Merge pull request #386 from homeodor/master

Add bool dmaBusy()

Adafruit_SPITFT.cpp

@@ -1171,6 +1171,19 @@ void Adafruit_SPITFT::dmaWait(void) {
 #endif
 }
 
+/*!
+    @brief  Check if DMA transfer is active. Always returts false if DMA
+            is not enabled.
+    @return true if DMA is enabled and transmitting data, false otherwise.
+*/
+bool Adafruit_SPITFT::dmaBusy(void) const {
+#if defined(USE_SPI_DMA) && (defined(__SAMD51__) || defined(ARDUINO_SAMD_ZERO))
+  return dma_busy;
+#else
+  return false;
+#endif
+}
+
 /*!
     @brief  Issue a series of pixels, all the same color. Not self-
             contained; should follow startWrite() and setAddrWindow() calls.

Adafruit_SPITFT.h

@@ -234,6 +234,7 @@ public:
   void dmaWait(void);
   // Used by writePixels() in some situations, but might have rare need in
   // user code, so it's public...
+  bool dmaBusy(void) const; // true if DMA is used and busy, false otherwise
   void swapBytes(uint16_t *src, uint32_t len, uint16_t *dest = NULL);
 
   // These functions are similar to the 'write' functions above, but with