File content as of revision 1:8fc901e8846f:

/*
 Copyright (C) 2011 J. Coliz <maniacbug@ymail.com>

 This program is free software; you can redistribute it and/or
 modify it under the terms of the GNU General Public License
 version 2 as published by the Free Software Foundation.
 */

/**
 * @file RF24.h
 *
 * Class declaration for RF24 and helper enums
 */

#ifndef __RF24_H__
#define __RF24_H__

#include <RF24_config.h>

/**
 * Power Amplifier level.
 *
 * For use with setPALevel()
 */
typedef enum { RF24_PA_MIN = 0,RF24_PA_LOW, RF24_PA_HIGH, RF24_PA_MAX, RF24_PA_ERROR } rf24_pa_dbm_e ;

/**
 * Data rate.  How fast data moves through the air.
 *
 * For use with setDataRate()
 */
typedef enum { RF24_1MBPS = 0, RF24_2MBPS, RF24_250KBPS } rf24_datarate_e;

/**
 * CRC Length.  How big (if any) of a CRC is included.
 *
 * For use with setCRCLength()
 */
typedef enum { RF24_CRC_DISABLED = 0, RF24_CRC_8, RF24_CRC_16 } rf24_crclength_e;

/**
 * Driver for nRF24L01(+) 2.4GHz Wireless Transceiver
 */

class RF24
{
private:
    DigitalOut ce_pin; /**< "Chip Enable" pin, activates the RX or TX role */
    DigitalOut csn_pin; /**< SPI Chip select */
    bool wide_band; /* 2Mbs data rate in use? */
    bool p_variant; /* False for RF24L01 and true for RF24L01P */
    uint8_t payload_size; /**< Fixed size of payloads */
    bool ack_payload_available; /**< Whether there is an ack payload waiting */
    bool dynamic_payloads_enabled; /**< Whether dynamic payloads are enabled. */
    uint8_t ack_payload_length; /**< Dynamic size of pending ack payload. */
    uint64_t pipe0_reading_address; /**< Last address set on pipe 0 for reading. */

    SPI spi;

protected:
    /**
     * @name Low-level internal interface.
     *
     *  Protected methods that address the chip directly.  Regular users cannot
     *  ever call these.  They are documented for completeness and for developers who
     *  may want to extend this class.
     */
    /**@{*/

    /**
     * Set chip select pin
     *
     * Running SPI bus at PI_CLOCK_DIV2 so we don't waste time transferring data
     * and best of all, we make use of the radio's FIFO buffers. A lower speed
     * means we're less likely to effectively leverage our FIFOs and pay a higher
     * AVR runtime cost as toll.
     *
     * @param mode HIGH to take this unit off the SPI bus, LOW to put it on
     */
    void csn(int mode);

    /**
     * Set chip enable
     *
     * @param level HIGH to actively begin transmission or LOW to put in standby.  Please see data sheet
     * for a much more detailed description of this pin.
     */
    void ce(int level);

    /**
     * Read a chunk of data in from a register
     *
     * @param reg Which register. Use constants from nRF24L01.h
     * @param buf Where to put the data
     * @param len How many bytes of data to transfer
     * @return Current value of status register
     */
    uint8_t read_register(uint8_t reg, uint8_t* buf, uint8_t len);

    /**
     * Read single byte from a register
     *
     * @param reg Which register. Use constants from nRF24L01.h
     * @return Current value of register @p reg
     */
    uint8_t read_register(uint8_t reg);

    /**
     * Write a chunk of data to a register
     *
     * @param reg Which register. Use constants from nRF24L01.h
     * @param buf Where to get the data
     * @param len How many bytes of data to transfer
     * @return Current value of status register
     */
    uint8_t write_register(uint8_t reg, const uint8_t* buf, uint8_t len);

    /**
     * Write a single byte to a register
     *
     * @param reg Which register. Use constants from nRF24L01.h
     * @param value The new value to write
     * @return Current value of status register
     */
    uint8_t write_register(uint8_t reg, uint8_t value);

    /**
     * Write the transmit payload
     *
     * The size of data written is the fixed payload size, see getPayloadSize()
     *
     * @param buf Where to get the data
     * @param len Number of bytes to be sent
     * @return Current value of status register
     */
    uint8_t write_payload(const void* buf, uint8_t len);

