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Chapter 3 New for OEM7 – Hardware
3.5 Receiver Card Interface Examples
The OEM7 receiver cards provide a number of 3.3V CMOS-level I/O pins for status indication and
timing:
COMx: CMOS-level UART ports
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Ethernet: 10/100 Ethernet port
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CAN1 and CAN2: CMOS-level CAN ports (external CAN transceivers required)
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PPS: Output pulse providing time reference signal (software configurable output rate,
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defaults to 1 Pulse Per Second)
EVENTx_OUT: Variable Frequency output (a software-configurable clock output similar to
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PPS, off by default). (The EVENT1_OUT signal may also be referred to as an VARF.)
PV: Position Valid (This signal drives high when the receiver has calculated a valid position)
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EVENTx_IN: Event inputs (with configurable polarity)
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USERIO: A user defined general purpose input or output (OEM729 only)
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These I/O require additional ESD protection if they are to be routed to enclosure connectors. A
protection circuit similar to the following examples must be used on any OEM7 CMOS-level sig-
nals 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.
3.5.1 EVENT_IN, EVENT_OUT and PPS Signal Protection
The following schematic shows appropriate signal conditioning for EVENT_IN (MKI), EVENT_OUT
(VARF) and PPS (TIMEMARK) signals.
OEM6 to OEM7 Integration Guide v1
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