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                               Button example program
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Copyright(C) Redpine Signals 2016
All rights reserved by Redpine Signals.

This program should be used on your own responsibility.
Redpine Signals assumes no responsibility for any losses
incurred by customers or third parties arising from the use of this file. 

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Function description:
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The  Button example will rise the button interrupt  .

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Environment
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Test Board:
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Smark EVK 

Assistance software:
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None

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Usage Procedure:
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compile and run the application.Give the button range voltages through power supply to UULPSS_GPIO(2):J2.25.
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Pass criteria:
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Keep a break point at Button IRQ (line 77).Add button_number variable to watch window to see the 
button value.you can see the button number through any serial terminal  prints.
Note: Enable DEBUG_UART macro to see the voltage value on serial terminal.
      Connect a USB cable to J21 to see the UART print
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Note: 1) button ranges are as below in this example
                     Button-1 :2.21v - 1.94v
                     Button-2 :1.76v - 1.55v
                     Button-3 :1.39v - 1.26v
      2)UULP_GPIO_2 is the only pin to conifigure as the input pin for Button. 
      3)While using the Button ,UULPSS_GPIO_2 should not use for other configurations.
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