    /**
     * Read the receive payload
     *
     * The size of data read is the fixed payload size, see getPayloadSize()
     *
     * @param buf Where to put the data
     * @param len Maximum number of bytes to read
     * @return Current value of status register
     */
    uint8_t read_payload(void* buf, uint8_t len);

    /**
     * Empty the receive buffer
     *
     * @return Current value of status register
     */
    uint8_t flush_rx(void);

    /**
     * Empty the transmit buffer
     *
     * @return Current value of status register
     */
    uint8_t flush_tx(void);

    /**
     * Retrieve the current status of the chip
     *
     * @return Current value of status register
     */
    uint8_t get_status(void);

    /**
     * Decode and print the given status to stdout
     *
     * @param status Status value to print
     *
     * @warning Does nothing if stdout is not defined.  See fdevopen in stdio.h
     */
    void print_status(uint8_t status);

    /**
     * Decode and print the given 'observe_tx' value to stdout
     *
     * @param value The observe_tx value to print
     *
     * @warning Does nothing if stdout is not defined.  See fdevopen in stdio.h
     */
    void print_observe_tx(uint8_t value);

    /**
     * Print the name and value of an 8-bit register to stdout
     *
     * Optionally it can print some quantity of successive
     * registers on the same line.  This is useful for printing a group
     * of related registers on one line.
     *
     * @param name Name of the register
     * @param reg Which register. Use constants from nRF24L01.h
     * @param qty How many successive registers to print
     */
    void print_byte_register(const char* name, uint8_t reg, uint8_t qty = 1);

    /**
     * Print the name and value of a 40-bit address register to stdout
     *
     * Optionally it can print some quantity of successive
     * registers on the same line.  This is useful for printing a group
     * of related registers on one line.
     *
     * @param name Name of the register
     * @param reg Which register. Use constants from nRF24L01.h
     * @param qty How many successive registers to print
     */
    void print_address_register(const char* name, uint8_t reg, uint8_t qty = 1);

    /**
     * Turn on or off the special features of the chip
     *
     * The chip has certain 'features' which are only available when the 'features'
     * are enabled.  See the datasheet for details.
     */
    void toggle_features(void);
    /**@}*/

public:
    /**
     * @name Primary public interface
     *
     *  These are the main methods you need to operate the chip
     */
    /**@{*/

    /**
     * Constructor
     *
     * Creates a new instance of this driver.  Before using, you create an instance
     * and send in the unique pins that this chip is connected to.
     *
     * @param mosi The pin attached to MOSI on the RF module
     * @param miso The pin attached to MISO on the RF module
     * @param sck The pin attached to SCK on the RF module
     * @param _cepin The pin attached to Chip Enable on the RF module
     * @param _csnpin The pin attached to Chip Select
     */
    RF24(PinName mosi, PinName miso, PinName sck, PinName _cepin, PinName _csnpin);

    /**
     * Begin operation of the chip
     *
     * Call this in setup(), before calling any other methods.
     */
    void begin(void);

    /**
     * Start listening on the pipes opened for reading.
     *
     * Be sure to call openReadingPipe() first.  Do not call write() while
     * in this mode, without first calling stopListening().  Call
     * isAvailable() to check for incoming traffic, and read() to get it.
     */
    void startListening(void);

    /**
     * Stop listening for incoming messages
     *
     * Do this before calling write().
     */
    void stopListening(void);

    /**
     * Write to the open writing pipe
     *
     * Be sure to call openWritingPipe() first to set the destination
     * of where to write to.
     *
     * This blocks until the message is successfully acknowledged by
     * the receiver or the timeout/retransmit maxima are reached.  In
     * the current configuration, the max delay here is 60ms.
     *
     * The maximum size of data written is the fixed payload size, see
     * getPayloadSize().  However, you can write less, and the remainder
     * will just be filled with zeroes.
     *
     * @param buf Pointer to the data to be sent
     * @param len Number of bytes to be sent
     * @return True if the payload was delivered successfully false if not
     */
    bool write( const void* buf, uint8_t len );

    /**
     * Test whether there are bytes available to be read
     *
     * @return True if there is a payload available, false if none is
     */
    bool available(void);

    /**
     * Read the payload
     *
     * Return the last payload received
     *
     * The size of data read is the fixed payload size, see getPayloadSize()
     *
     * @note I specifically chose 'void*' as a data type to make it easier
     * for beginners to use.  No casting needed.
     *
     * @param buf Pointer to a buffer where the data should be written
     * @param len Maximum number of bytes to read into the buffer
     * @return True if the payload was delivered successfully false if not
     */
    bool read( void* buf, uint8_t len );

