beginTransactionWithAssertingCS() and endTransactionWithDeassertingCS()

These two methods are similar to beginTransaction() and endTransaction(),
but, as the name implies, with CS management. They are both public, as
beginTransaction() and endTransaction() are too.

Adafruit_SPIDevice.cpp

@@ -282,6 +282,26 @@ void Adafruit_SPIDevice::endTransaction(void) {
   }
 }
 
+/*!
+ *    @brief  Write a buffer or two to the SPI device, with transaction
+ * management.
+ *    @brief  Manually begin a transaction (calls beginTransaction if hardware
+ *            SPI) with asserting the CS pin
+ */
+void Adafruit_SPIDevice::beginTransactionWithAssertingCS() {
+  beginTransaction();
+  setChipSelect(LOW);
+}
+
+/*!
+ *    @brief  Manually end a transaction (calls endTransaction if hardware SPI)
+ *            with deasserting the CS pin
+ */
+void Adafruit_SPIDevice::endTransactionWithDeassertingCS() {
+  setChipSelect(HIGH);
+  endTransaction();
+}
+
 /*!
  *    @brief  Write a buffer or two to the SPI device, with transaction
  * management.

Adafruit_SPIDevice.h

@@ -88,6 +88,8 @@ public:
   void transfer(uint8_t *buffer, size_t len);
   void beginTransaction(void);
   void endTransaction(void);
+  void beginTransactionWithAssertingCS();
+  void endTransactionWithDeassertingCS();
 
 private:
   SPIClass *_spi;