and S5 are provided near the Power Oak device to provide both MPC564

CAN_A and CAN_B channels for messaging on the Power Oak transceiver. If S4 and S5 are

connected, the B_RX option from the CAN_B port must be open.

B_RX Option Jumper

This option jumper enables the receive connection from the CAN_B port transceiver to the

MPC564 CAN B RX channel. The option allows the isolation of the CAN_B port transceiver RX

signal so that the user may use a different connection or transceiver for the MPC564 CAN B port.

C_RX and C_TX Option Jumpers

These options enable the CAN_C port transceiver RX and TX signals to be placed on the MPC564

MGPIO port CAN C signals. The CAN C operation on the MPC564 MGPIO port must be enabled

in software, see example source code. The MPC564 MGPIO Port bits 11 and 12 are effected along

with the MPC564EVB MIOS Port pins 30 and 31 respectfully.

B_EN and C_EN Option Pads, CN1 and CN2 Option Cut-Aways

These options provide access to the output enable and slew rate control of the respective CAN

transceiver. By default the transceivers are set to provide minimum slew rate (fast edge) and to be

constantly enabled for output. The configuration of the transceivers maybe modified for slew rate

or output control or both. Signaling CAN bus slew rate can be modified by increasing the value of

R66 and R67 for CAN_B and CAN_C respectfully. Opening the CN1 and CN2 away options for

CAN_B and CAN_C respectfully allows a MPC564 I/O port to be applied to the B_EN and C_EN

option pads to provide output control. A high level on the B_EN or C_EN would disable the

respective CAN transceiver output. See the PCA82C250 data sheet on the support CD for

additional information.

CAN_A, CAN_B, and CAN_C Port Connectors

These ports provide the CAN transceiver input and output connection to the CAN bus. No bias or

termination for the CAN bus is provided on the MPC564EVB board. If required the user must

install these components in the proto area or elsewhere on the CAN bus. Following are the pin

connections for the ports:

Pin 1 = CAN-Hi level signal

Pin 2 = CAN-Lo level signal

Pin 3 = Ground or common (this is required for proper return path on CAN bus)

Pin 4 = +5V supply for remote use or bias of CAN bus.

CAN_A, CAN_B, and CAN_C Port Termination Options

The RA1-3, RB1-3, and RC1-3 option locations provide the respective CAN A, B, or C port with

the ability to add bias and/or termination resistance. RA1, RB1, and RC1 locations provide low

bias (to ground) on the respective CAN Port CAN Hi signal. RA3, RB3, and RC3 locations provide

high bias (to +5V) on the respective CAN Port CAN Low signal. RA2, RB2, and RC2 locations

provide termination between the respective CAN Port CAN Hi and CAN Low signals.

Frees

cale Semiconductor,

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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