    /**
     * Open a pipe for writing
     *
     * Only one pipe can be open at once, but you can change the pipe
     * you'll listen to.  Do not call this while actively listening.
     * Remember to stopListening() first.
     *
     * Addresses are 40-bit hex values, e.g.:
     *
     * @code
     *   openWritingPipe(0xF0F0F0F0F0);
     * @endcode
     *
     * @param address The 40-bit address of the pipe to open.  This can be
     * any value whatsoever, as long as you are the only one writing to it
     * and only one other radio is listening to it.  Coordinate these pipe
     * addresses amongst nodes on the network.
     */
    void openWritingPipe(uint64_t address);

    /**
     * Open a pipe for reading
     *
     * Up to 6 pipes can be open for reading at once.  Open all the
     * reading pipes, and then call startListening().
     *
     * @see openWritingPipe
     *
     * @warning Pipes 1-5 should share the first 32 bits.
     * Only the least significant byte should be unique, e.g.
     * @code
     *   openReadingPipe(1,0xF0F0F0F0AA);
     *   openReadingPipe(2,0xF0F0F0F066);
     * @endcode
     *
     * @warning Pipe 0 is also used by the writing pipe.  So if you open
     * pipe 0 for reading, and then startListening(), it will overwrite the
     * writing pipe.  Ergo, do an openWritingPipe() again before write().
     *
     * @todo Enforce the restriction that pipes 1-5 must share the top 32 bits
     *
     * @param number Which pipe# to open, 0-5.
     * @param address The 40-bit address of the pipe to open.
     */
    void openReadingPipe(uint8_t number, uint64_t address);

    /**@}*/
    /**
     * @name Optional Configurators
     *
     *  Methods you can use to get or set the configuration of the chip.
     *  None are required.  Calling begin() sets up a reasonable set of
     *  defaults.
     */
    /**@{*/
    /**
     * Set the number and delay of retries upon failed submit
     *
     * @param delay How long to wait between each retry, in multiples of 250us,
     * max is 15.  0 means 250us, 15 means 4000us.
     * @param count How many retries before giving up, max 15
     */
    void setRetries(uint8_t delay, uint8_t count);

    /**
     * Set RF communication channel
     *
     * @param channel Which RF channel to communicate on, 0-127
     */
    void setChannel(uint8_t channel);

    /**
     * Set Static Payload Size
     *
     * This implementation uses a pre-stablished fixed payload size for all
     * transmissions.  If this method is never called, the driver will always
     * transmit the maximum payload size (32 bytes), no matter how much
     * was sent to write().
     *
     * @todo Implement variable-sized payloads feature
     *
     * @param size The number of bytes in the payload
     */
    void setPayloadSize(uint8_t size);

    /**
     * Get Static Payload Size
     *
     * @see setPayloadSize()
     *
     * @return The number of bytes in the payload
     */
    uint8_t getPayloadSize(void);

    /**
     * Get Dynamic Payload Size
     *
     * For dynamic payloads, this pulls the size of the payload off
     * the chip
     *
     * @return Payload length of last-received dynamic payload
     */
    uint8_t getDynamicPayloadSize(void);

    /**
     * Enable custom payloads on the acknowledge packets
     *
     * Ack payloads are a handy way to return data back to senders without
     * manually changing the radio modes on both units.
     *
     * @see examples/pingpair_pl/pingpair_pl.pde
     */
    void enableAckPayload(void);

    /**
     * Enable dynamically-sized payloads
     *
     * This way you don't always have to send large packets just to send them
     * once in a while.  This enables dynamic payloads on ALL pipes.
     *
     * @see examples/pingpair_pl/pingpair_dyn.pde
     */
    void enableDynamicPayloads(void);

    /**
     * Determine whether the hardware is an nRF24L01+ or not.
     *
     * @return true if the hardware is nRF24L01+ (or compatible) and false
     * if its not.
     */
    bool isPVariant(void) ;

    /**
     * Enable or disable auto-acknowlede packets
     *
     * This is enabled by default, so it's only needed if you want to turn
     * it off for some reason.
     *
     * @param enable Whether to enable (true) or disable (false) auto-acks
     */
    void setAutoAck(bool enable);

