Added display_Clear.

src/board.c

@@ -257,6 +257,8 @@ void display_Init(void) {
 
   HT1632C_CS_OFF;
   GPIO_SPI_HW();
+
+  display_Clear();
 }
 
 /**
@@ -475,6 +477,17 @@ void display_WriteBuffer(void) {
   /* End of transaction in DMA1_Channel2_3_IRQHandler() */
 }
 
+/**
+ * @brief Clear display by zeroing display buffer.
+ */
+void display_Clear(void) {
+  int i;
+  for (i=0; i<DISPLAY_COLUMNS; i++) {
+    display_Buffer[i] = 0x0;
+  }
+  display_WriteBuffer();
+}
+
 /**
   * @brief This function handles EXTI line 4 to 15 interrupts.
   */