Reduce error rate in call response scenarios

- Added delay to first call to available()
a: Only delays IF called after startListening AND called less than a
certain time after the last time it was called
- Corrected mistake on last commit where flush_rx was added back
inadvertently

RF24.cpp

@@ -834,9 +834,12 @@ bool RF24::available(void)
 
 bool RF24::available(uint8_t* pipe_num)
 {
-
-  //Check the FIFO buffer to see if data is waitng to be read
-
+    //Check the FIFO buffer to see if data is waiting to be read
+	if(listeningStarted){
+		while(micros() - lastAvailableCheck < 800 && listeningStarted){};
+		lastAvailableCheck = micros();
+		listeningStarted = 0;
+	}
   if (!( read_register(FIFO_STATUS) & _BV(RX_EMPTY) )){
 
     // If the caller wants the pipe number, include that

RF24.h

@@ -52,8 +52,9 @@ class RF24
   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 lastAvailableCheck = 0; /**< Limits the amount of time betwen reading data, only when switching between modes */
+  boolean listeningStarted = 1; /**< Var for delaying available() after start listening */
 
-
 public:
 
   /**

RPi/RF24/RF24.cpp

@@ -514,7 +514,7 @@ void RF24::startListening(void)
     closeReadingPipe(0);
   }
   // Flush buffers
-  flush_rx();
+  //flush_rx();
   if(read_register(FEATURE) & _BV(EN_ACK_PAY)){
 	flush_tx();
   }
@@ -523,7 +523,8 @@ void RF24::startListening(void)
   bcm2835_gpio_write(ce_pin, HIGH);
 
   // wait for the radio to come up (130us actually only needed)
-  delayMicroseconds(130);
+  //delayMicroseconds(130);
+  listeningStarted = 1;
 }
 
 /****************************************************************************/
@@ -541,7 +542,7 @@ void RF24::stopListening(void)
   if(read_register(FEATURE) & _BV(EN_ACK_PAY)){
 	flush_tx();
   }
-  flush_rx();
+  //flush_rx();
 
   write_register(CONFIG, ( read_register(CONFIG) ) & ~_BV(PRIM_RX) );  
   write_register(EN_RXADDR,read_register(EN_RXADDR) | _BV(pgm_read_byte(&child_pipe_enable[0])));
@@ -812,11 +813,16 @@ bool RF24::available(void)
 /****************************************************************************/
 
 bool RF24::available(uint8_t* pipe_num)
-{
+{	
+
+	if(listeningStarted){
+		if(millis() - lastAvailableCheck < 2 && listeningStarted){delayMicroseconds(400);}
+		lastAvailableCheck = millis();
+		listeningStarted = 0;
+	}
     //Check the FIFO buffer to see if data is waitng to be read
   if (!( read_register(FIFO_STATUS) & _BV(RX_EMPTY) )){
 
-
     // If the caller wants the pipe number, include that
     if ( pipe_num ){
 	  uint8_t status = get_status();

RPi/RF24/RF24.h

@@ -91,6 +91,9 @@ class RF24
   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 listeningStarted; /**< Var for delaying available() after start listening */
+  uint32_t lastAvailableCheck;  /**< Var for preventing available() from being called too often */
+
 protected:
   /**
    * @name Low-level internal interface.