File content as of revision 3:13e43d3101a5:

/*
 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 "mbed.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 */
    //uint16_t spi_speed; /**< SPI Bus Speed */

    uint8_t spi_rxbuff[32+1] ; //SPI receive buffer (payload max 32 bytes)
    uint8_t spi_txbuff[32+1] ; //SPI transmit buffer (payload max 32 bytes + 1 byte for the command)

    bool p_variant; /* False for RF24L01 and true for RF24L01P */
    uint8_t payload_size; /**< Fixed size of payloads */
    bool dynamic_payloads_enabled; /**< Whether dynamic payloads are enabled. */
    uint8_t pipe0_reading_address[5]; /**< Last address set on pipe 0 for reading. */
    uint8_t addr_width; /**< The address width to use - 3,4 or 5 bytes. */
    uint32_t txRxDelay; /**< Var for adjusting delays depending on datarate */

    SPI spi;

    Timer mainTimer;


protected:
    /**
     * SPI transactions
     *
     * Common code for SPI transactions including CSN toggle
     *
     */
    void beginTransaction(); // inline removed

    void endTransaction(); // inline removed

public:

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

    /**
     * Arduino 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 _cepin The pin attached to Chip Enable on the RF module
     * @param _cspin The pin attached to Chip Select
     */
    RF24(PinName mosi, PinName miso, PinName sck, PinName _cspin, PinName _cepin);

    virtual ~RF24() {};

    /**
     * Begin operation of the chip
     *
     * Call this in setup(), before calling any other methods.
     * @code radio.begin() @endcode
     */
    bool begin(void);
    void begin_MB(void);

    /**
     * Start listening on the pipes opened for reading.
     *
     * 1. Be sure to call openReadingPipe() first.
     * 2. Do not call write() while in this mode, without first calling stopListening().
     * 3. Call available() to check for incoming traffic, and read() to get it.
     *
     * @code
     * Open reading pipe 1 using address CCCECCCECC
     *
     * byte address[] = { 0xCC,0xCE,0xCC,0xCE,0xCC };
     * radio.openReadingPipe(1,address);
     * radio.startListening();
     * @endcode
     */
    void startListening(void);

    /**
     * Stop listening for incoming messages, and switch to transmit mode.
     *
     * Do this before calling write().
     * @code
     * radio.stopListening();
     * radio.write(&data,sizeof(data));
     * @endcode
     */
    void stopListening(void);

    /**
     * Check whether there are bytes available to be read
     * @code
     * if(radio.available()){
     *   radio.read(&data,sizeof(data));
     * }
     * @endcode
     * @return True if there is a payload available, false if none is
     */
    bool available(void);

    /**
     * Read the available payload
     *
     * 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.
     *
     * @note No longer boolean. Use available to determine if packets are
     * available. Interrupt flags are now cleared during reads instead of
     * when calling available().
     *
     * @param buf Pointer to a buffer where the data should be written
     * @param len Maximum number of bytes to read into the buffer
     *
     * @code
     * if(radio.available()){
     *   radio.read(&data,sizeof(data));
     * }
     * @endcode
     * @return No return value. Use available().
     */
    void read( void* buf, uint8_t len );

    /**
     * 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 60-70ms.
     *
     * 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.
     *
     * TX/RX/RT interrupt flags will be cleared every time write is called
     *
     * @param buf Pointer to the data to be sent
     * @param len Number of bytes to be sent
     *
     * @code
     * radio.stopListening();
     * radio.write(&data,sizeof(data));
     * @endcode
     * @return True if the payload was delivered successfully false if not
     */
    bool write( const void* buf, uint8_t len );

    /**
     * New: Open a pipe for writing via byte array. Old addressing format retained
     * for compatibility.
     *
     * Only one writing pipe can be open at once, but you can change the address
     * you'll write to. Call stopListening() first.
     *
     * Addresses are assigned via a byte array, default is 5 byte address length
    s   *
     * @code
     *   uint8_t addresses[][6] = {"1Node","2Node"};
     *   radio.openWritingPipe(addresses[0]);
     * @endcode
     * @code
     *  uint8_t address[] = { 0xCC,0xCE,0xCC,0xCE,0xCC };
     *  radio.openWritingPipe(address);
     *  address[0] = 0x33;
     *  radio.openReadingPipe(1,address);
     * @endcode
     * @see setAddressWidth
     *
     * @param address The address of the pipe to open. Coordinate these pipe
     * addresses amongst nodes on the network.
     */

    void openWritingPipe(const uint8_t *address);