    /**
     * Enable or disable auto-acknowlede packets on a per pipeline basis.
     *
     * AA is enabled by default, so it's only needed if you want to turn
     * it off/on for some reason on a per pipeline basis.
     *
     * @param pipe Which pipeline to modify
     * @param enable Whether to enable (true) or disable (false) auto-acks
     */
    void setAutoAck( uint8_t pipe, bool enable ) ;

    /**
     * Set Power Amplifier (PA) level to one of four levels.
     * Relative mnemonics have been used to allow for future PA level
     * changes. According to 6.5 of the nRF24L01+ specification sheet,
     * they translate to: RF24_PA_MIN=-18dBm, RF24_PA_LOW=-12dBm,
     * RF24_PA_MED=-6dBM, and RF24_PA_HIGH=0dBm.
     *
     * @param level Desired PA level.
     */
    void setPALevel( rf24_pa_dbm_e level ) ;

    /**
     * Fetches the current PA level.
     *
     * @return Returns a value from the rf24_pa_dbm_e enum describing
     * the current PA setting. Please remember, all values represented
     * by the enum mnemonics are negative dBm. See setPALevel for
     * return value descriptions.
     */
    rf24_pa_dbm_e getPALevel( void ) ;

    /**
     * Set the transmission data rate
     *
     * @warning setting RF24_250KBPS will fail for non-plus units
     *
     * @param speed RF24_250KBPS for 250kbs, RF24_1MBPS for 1Mbps, or RF24_2MBPS for 2Mbps
     * @return true if the change was successful
     */
    bool setDataRate(rf24_datarate_e speed);

    /**
     * Fetches the transmission data rate
     *
     * @return Returns the hardware's currently configured datarate. The value
     * is one of 250kbs, RF24_1MBPS for 1Mbps, or RF24_2MBPS, as defined in the
     * rf24_datarate_e enum.
     */
    rf24_datarate_e getDataRate( void ) ;

    /**
     * Set the CRC length
     *
     * @param length RF24_CRC_8 for 8-bit or RF24_CRC_16 for 16-bit
     */
    void setCRCLength(rf24_crclength_e length);

    /**
     * Get the CRC length
     *
     * @return RF24_DISABLED if disabled or RF24_CRC_8 for 8-bit or RF24_CRC_16 for 16-bit
     */
    rf24_crclength_e getCRCLength(void);

    /**
     * Disable CRC validation
     *
     */
    void disableCRC( void ) ;

    /**@}*/
    /**
     * @name Advanced Operation
     *
     *  Methods you can use to drive the chip in more advanced ways
     */
    /**@{*/

    /**
     * Print a giant block of debugging information to stdout
     *
     * @warning Does nothing if stdout is not defined.  See fdevopen in stdio.h
     */
    void printDetails(void);

    /**
     * Enter low-power mode
     *
     * To return to normal power mode, either write() some data or
     * startListening, or powerUp().
     */
    void powerDown(void);

    /**
     * Leave low-power mode - making radio more responsive
     *
     * To return to low power mode, call powerDown().
     */
    void powerUp(void) ;

    /**
     * Test whether there are bytes available to be read
     *
     * Use this version to discover on which pipe the message
     * arrived.
     *
     * @param[out] pipe_num Which pipe has the payload available
     * @return True if there is a payload available, false if none is
     */
    bool available(uint8_t* pipe_num);

    /**
     * Non-blocking write to the open writing pipe
     *
     * Just like write(), but it returns immediately. To find out what happened
     * to the send, catch the IRQ and then call whatHappened().
     *
     * @see write()
     * @see whatHappened()
     *
     * @param buf Pointer to the data to be sent
     * @param len Number of bytes to be sent
     * @return True if the payload was delivered successfully false if not
     */
    void startWrite( const void* buf, uint8_t len );

    /**
     * Write an ack payload for the specified pipe
     *
     * The next time a message is received on @p pipe, the data in @p buf will
     * be sent back in the acknowledgement.
     *
     * @warning According to the data sheet, only three of these can be pending
     * at any time.  I have not tested this.
     *
     * @param pipe Which pipe# (typically 1-5) will get this response.
     * @param buf Pointer to data that is sent
     * @param len Length of the data to send, up to 32 bytes max.  Not affected
     * by the static payload set by setPayloadSize().
     */
    void writeAckPayload(uint8_t pipe, const void* buf, uint8_t len);

