#24 Add softSPI supp, fix SPI_UART

- Added softSPI support for https://github.com/greiman/DigitalIO library
- Updated SPI_UART code to allow use at the same time as the SPI library

RF24.cpp

@@ -19,7 +19,7 @@ void RF24::csn(bool mode)
   // divider of 4 is the minimum we want.
   // CLK:BUS 8Mhz:2Mhz, 16Mhz:4Mhz, or 20Mhz:5Mhz
 #ifdef ARDUINO
-	#if  ( !defined(RF24_TINY) && !defined (__arm__)  ) || defined (CORE_TEENSY)
+	#if  ( !defined(RF24_TINY) && !defined (__arm__)  && !defined (SOFTSPI)) || defined (CORE_TEENSY)
  			SPI.setBitOrder(MSBFIRST);
   			SPI.setDataMode(SPI_MODE0);
 			SPI.setClockDivider(SPI_CLOCK_DIV2);
@@ -38,7 +38,7 @@ void RF24::csn(bool mode)
 		} 
 		else {
 			PORTB &= ~(1<<PINB2);	// SCK->CSN LOW
-			delayMicroseconds(20);  // allow csn to settle
+			delayMicroseconds(11);  // allow csn to settle
 		}
 	}		
 #else if !defined  (__arm__) || defined (CORE_TEENSY)

RF24.h

@@ -16,7 +16,9 @@
 #define __RF24_H__
 
 #include <RF24_config.h>
-
+#if defined SOFTSPI
+#include <DigitalIO.h>
+#endif
 /**
  * Power Amplifier level.
  *
@@ -45,6 +47,12 @@ typedef enum { RF24_CRC_DISABLED = 0, RF24_CRC_8, RF24_CRC_16 } rf24_crclength_e
 class RF24
 {
 private:
+#ifdef SOFTSPI
+  SoftSPI<SOFT_SPI_MISO_PIN, SOFT_SPI_MOSI_PIN, SOFT_SPI_SCK_PIN, SPI_MODE> spi;
+#endif
+#ifdef SPI_UART
+  SPIUARTClass spi;
+#endif
   uint8_t ce_pin; /**< "Chip Enable" pin, activates the RX or TX role */
   uint8_t csn_pin; /**< SPI Chip select */  
   bool p_variant; /* False for RF24L01 and true for RF24L01P */

RF24_config.h

@@ -25,6 +25,7 @@
   //#define SERIAL_DEBUG  
   //#define MINIMAL
   #define SPI_UART
+  //#define SOFTSPI
   /**********************/
 
   // Define _BV for non-Arduino platforms and for Arduino DUE
@@ -34,6 +35,16 @@
 	#else
       #if defined SPI_UART
 		#include <SPI_UART.h>
+		#define SPI spi
+	  #elif defined SOFTSPI
+	  // change these pins to your liking
+      //
+      const uint8_t SOFT_SPI_MISO_PIN = 16; 
+      const uint8_t SOFT_SPI_MOSI_PIN = 15;
+      const uint8_t SOFT_SPI_SCK_PIN = 14;
+      const uint8_t SPI_MODE = 0;
+      #define SPI spi
+
 	  #else
 		#include <SPI.h>
 	  #endif