    /**
     * Open a pipe for reading
     *
     * Up to 6 pipes can be open for reading at once.  Open all the required
     * reading pipes, and then call startListening().
     *
     * @see openWritingPipe
     * @see setAddressWidth
     *
     * @note Pipes 0 and 1 will store a full 5-byte address. Pipes 2-5 will technically
     * only store a single byte, borrowing up to 4 additional bytes from pipe #1 per the
     * assigned address width.
     * @warning Pipes 1-5 should share the same address, except the first byte.
     * Only the first byte in the array should be unique, e.g.
     * @code
     *   uint8_t addresses[][6] = {"1Node","2Node"};
     *   openReadingPipe(1,addresses[0]);
     *   openReadingPipe(2,addresses[1]);
     * @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().
     *
     * @param number Which pipe# to open, 0-5.
     * @param address The 24, 32 or 40 bit address of the pipe to open.
     */

    void openReadingPipe(uint8_t number, const uint8_t *address);

    /**@}*/
    /**
     * @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
     * The printf.h file is included with the library for Arduino.
     * @code
     * #include <printf.h>
     * setup(){
     *  Serial.begin(115200);
     *  printf_begin();
     *  ...
     * }
     * @endcode
     */
    void printDetails(void);

    /**
     * Test whether there are bytes available to be read in the
     * FIFO buffers.
     *
     * @param[out] pipe_num Which pipe has the payload available
     *
     * @code
     * uint8_t pipeNum;
     * if(radio.available(&pipeNum)){
     *   radio.read(&data,sizeof(data));
     *   Serial.print("Got data on pipe");
     *   Serial.println(pipeNum);
     * }
     * @endcode
     * @return True if there is a payload available, false if none is
     */
    bool available(uint8_t* pipe_num);

    /**
     * Check if the radio needs to be read. Can be used to prevent data loss
     * @return True if all three 32-byte radio buffers are full
     */
    bool rxFifoFull();

    /**
     * Enter low-power mode
     *
     * To return to normal power mode, call powerUp().
     *
     * @note After calling startListening(), a basic radio will consume about 13.5mA
     * at max PA level.
     * During active transmission, the radio will consume about 11.5mA, but this will
     * be reduced to 26uA (.026mA) between sending.
     * In full powerDown mode, the radio will consume approximately 900nA (.0009mA)
     *
     * @code
     * radio.powerDown();
     * avr_enter_sleep_mode(); // Custom function to sleep the device
     * radio.powerUp();
     * @endcode
     */
    void powerDown(void);

    /**
     * Leave low-power mode - required for normal radio operation after calling powerDown()
     *
     * To return to low power mode, call powerDown().
     * @note This will take up to 5ms for maximum compatibility
     */
    void powerUp(void) ;

    /**
    * Write for single NOACK writes. Optionally disables acknowledgements/autoretries for a single write.
    *
    * @note enableDynamicAck() must be called to enable this feature
    *
    * Can be used with enableAckPayload() to request a response
    * @see enableDynamicAck()
    * @see setAutoAck()
    * @see write()
    *
    * @param buf Pointer to the data to be sent
    * @param len Number of bytes to be sent
    * @param multicast Request ACK (0), NOACK (1)
    */
    bool write( const void* buf, uint8_t len, const bool multicast );

    /**
     * This will not block until the 3 FIFO buffers are filled with data.
     * Once the FIFOs are full, writeFast will simply wait for success or
     * timeout, and return 1 or 0 respectively. From a user perspective, just
     * keep trying to send the same data. The library will keep auto retrying
     * the current payload using the built in functionality.
     * @warning It is important to never keep the nRF24L01 in TX mode and FIFO full for more than 4ms at a time. If the auto
     * retransmit is enabled, the nRF24L01 is never in TX mode long enough to disobey this rule. Allow the FIFO
     * to clear by issuing txStandBy() or ensure appropriate time between transmissions.
     *
     * @code
     * Example (Partial blocking):
     *
     *            radio.writeFast(&buf,32);  // Writes 1 payload to the buffers
     *            txStandBy();               // Returns 0 if failed. 1 if success. Blocks only until MAX_RT timeout or success. Data flushed on fail.
     *
     *            radio.writeFast(&buf,32);  // Writes 1 payload to the buffers
     *            txStandBy(1000);           // Using extended timeouts, returns 1 if success. Retries failed payloads for 1 seconds before returning 0.
     * @endcode
     *
     * @see txStandBy()
     * @see write()
     * @see writeBlocking()
     *
     * @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 writeFast( const void* buf, uint8_t len );

