Simplified example to use less calls.

Defaults now to 32-byte payloads, but you can call in with any size under that.  Added example to docs.

.gitignore

@@ -1,2 +1,3 @@
+*.o
 .*.swp
 docs/

Doxyfile

@@ -631,7 +631,7 @@ EXCLUDE_SYMBOLS        =
 # directories that contain example code fragments that are included (see
 # the \include command).
 
-EXAMPLE_PATH           =
+EXAMPLE_PATH           = examples
 
 # If the value of the EXAMPLE_PATH tag contains directories, you can use the
 # EXAMPLE_PATTERNS tag to specify one or more wildcard pattern (like *.cpp
@@ -645,7 +645,7 @@ EXAMPLE_PATTERNS       =
 # commands irrespective of the value of the RECURSIVE tag.
 # Possible values are YES and NO. If left blank NO is used.
 
-EXAMPLE_RECURSIVE      = NO
+EXAMPLE_RECURSIVE      = YES
 
 # The IMAGE_PATH tag can be used to specify one or more files or
 # directories that contain image that are included in the documentation (see
@@ -1548,4 +1548,4 @@ GENERATE_LEGEND        = YES
 # remove the intermediate dot files that are used to generate
 # the various graphs.
 
-DOT_CLEANUP            = YES
+DOT_CLEANUP            = YES

RF24.cpp

@@ -80,17 +80,20 @@ uint8_t RF24::write_register(uint8_t reg, uint8_t value)
 
 /******************************************************************/
 
-uint8_t RF24::write_payload(const void* buf)
+uint8_t RF24::write_payload(const void* buf, uint8_t len)
 {
   uint8_t status;
 
   const uint8_t* current = (const uint8_t*)buf;
 
   csn(LOW);
   status = SPI.transfer( W_TX_PAYLOAD );
-  uint8_t len = payload_size;
-  while ( len-- )
+  uint8_t data_len = min(len,payload_size);
+  uint8_t blank_len = payload_size - data_len;
+  while ( data_len-- )
     SPI.transfer(*current++);
+  while ( blank_len-- )
+    SPI.transfer(0);
 
   csn(HIGH);
 
@@ -99,16 +102,19 @@ uint8_t RF24::write_payload(const void* buf)
 
 /******************************************************************/
 
-uint8_t RF24::read_payload(void* buf) 
+uint8_t RF24::read_payload(void* buf, uint8_t len) 
 {
   uint8_t status;
   uint8_t* current = (uint8_t*)buf;
 
   csn(LOW);
   status = SPI.transfer( R_RX_PAYLOAD );
-  uint8_t len = payload_size;
-  while ( len-- )
+  uint8_t data_len = min(len,payload_size);
+  uint8_t blank_len = payload_size - data_len;
+  while ( data_len-- )
     *current++ = SPI.transfer(0xff);
+  while ( blank_len-- )
+    SPI.transfer(0xff);
   csn(HIGH);
 
   return status;
@@ -181,7 +187,7 @@ void RF24::print_observe_tx(uint8_t value)
 /******************************************************************/
 
 RF24::RF24(int _cepin, int _cspin): 
-  ce_pin(_cepin), csn_pin(_cspin)
+  ce_pin(_cepin), csn_pin(_cspin), payload_size(32)
 {
 }
 
@@ -197,7 +203,6 @@ void RF24::setChannel(int channel)
 void RF24::setPayloadSize(uint8_t size)
 {
   payload_size = min(size,32);
-  write_register(RX_PW_P0,min(size,32));
 }
 
 /******************************************************************/
@@ -300,15 +305,15 @@ void RF24::stopListening(void)
 
 /******************************************************************/
 
-boolean RF24::write( const void* buf )
+boolean RF24::write( const void* buf, uint8_t len )
 {
   boolean result = false;
 
   // Transmitter power-up
   write_register(CONFIG, _BV(EN_CRC) | _BV(PWR_UP));
 
   // Send the payload
-  write_payload( buf );
+  write_payload( buf, len );
 
   // Allons!
   ce(HIGH);
@@ -366,13 +371,13 @@ boolean RF24::available(void)
 
 /******************************************************************/
 
-boolean RF24::read( void* buf ) 
+boolean RF24::read( void* buf, uint8_t len ) 
 {
   // was this the last of the data available?
   boolean result = false;
 
   // Fetch the payload
-  read_payload( buf );
+  read_payload( buf, len );
 
   uint8_t fifo_status;
   read_register(FIFO_STATUS,&fifo_status,1);
@@ -391,6 +396,7 @@ void RF24::openWritingPipe(uint64_t value)
 
   write_register(RX_ADDR_P0, reinterpret_cast<uint8_t*>(&value), 5);
   write_register(TX_ADDR, reinterpret_cast<uint8_t*>(&value), 5);  
+  write_register(RX_PW_P0,min(payload_size,32));
 }
 
 /******************************************************************/

RF24.h

@@ -14,16 +14,20 @@
 /**
  * Driver for nRF24L01 2.4GHz Wireless Transceiver
  *
- * See <a href="http://www.nordicsemi.com/files/Product/data_sheet/nRF24L01_Product_Specification_v2_0.pdf">Datasheet</a>
+ * Please refer to:
+ *
+ * @li <a href="http://maniacbug.github.com/RF24/classRF24.html">Detailed Documentation</a>
+ * @li <a href="https://github.com/maniacbug/RF24/">Source Code</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.
  *
  * Design Goals: This library is designed to be...
- *   * Maximally compliant with the intended operation of the chip
- *   * Easy for beginners to use
- *   * Consumed with a public interface that's similiar to other Arduino standard libraries
- *   * Built against the standard SPI library. 
+ * @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
+ * @li Built against the standard SPI library. 
  */
 
 class RF24
@@ -91,19 +95,21 @@ class RF24
    * 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 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 read_payload(void* buf, uint8_t len) ;
 
   /**
    * Empty the receive buffer
@@ -222,12 +228,15 @@ class RF24
    * the receiver or the timeout/retransmit maxima are reached.  In
    * the current configuration, the max delay here is 60ms.
    *
-   * The size of data written is the fixed payload size, see getPayloadSize()
+   * 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
    */
-  boolean write( const void* buf );
+  boolean write( const void* buf, uint8_t len );
 
   /**
    * Test whether there are bytes available to be read
@@ -249,9 +258,10 @@ class RF24
    * 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
    */
-  boolean read( void* buf ) ;
+  boolean read( void* buf, uint8_t len ) ;
 
   /**
    * Open a pipe for writing
@@ -296,6 +306,21 @@ class RF24
    */
   void openReadingPipe(uint8_t number, uint64_t address);
 
-}; 
+};
+
+/**
+ * @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.
+ */
+
+/**
+ * @mainpage Driver Library for nRF24L01
+ *
+ * See the RF24 class for details on how to drive this chip.
+ */
+
 #endif // __RF24_H__
 

examples/pingpair/.gitignore

@@ -0,0 +1 @@
+output/