Merge pull request #1607 from chris-bo/Development

Update ultralcd_st7920_u8glib_rrd.h

Marlin/ultralcd_st7920_u8glib_rrd.h

@@ -27,9 +27,15 @@ static void ST7920_SWSPI_SND_8BIT(uint8_t val)
   for( i=0; i<8; i++ )
   {
     WRITE(ST7920_CLK_PIN,0);
+    #if F_CPU == 20000000
+      __asm__("nop\n\t"); 
+    #endif
     WRITE(ST7920_DAT_PIN,val&0x80); 
     val<<=1;
     WRITE(ST7920_CLK_PIN,1);
+    #if F_CPU == 20000000
+      __asm__("nop\n\t""nop\n\t"); 
+    #endif
   }
 }