pot.nc

传感器网络中的嵌入式操作系统源代码

// $Id: Pot.nc,v 1.2.14.4 2003/08/26 09:08:13 cssharp Exp $

/*									tab:4
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 * Copyright (c) 2002-2003 Intel Corporation
 * All rights reserved.
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/*
 * Authors:		Jason Hill, David Gay, Philip Levis
 * Date last modified:  8/20/02
 */

/**
 * The Pot interface allows users to adjust the potentiometer on the input
 * to the RFM radio which controls the RF transmit power or connectivity range.
 * The interface controls the potentiometer, rather than the signal strength,
 * so the settings may be a bit counterintuitive: the low potentiometer
 * settings correspond to high transmission power, and high potentiometer
 * settings correspond to low transmission power. Valid range depends on the
 * platform being used:  
 * <ul>
 * <li> <bold>Mica</bold> -- parameters range from 0 to 99; the actual
 * transmission range is heavily dependent on the antenna. With the built-in
 * antenna one can generally expect the range from 1 inch to 15 feet; with the
 * external antenna the range is from  1 foot to 100 feet.
 * <li> <bold>Rene</bold> -- parameters range from 20 to 77, though the exact
 * upper bound depends heavily on battery voltage. The exact range achieved
 * depends heavily on the battery used, but covers roughly the same range as
 * Mica (from 1 to 100 feet). <em> Let us emphasize this again: The exact low
 * transmission power bound for the Rene is dependent on battery voltage; it
 * is VERY difficult to get a reliable short range communication over an
 * extended time period without active control of the potentiometer. </em>
 * </ul> 
 * <em>Note:</em> the transmission power is NOT linear with respect to the
 * potentiometer setting; see mote schematics and RFM TR1000 manual for more
 * information. </p>
 * <em>Note:</em> any change to the potentiometer value will cause LEDs to
 * blink. This behavior is normal, expected, and unavoidable; at the end of
 * a potentiometer setting operation you may be left with an inconsistent LED
 * state, though the functions provided by the LED component will continue to
 * work correctly. 
 * @author Jason Hill
 * @author David Gay
 * @author Philip Levis
 */

interface Pot {
    /** 
     * Initialize the potentiometer and set it to a specified value. 
     * @param initialSetting The initial value for setting of the signal
     * strength; see above for valid ranges and communication radii achieved
     * with them. 
     * @return Returns SUCCESS upon successful initialization. 
     */
  command result_t init(uint8_t initialSetting);

    /**
     * Set the potentiometer value
     * @param setting The new value of the potentiometer. 
     * @return Returns SUCCESS if the setting was successful.  The operation
     * returns FAIL if the component has not been initialized or the desired
     * setting is outside of the valid range. 
     */ 
  command result_t set(uint8_t setting);

    /** 
     * Increment the potentiometer value by 1. This function proves to be
     * quite useful in active potentiometer control scenarios.
     * @return Returns SUCCESS if the increment was successful. Returns FAIL
     * if the component has not been initialized or if the potentiometer
     * cannot be incremented further. 
     */ 
  command result_t increase();

    /** 
     * Decrement the potentiometer value by 1. This function proves to be
     * quite useful in active potentiometer control scenarios.
     * @return Returns SUCCESS if the decrement was successful. Returns FAIL
     * if the component has not been initialized or if the potentiometer
     * cannot be decremented further. 
     */ 
  command result_t decrease();

    /**
     * Return the current setting of the potentiometer. 
     * @return An unsigned 8-bit value denoting the current setting of the
     * potentiometer. 
     */
  command uint8_t get();
}