Can Controller Ports - Novatel OEM6 Integration Manual

Chapter 3 New for OEM7 – Hardware
A combination of a series ferrite bead and small-value shunt capacitor is recommended on any
RS232/RS422 lines that leave the enclosure (similar to the arrangement used on the I/O ports
and CAN interfaces). Many of the available transceivers provide protection for ESD events to
±15kV – if additional protection is required, an external TVS with a working voltage of ±15V to
±25V will be required.

3.5.4 CAN Controller Ports

OEM7 receivers provide 3.3V CMOS-level CAN controller ports. An external CAN transceiver is
required. The following figure shows a typical CAN transceiver implementation.
The combination of ferrite beads and small-value capacitors are not necessarily required but
may provide improved EMI performance. A low-capacitance TVS device is shown on the schem-
atic to provide ESD protection.
The 120Ω termination resistor should only be used when the CAN device is used at one end of
the CAN bus. Multiple terminations along the length of the CAN bus will degrade performance for
all CAN devices on that bus.
The slew rate adjustment resistor (R2) value shown sets the slew rate for applications for SAE
J1939 agricultural applications. Other applications may require a different slew rate. Refer to
the transceiver datasheet for more information.
1
These pins are multiplexed with other signals and may not be available when certain features are enabled. See
P1701 Main Connector 20-Pin Header on page 190 for more information.
OEM6 to OEM7 Integration Guide v1
Figure 6: OEM7 CAN Transceiver Example
Table 67: CAN Transceiver Pin Designation
OEM719
Connector P1701
1
CAN1TX 7
1
6
CAN1RX
CAN2TX 20
CAN2RX 8
OEM729 OEM7700
P1803 P2001
10 36
11 38
12 37
13 35
167