    /**
    * WriteFast for single NOACK writes. Disables acknowledgements/autoretries for a single write.
    *
    * @note enableDynamicAck() must be called to enable this feature
    * @see enableDynamicAck()
    * @see setAutoAck()
    *
    * @param buf Pointer to the data to be sent
    * @param len Number of bytes to be sent
    * @param multicast Request ACK (0) or NOACK (1)
    */
    bool writeFast( const void* buf, uint8_t len, const bool multicast );

    /**
     * This function extends the auto-retry mechanism to any specified duration.
     * It will not block until the 3 FIFO buffers are filled with data.
     * If so the library will auto retry until a new payload is written
     * or the user specified timeout period is reached.
     * @warning It is important to never keep the nRF24L01 in TX mode and FIFO full for more than 4ms at a time. If the auto
     * retransmit is enabled, the nRF24L01 is never in TX mode long enough to disobey this rule. Allow the FIFO
     * to clear by issuing txStandBy() or ensure appropriate time between transmissions.
     *
     * @code
     * Example (Full blocking):
     *
     *            radio.writeBlocking(&buf,32,1000); //Wait up to 1 second to write 1 payload to the buffers
     *            txStandBy(1000);                   //Wait up to 1 second for the payload to send. Return 1 if ok, 0 if failed.
     *                                               //Blocks only until user timeout or success. Data flushed on fail.
     * @endcode
     * @note If used from within an interrupt, the interrupt should be disabled until completion, and sei(); called to enable millis().
     * @see txStandBy()
     * @see write()
     * @see writeFast()
     *
     * @param buf Pointer to the data to be sent
     * @param len Number of bytes to be sent
     * @param timeout User defined timeout in milliseconds.
     * @return True if the payload was loaded into the buffer successfully false if not
     */
    bool writeBlocking( const void* buf, uint8_t len, uint32_t timeout );

    /**
     * This function should be called as soon as transmission is finished to
     * drop the radio back to STANDBY-I mode. If not issued, the radio will
     * remain in STANDBY-II mode which, per the data sheet, is not a recommended
     * operating mode.
     *
     * @note When transmitting data in rapid succession, it is still recommended by
     * the manufacturer to drop the radio out of TX or STANDBY-II mode if there is
     * time enough between sends for the FIFOs to empty. This is not required if auto-ack
     * is enabled.
     *
     * Relies on built-in auto retry functionality.
     *
     * @code
     * Example (Partial blocking):
     *
     *            radio.writeFast(&buf,32);
     *            radio.writeFast(&buf,32);
     *            radio.writeFast(&buf,32);  //Fills the FIFO buffers up
     *            bool ok = txStandBy();     //Returns 0 if failed. 1 if success.
     *                                       //Blocks only until MAX_RT timeout or success. Data flushed on fail.
     * @endcode
     * @see txStandBy(unsigned long timeout)
     * @return True if transmission is successful
     *
     */
    bool txStandBy();

    /**
     * This function allows extended blocking and auto-retries per a user defined timeout
     * @code
     *    Fully Blocking Example:
     *
     *            radio.writeFast(&buf,32);
     *            radio.writeFast(&buf,32);
     *            radio.writeFast(&buf,32);   //Fills the FIFO buffers up
     *            bool ok = txStandBy(1000);  //Returns 0 if failed after 1 second of retries. 1 if success.
     *                                        //Blocks only until user defined timeout or success. Data flushed on fail.
     * @endcode
     * @note If used from within an interrupt, the interrupt should be disabled until completion, and sei(); called to enable millis().
     * @param timeout Number of milliseconds to retry failed payloads
     * @return True if transmission is successful
     *
     */
    bool txStandBy(uint32_t timeout, bool startTx = 0);

    /**
     * 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.
     * @see enableAckPayload()
     * @see enableDynamicPayloads()
     * @warning Only three of these can be pending at any time as there are only 3 FIFO buffers.<br> Dynamic payloads must be enabled.
     * @note Ack payloads are handled automatically by the radio chip when a payload is received. Users should generally
     * write an ack payload as soon as startListening() is called, so one is available when a regular payload is received.
     * @note Ack payloads are dynamic payloads. This only works on pipes 0&1 by default. Call
     * enableDynamicPayloads() to enable on all pipes.
     *
     * @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(). The regular available() can also be used.
     *
     * Call read() to retrieve the ack payload.
     *
     * @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);