    /**
     * Determine if an ack payload was received in the most recent call to
     * write().
     *
     * Call read() to retrieve the ack payload.
     *
     * @warning Calling this function clears the internal flag which indicates
     * a payload is available.  If it returns true, you must read the packet
     * out as the very next interaction with the radio, or the results are
     * undefined.
     *
     * @return True if an ack payload is available.
     */
    bool isAckPayloadAvailable(void);

    /**
     * Call this when you get an interrupt to find out why
     *
     * Tells you what caused the interrupt, and clears the state of
     * interrupts.
     *
     * @param[out] tx_ok The send was successful (TX_DS)
     * @param[out] tx_fail The send failed, too many retries (MAX_RT)
     * @param[out] rx_ready There is a message waiting to be read (RX_DS)
     */
    void whatHappened(bool& tx_ok,bool& tx_fail,bool& rx_ready);

    /**
     * Test whether there was a carrier on the line for the
     * previous listening period.
     *
     * Useful to check for interference on the current channel.
     *
     * @return true if was carrier, false if not
     */
    bool testCarrier(void);

    /**
     * Test whether a signal (carrier or otherwise) greater than
     * or equal to -64dBm is present on the channel. Valid only
     * on nRF24L01P (+) hardware. On nRF24L01, use testCarrier().
     *
     * Useful to check for interference on the current channel and
     * channel hopping strategies.
     *
     * @return true if signal => -64dBm, false if not
     */
    bool testRPD(void) ;

    /**
     * Test whether this is a real radio, or a mock shim for
     * debugging.  Setting either pin to 0xff is the way to
     * indicate that this is not a real radio.
     *
     * @return true if this is a legitimate radio
     */
    bool isValid() {
        return ce_pin != 0xff && csn_pin != 0xff;
    }
    
    /**@}*/
};

/**
 * @example GettingStarted.pde
 *
 * This is an example which corresponds to my "Getting Started" blog post:
 * <a style="text-align:center" href="http://maniacbug.wordpress.com/2011/11/02/getting-started-rf24/">Getting Started with nRF24L01+ on Arduino</a>.
 *
 * It is an example of how to use the RF24 class.  Write this sketch to two
 * different nodes.  Put one of the nodes into 'transmit' mode by connecting
 * with the serial monitor and sending a 'T'.  The ping node sends the current
 * time to the pong node, which responds by sending the value back.  The ping
 * node can then see how long the whole cycle took.
 */

/**
 * @example nordic_fob.pde
 *
 * This is an example of how to use the RF24 class to receive signals from the
 * Sparkfun Nordic FOB.  See http://www.sparkfun.com/products/8602 .
 * Thanks to Kirk Mower for providing test hardware.
 */

/**
 * @example led_remote.pde
 *
 * This is an example of how to use the RF24 class to control a remote
 * bank of LED's using buttons on a remote control.
 *
 * Every time the buttons change on the remote, the entire state of
 * buttons is send to the led board, which displays the state.
 */

/**
 * @example pingpair.pde
 *
 * This is an example of how to use the RF24 class.  Write this sketch to two
 * different nodes, connect the role_pin to ground on one.  The ping node sends
 * the current time to the pong node, which responds by sending the value back.
 * The ping node can then see how long the whole cycle took.
 */

/**
 * @example pingpair_maple.pde
 *
 * This is an example of how to use the RF24 class on the Maple.  For a more
 * detailed explanation, see my blog post:
 * <a href="http://maniacbug.wordpress.com/2011/12/14/nrf24l01-running-on-maple-3/">nRF24L01+ Running on Maple</a>
 *
 * It will communicate well to an Arduino-based unit as well, so it's not for only Maple-to-Maple communication.
 *
 * Write this sketch to two different nodes,
 * connect the role_pin to ground on one.  The ping node sends the current time to the pong node,
 * which responds by sending the value back.  The ping node can then see how long the whole cycle
 * took.
 */

/**
 * @example starping.pde
 *
 * This sketch is a more complex example of using the RF24 library for Arduino.
 * Deploy this on up to six nodes.  Set one as the 'pong receiver' by tying the
 * role_pin low, and the others will be 'ping transmit' units.  The ping units
 * unit will send out the value of millis() once a second.  The pong unit will
 * respond back with a copy of the value.  Each ping unit can get that response
 * back, and determine how long the whole cycle took.
 *
 * This example requires a bit more complexity to determine which unit is which.
 * The pong receiver is identified by having its role_pin tied to ground.
 * The ping senders are further differentiated by a byte in eeprom.
 */

