Globalstar STX3, Руководство пользователя, Страница: 16 / 32

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DEV KIT POWER CIRCUITRY
The Dev Kit consists of two buck/boost switching power supplies that support voltages from 1.8V-5.25V. One of
buck/boost power supplies is located on the Transmitter board, and is dedicated to supplying power to the RF signal
on the STX3 module. The other buck/boost power supply is located on the Main board and supplies power to the
Main board electronics including the digital supply for the STX3 module.
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STX3 RF Power Supply - The RF power supply is dedicated to the VRF pin on the STX3 module. The power
supply is enabled and disabled by the STX3 module. This is a buck/boost supply and is used in a buck (step-
down) configuration on the Dev Kit. The input voltage to the power supply is 5V with an output voltage of 3.3V
and supports peak output current up to 1A. The power supply will maintain an output voltage of 3.3V even with
input voltages down to 1.8V.
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Main Board Power Supply - The main power supply is a buck/boost switching supply located on the Main board.
On the Dev Kit, the power supply supports an input voltage from 1.8V to 5.25V with an output voltage of 3.3V
and peak output current of 1A. The main power supply supports everything on the Dev Kit except the STX3 RF
power supply. The power supply also includes a 2 pin header (J6) used to temporarily disable power to the Dev
Kit board without removing the USB cable. Applying the shunt across J6 will disable the main power supply.
LED’S
The Dev Kit includes four LED’s with three of them located on the Main board and one located on the
Transmitter board.
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Main Board - Green LED LD2 indicates the main power supply is enabled. The red LED LD3 is connected to the
processor and will be enabled while the STX3 is establishing satellite transmission. The other green “heartbeat”
LED LD4 will continue to flash slowly to indicate the processor firmware is running. The green heartbeat LED
and red STX3 satellite transmission LED are controlled by the firmware on the processor.
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Transmitter Board - The green LED LD1 indicates the RF power supply is enabled and will be enabled for
approximately 1 second.
BUTTONS
The Dev Kit has two tactile momentary buttons that are connected to the Nordic processor.
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User Button - The user button, SW1, is connected to GPIO P0.22 on Nordic processor and is programmed to
initiate a STX3 test message packet transmission. This GPIO pin can be reconfigured in the firmware to support
some other function.
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Reset Button - This button, SW2, resets the Nordic processor, and is not reconfigurable.