    /**
     * Non-blocking write to the open writing pipe used for buffered writes
     *
     * @note Optimization: This function now leaves the CE pin high, so the radio
     * will remain in TX or STANDBY-II Mode until a txStandBy() command is issued. Can be used as an alternative to startWrite()
     * if writing multiple payloads at once.
     * @warning It is important to never keep the nRF24L01 in TX mode with FIFO full for more than 4ms at a time. If the auto
     * retransmit/autoAck is enabled, the nRF24L01 is never in TX mode long enough to disobey this rule. Allow the FIFO
     * to clear by issuing txStandBy() or ensure appropriate time between transmissions.
     *
     * @see write()
     * @see writeFast()
     * @see startWrite()
     * @see writeBlocking()
     *
     * For single noAck writes see:
     * @see enableDynamicAck()
     * @see setAutoAck()
     *
     * @param buf Pointer to the data to be sent
     * @param len Number of bytes to be sent
     * @param multicast Request ACK (0) or NOACK (1)
     * @return True if the payload was delivered successfully false if not
     */
    void startFastWrite( const void* buf, uint8_t len, const bool multicast, bool startTx = 1 );

    /**
     * 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 writeFast()
     * @see startFastWrite()
     * @see whatHappened()
     *
     * For single noAck writes see:
     * @see enableDynamicAck()
     * @see setAutoAck()
     *
     * @param buf Pointer to the data to be sent
     * @param len Number of bytes to be sent
     * @param multicast Request ACK (0) or NOACK (1)
     *
     */
    void startWrite( const void* buf, uint8_t len, const bool multicast );

    /**
     * This function is mainly used internally to take advantage of the auto payload
     * re-use functionality of the chip, but can be beneficial to users as well.
     *
     * The function will instruct the radio to re-use the data in the FIFO buffers,
     * and instructs the radio to re-send once the timeout limit has been reached.
     * Used by writeFast and writeBlocking to initiate retries when a TX failure
     * occurs. Retries are automatically initiated except with the standard write().
     * This way, data is not flushed from the buffer until switching between modes.
     *
     * @note This is to be used AFTER auto-retry fails if wanting to resend
     * using the built-in payload reuse features.
     * After issuing reUseTX(), it will keep reending the same payload forever or until
     * a payload is written to the FIFO, or a flush_tx command is given.
     */
    void reUseTX();

    /**
     * Empty the transmit buffer. This is generally not required in standard operation.
     * May be required in specific cases after stopListening() , if operating at 250KBPS data rate.
     *
     * @return Current value of status register
     */
    uint8_t flush_tx(void);

    /**
     * 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.
     *
     * @code
     * bool goodSignal = radio.testRPD();
     * if(radio.available()){
     *    Serial.println(goodSignal ? "Strong signal > 64dBm" : "Weak signal < 64dBm" );
     *    radio.read(0,0);
     * }
     * @endcode
     * @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;
    }

    /**
    * Close a pipe after it has been previously opened.
    * Can be safely called without having previously opened a pipe.
    * @param pipe Which pipe # to close, 0-5.
    */
    void closeReadingPipe( uint8_t pipe ) ;

    /**
    * Enable error detection by un-commenting #define FAILURE_HANDLING in RF24_config.h
    * If a failure has been detected, it usually indicates a hardware issue. By default the library
    * will cease operation when a failure is detected.
    * This should allow advanced users to detect and resolve intermittent hardware issues.
    *
    * In most cases, the radio must be re-enabled via radio.begin(); and the appropriate settings
    * applied after a failure occurs, if wanting to re-enable the device immediately.
    *
    * Usage: (Failure handling must be enabled per above)
    *  @code
    *  if(radio.failureDetected){
    *    radio.begin();                       // Attempt to re-configure the radio with defaults
    *    radio.failureDetected = 0;           // Reset the detection value
    *    radio.openWritingPipe(addresses[1]); // Re-configure pipe addresses
    *    radio.openReadingPipe(1,addresses[0]);
    *    report_failure();                    // Blink leds, send a message, etc. to indicate failure
    *  }
    * @endcode
    */
    //#if defined (FAILURE_HANDLING)
    bool failureDetected;
    //#endif

    /**@}*/

    /**@}*/
    /**
     * @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 address width from 3 to 5 bytes (24, 32 or 40 bit)
    *
    * @param a_width The address width to use: 3,4 or 5
    */

    void setAddressWidth(uint8_t a_width);

