Jackson Labs RSR GNSS Transcoder, User Manual

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RSR GNSS Transcoder™ User Manual
20 © 2017 Jackson Labs Technologies, Inc.
3.6.2 ISP#/SAASM Zeroize and RESET# Connector J3
The following table shows the optional ISP#/RESET# connector J3 pinout. Pulling RESET# low via
an open-drain transistor or via a switch to ground will cause the board to be reset. Holding ISP# low
during the reset event will cause the processor to go into In-System-Programming (ISP) mode as
explained in Chapter 5. Both signals should be left floating during normal operation. Two metal
tweezers are commonly used to momentarily reset the board while holding the ISP pin low.
Pin 1 of connector J3 has an alternate function as a Zeroize command input for units connected to
external SAASM GPS receivers (Rockwell Collins MicroGRAM, GB-GRAM, RSR Puck, etc).
Pulling this pin to ground during normal operation will cause the unit to send a SAASM Key Zeroize
serial command to the externally connected SAASM GPS receiver. This pin can thus be connected to
an external switch to ground, and used to initialize ISP mode, as well as an emergency zeroize button
for the SAASM GPS receiver. This pin has no effect during normal operation when the unit is
connected to a commercial GNSS receiver and operating normally.
J4-9 ISP#, SAASM
Zeroize# Processor In System
Programming pin.
SAASM Zeroize input.
Pulling this pin to ground
during power-on or during a
Reset event will cause the
processor to go into ISP
mode.
Alternate function is to send a
Zeroize command to the
externally connected SAASM
GPS receiver when
pulled-low during normal
operation. Leave floating
normally.
J4-10 GND System Ground Ground
J4-11 +5.4V IN/OUT Dual-Purpose power
pin:
Power Output to
external GNSS
Alternatively
high-efficiency power
input from external
power source Follows USB power supply
voltage for USB powered
applications. Has 5.4V output
on it for external GNSS
receiver if Prime Power input
pin 2 of J4 is used.
Can alternatively be used as
a high-efficiency 2.7V to 5.5V
Input to board if neither Prime
Power nor USB power is
applied.
J4-12 10MHz OUT 10MHz Buffered
output from internal
Oscillator 3.3V CMOS 10MHz buffered
output from internal
Oscillator. Must be
software-enabled via SCPI
command.