/**
 * @example pingpair_pl.pde
 *
 * This is an example of how to do two-way communication without changing
 * transmit/receive modes.  Here, a payload is set to the transmitter within
 * the Ack packet of each transmission.  Note that the payload is set BEFORE
 * the sender's message arrives.
 */

/**
 * @example pingpair_irq.pde
 *
 * This is an example of how to user interrupts to interact with the radio.
 * It builds on the pingpair_pl example, and uses ack payloads.
 */

/**
 * @example pingpair_sleepy.pde
 *
 * This is an example of how to use the RF24 class to create a battery-
 * efficient system.  It is just like the pingpair.pde example, but the
 * ping node powers down the radio and sleeps the MCU after every
 * ping/pong cycle.
 */

/**
 * @example scanner.pde
 *
 * Example to detect interference on the various channels available.
 * This is a good diagnostic tool to check whether you're picking a
 * good channel for your application.
 *
 * Inspired by cpixip.
 * See http://arduino.cc/forum/index.php/topic,54795.0.html
 */

/**
 * @mainpage Driver for nRF24L01(+) 2.4GHz Wireless Transceiver
 *
 * @section Goals Design Goals
 *
 * This library is designed to be...
 * @li Maximally compliant with the intended operation of the chip
 * @li Easy for beginners to use
 * @li Consumed with a public interface that's similiar to other Arduino standard libraries
 *
 * @section News News
 *
 * NOW COMPATIBLE WITH ARDUINO 1.0 - The 'master' branch and all examples work with both Arduino 1.0 and earlier versions.
 * Please <a href="https://github.com/maniacbug/RF24/issues/new">open an issue</a> if you find any problems using it with any version of Arduino.
 *
 * NOW COMPATIBLE WITH MAPLE - RF24 has been tested with the
 * <a href="http://leaflabs.com/store/#Maple-Native">Maple Native</a>,
 * and should work with any Maple board.  See the pingpair_maple example.
 * Note that only the pingpair_maple example has been tested on Maple, although
 * the others can certainly be adapted.
 *
 * @section Useful Useful References
 *
 * Please refer to:
 *
 * @li <a href="http://maniacbug.github.com/RF24/">Documentation Main Page</a>
 * @li <a href="http://maniacbug.github.com/RF24/classRF24.html">RF24 Class Documentation</a>
 * @li <a href="https://github.com/maniacbug/RF24/">Source Code</a>
 * @li <a href="https://github.com/maniacbug/RF24/archives/master">Downloads Page</a>
 * @li <a href="http://www.nordicsemi.com/files/Product/data_sheet/nRF24L01_Product_Specification_v2_0.pdf">Chip Datasheet</a>
 *
 * This chip uses the SPI bus, plus two chip control pins.  Remember that pin 10 must still remain an output, or
 * the SPI hardware will go into 'slave' mode.
 *
 * @section More More Information
 *
 * @subpage FAQ
 *
 * @section Projects Projects
 *
 * Stuff I have built with RF24
 *
 * <img src="http://farm7.staticflickr.com/6044/6307669179_a8d19298a6_m.jpg" width="240" height="160" alt="RF24 Getting Started - Finished Product">
 *
 * <a style="text-align:center" href="http://maniacbug.wordpress.com/2011/11/02/getting-started-rf24/">Getting Started with nRF24L01+ on Arduino</a>
 *
 * <img src="http://farm8.staticflickr.com/7159/6645514331_38eb2bdeaa_m.jpg" width="240" height="160" alt="Nordic FOB and nRF24L01+">
 *
 * <a style="text-align:center" href="http://maniacbug.wordpress.com/2012/01/08/nordic-fob/">Using the Sparkfun Nordic FOB</a>
 *
 * <img src="http://farm7.staticflickr.com/6097/6224308836_b9b3b421a3_m.jpg" width="240" height="160" alt="RF Duinode V3 (2V4)">
 *
 * <a href="http://maniacbug.wordpress.com/2011/10/19/sensor-node/">Low-Power Wireless Sensor Node</a>
 *
 * <img src="http://farm8.staticflickr.com/7012/6489477865_b56edb629b_m.jpg" width="240" height="161" alt="nRF24L01+ connected to Leaf Labs Maple Native">
 *
 * <a href="http://maniacbug.wordpress.com/2011/12/14/nrf24l01-running-on-maple-3/">nRF24L01+ Running on Maple</a>
 */

#endif // __RF24_H__
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