Cmos Level I/O; Top-View, P1502 Expansion 16-Pin Header - Novatel OEM6 Series User Manual

Pin
1 ETH_RD-
2 ETH_RD+
3 3V3 (for Ethernet
magnetics center tap)
4 ETH_TD+
5 ETH_TD-
6 3V3 (for Ethernet
magnetics center tap)
7 LED_A
8 LED_B
9 GND
10 CAN1TX
11 CAN1RX
12 CAN2TX
13 CAN2RX
14 Reserved
15 VBUS
16 GND
C.1.2

CMOS Level I/O

The OEM628 provides a number of 2.7 V (3.3 V-compatible) CMOS level I/O pins for status indication
and timing. These I/O include:
• PPS: Pulse-Per-Second (software configurable to other rates)
• VARF: Variable Frequency (a software configurable clock output)
• ERROR: Error indication
• PV: Position Valid (used to indicate when the receiver has calculated a valid position)
• EVENT1 and EVENT2: Event inputs (active high by default with configurable polarity)
• USERIO1 and USERIO2: User GPIO (available through NovAtel's API)
These I/O require additional ESD protection if they are routed to connectors. Some users may require
additional drive strength on the PPS signal. The figure below shows a suitable buffer that may be used.
R103 in the schematic may be used to limit the drive strength of the PPS output if required. This buffer
has a propagation delay of approximately 5 to 6 nanoseconds.
The same ESD protection circuit shown below should be used on any OEM628 CMOS level signal that
will be routed to an enclosure connector. The ferrite bead and small value capacitor provide some
immunity to electrostatic discharge events, but also serve to reduce radiated and conducted emissions
from the enclosure.
OEM6 Family Installation and Operation User Manual Rev 7
Figure 62: Top-view, P1502 Expansion 16-Pin Header
Pin 2
Pin 1
Signal
Input
Input
Output
Output
Output
Output
Output
Output
REF
Output
Input
Output
Input
Input
Input
REF
Pin 2
Pin 24 Pin 16
Pin 23 Pin 15
Pin 1
Type
Ethernet Rx-
Ethernet Rx+
Rx centre tap power for Ethernet
magnetics
Ethernet Tx+
Ethernet Tx-
Tx center tap power for Ethernet
magnetics
Activity/Link
100 BT
GND
CAN1TX
CAN1RX
CAN2TX
CAN2RX
UID
VBUS
GND
Description
131