    /**
     * 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, 0-125
     */
    void setChannel(uint8_t channel);

    /**
    * Get RF communication channel
    *
    * @return The currently configured RF Channel
    */
    uint8_t getChannel(void);

    /**
     * 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
     *
     * @note Corrupt packets are now detected and flushed per the
     * manufacturer.
     * @code
     * if(radio.available()){
     *   if(radio.getDynamicPayloadSize() < 1){
     *     // Corrupt payload has been flushed
     *     return;
     *   }
     *   radio.read(&data,sizeof(data));
     * }
     * @endcode
     *
     * @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.
     *
     * @note Ack payloads are dynamic payloads. This only works on pipes 0&1 by default. Call
     * enableDynamicPayloads() to enable on all pipes.
     */
    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.
     *
     */
    void enableDynamicPayloads(void);

    /**
     * Enable dynamic ACKs (single write multicast or unicast) for chosen messages
     *
     * @note To enable full multicast or per-pipe multicast, use setAutoAck()
     *
     * @warning This MUST be called prior to attempting single write NOACK calls
     * @code
     * radio.enableDynamicAck();
     * radio.write(&data,32,1);  // Sends a payload with no acknowledgement requested
     * radio.write(&data,32,0);  // Sends a payload using auto-retry/autoACK
     * @endcode
     */
    void enableDynamicAck();

    /**
     * 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:
     * RF24_PA_MIN, RF24_PA_LOW, RF24_PA_HIGH and RF24_PA_MAX
     *
     * The power levels correspond to the following output levels respectively:
     * NRF24L01: -18dBm, -12dBm,-6dBM, and 0dBm
     *
     * SI24R1: -6dBm, 0dBm, 3dBM, and 7dBm.
     *
     * @param level Desired PA level.
     */
    void setPALevel ( uint8_t level );

    /**
     * Fetches the current PA level.
     *
     * NRF24L01: -18dBm, -12dBm, -6dBm and 0dBm
     * SI24R1:   -6dBm, 0dBm, 3dBm, 7dBm
     *
     * @return Returns values 0 to 3 representing the PA Level.
     */
    uint8_t 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
     * <br>CRC checking cannot be disabled if auto-ack is enabled
     * @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
     * <br>CRC checking cannot be disabled if auto-ack is enabled
     * @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
     *
     * @warning CRC cannot be disabled if auto-ack/ESB is enabled.
     */
    void disableCRC( void ) ;

    /**
    * The radio will generate interrupt signals when a transmission is complete,
    * a transmission fails, or a payload is received. This allows users to mask
    * those interrupts to prevent them from generating a signal on the interrupt
    * pin. Interrupts are enabled on the radio chip by default.
    *
    * @code
    *     Mask all interrupts except the receive interrupt:
    *
    *     radio.maskIRQ(1,1,0);
    * @endcode
    *
    * @param tx_ok  Mask transmission complete interrupts
    * @param tx_fail  Mask transmit failure interrupts
    * @param rx_ready Mask payload received interrupts
    */
    void maskIRQ(bool tx_ok,bool tx_fail,bool rx_ready);

    /**@}*/
    /**
     * @name Deprecated
     *
     *  Methods provided for backwards compabibility.
     */
    /**@{*/


    /**
     * Open a pipe for reading
     * @note For compatibility with old code only, see new function
     *
     * @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().
     *
     * @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);

    /**
     * Open a pipe for writing
     * @note For compatibility with old code only, see new function
     *
     * Addresses are 40-bit hex values, e.g.:
     *
     * @code
     *   openWritingPipe(0xF0F0F0F0F0);
     * @endcode
     *
     * @param address The 40-bit address of the pipe to open.
     */
    void openWritingPipe(uint64_t address);

private:

    /**
     * @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 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 csn(int mode);

    /**
     * Set chip enable
     *
     * @param mode HIGH to take this unit off the SPI bus, LOW to put it on
     */
    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, const uint8_t writeType);

    /**
     * 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);

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

#if !defined (MINIMAL)
    /**
     * 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);
#endif
    /**
     * 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);

    /**
     * Built in spi transfer function to simplify repeating code repeating code
     */

    uint8_t spiTrans(uint8_t cmd);

#if defined (FAILURE_HANDLING)
    void errNotify(void);
#endif

    /**@}*/

};


#endif // __RF24_H__