ststm32_SPI_virtual.patch

diff --git a/libraries/SPI/src/SPI.h b/libraries/SPI/src/SPI.h
index 4cbfe19736..a79ccb311f 100644
--- a/libraries/SPI/src/SPI.h
+++ b/libraries/SPI/src/SPI.h
@@ -151,21 +151,21 @@ class SPIClass {
       _spi.pin_ssel = (ssel);
     };
 
-    void begin(uint8_t _pin = CS_PIN_CONTROLLED_BY_USER);
-    void end(void);
+    virtual void begin(uint8_t _pin = CS_PIN_CONTROLLED_BY_USER);
+    virtual void end(void);
 
     /* This function should be used to configure the SPI instance in case you
      * don't use default parameters.
      * You can attach another CS pin to the SPI instance and each CS pin can be
      * attach with specific SPI settings.
      */
-    void beginTransaction(uint8_t pin, SPISettings settings);
+    virtual void beginTransaction(uint8_t pin, SPISettings settings);
     void beginTransaction(SPISettings settings)
     {
       beginTransaction(CS_PIN_CONTROLLED_BY_USER, settings);
     }
 
-    void endTransaction(uint8_t pin);
+    virtual void endTransaction(uint8_t pin);
     void endTransaction(void)
     {
       endTransaction(CS_PIN_CONTROLLED_BY_USER);
@@ -175,10 +175,10 @@ class SPIClass {
      * instance with begin() or beginTransaction().
      * You can specify the CS pin to use.
      */
-    byte transfer(uint8_t pin, uint8_t _data, SPITransferMode _mode = SPI_LAST);
-    uint16_t transfer16(uint8_t pin, uint16_t _data, SPITransferMode _mode = SPI_LAST);
-    void transfer(uint8_t pin, void *_buf, size_t _count, SPITransferMode _mode = SPI_LAST);
-    void transfer(byte _pin, void *_bufout, void *_bufin, size_t _count, SPITransferMode _mode = SPI_LAST);
+    virtual byte transfer(uint8_t pin, uint8_t _data, SPITransferMode _mode = SPI_LAST);
+    virtual uint16_t transfer16(uint8_t pin, uint16_t _data, SPITransferMode _mode = SPI_LAST);
+    virtual void transfer(uint8_t pin, void *_buf, size_t _count, SPITransferMode _mode = SPI_LAST);
+    virtual void transfer(byte _pin, void *_bufout, void *_bufin, size_t _count, SPITransferMode _mode = SPI_LAST);
 
     // Transfer functions when user controls himself the CS pin.
     byte transfer(uint8_t _data, SPITransferMode _mode = SPI_LAST)
@@ -223,11 +223,11 @@ class SPIClass {
     }
 
     // Not implemented functions. Kept for backward compatibility.
-    void usingInterrupt(uint8_t interruptNumber);
-    void attachInterrupt(void);
-    void detachInterrupt(void);
+    virtual void usingInterrupt(uint8_t interruptNumber);
+    virtual void attachInterrupt(void);
+    virtual void detachInterrupt(void);
 
-  private:
+  protected:
     /* Contains various spiSettings for the same spi instance. Each spi spiSettings
     is associated to a CS pin. */
     SPISettings   spiSettings[NB_SPI_SETTINGS];
@@ -238,6 +238,7 @@ class SPIClass {
     // spi instance
     spi_t         _spi;
 
+  private:
 
     typedef enum {
       GET_IDX = 0,
diff --git a/libraries/SPI/src/SPI.cpp b/libraries/SPI/src/SPI.cpp
index cab53b9..bb1b7e5 100644
--- a/libraries/SPI/src/SPI.cpp
+++ b/libraries/SPI/src/SPI.cpp
@@ -11,8 +11,10 @@
 
 #include "SPI.h"
 
-SPIClass SPI;
+#ifndef DERIVED_EXTERN_SPI
+SPIClass SPI;
+#endif-SPIClass SPI;

 /**
   * @brief  Default constructor. Uses pin configuration of variant.h.
   */