Added SPI pins for TMC's

Author: petrzmax

Marlin/src/pins/stm32/pins_MKS_ROBIN_NANO.h

@@ -113,6 +113,52 @@
 
 #define LED_PIN            PB2
 
+#if HAS_TMC220x
+  /**
+   * TMC2208/TMC2209 stepper drivers
+   *
+   * Hardware serial communication ports.
+   * If undefined software serial is used according to the pins below
+   */
+  //#define X_HARDWARE_SERIAL  Serial1
+  //#define Y_HARDWARE_SERIAL  Serial1
+  //#define Z_HARDWARE_SERIAL  Serial1
+  //#define E0_HARDWARE_SERIAL Serial1
+  //#define E1_HARDWARE_SERIAL Serial1
+
+  //
+  // Software serial
+  //
+
+  #ifndef X_SERIAL_TX_PIN
+    #define X_SERIAL_TX_PIN  PB2 //LED_PIN
+  #endif
+  #ifndef X_SERIAL_RX_PIN
+    #define X_SERIAL_RX_PIN  PE6 //MAX6675_SS_PIN
+  #endif
+
+  #ifndef Y_SERIAL_TX_PIN
+    #define Y_SERIAL_TX_PIN  PB2 //LED_PIN
+  #endif
+  #ifndef Y_SERIAL_RX_PIN
+    #define Y_SERIAL_RX_PIN  PE6 //MAX6675_SS_PIN
+  #endif
+
+  #ifndef Z_SERIAL_TX_PIN
+    #define Z_SERIAL_TX_PIN  PB2 //LED_PIN
+  #endif
+  #ifndef Z_SERIAL_RX_PIN
+    #define Z_SERIAL_RX_PIN  PE6 //MAX6675_SS_PIN
+  #endif
+
+  #ifndef E0_SERIAL_TX_PIN
+    #define E0_SERIAL_TX_PIN PB2 //LED_PIN
+  #endif
+  #ifndef E0_SERIAL_RX_PIN
+    #define E0_SERIAL_RX_PIN PE6 //MAX6675_SS_PIN
+  #endif
+#endif
+
 //
 // SD Card
 //