Further cleanup of inline delays

Marlin/src/core/macros.h

@@ -50,45 +50,58 @@
   #define CYCLES_PER_MICROSECOND (F_CPU / 1000000L) // 16 or 20 on AVR
 #endif
 
-// Highly granular delays for step pulses, etc.
-#define DELAY_0_NOP NOOP
-#define DELAY_1_NOP __asm__("nop\n\t")
-#define DELAY_2_NOP do{ DELAY_1_NOP; DELAY_1_NOP; }while(0)
-#define DELAY_3_NOP do{ DELAY_1_NOP; DELAY_2_NOP; }while(0)
-#define DELAY_4_NOP do{ DELAY_1_NOP; DELAY_3_NOP; }while(0)
-#define DELAY_5_NOP do{ DELAY_1_NOP; DELAY_4_NOP; }while(0)
-
+// Processor-level delays for hardware interfaces
+#ifndef _NOP
+  #define _NOP() do { __asm__ volatile ("nop"); } while (0)
+#endif
 #define DELAY_NOPS(X) \
   switch (X) { \
-    case 20: DELAY_1_NOP; case 19: DELAY_1_NOP; \
-    case 18: DELAY_1_NOP; case 17: DELAY_1_NOP; \
-    case 16: DELAY_1_NOP; case 15: DELAY_1_NOP; \
-    case 14: DELAY_1_NOP; case 13: DELAY_1_NOP; \
-    case 12: DELAY_1_NOP; case 11: DELAY_1_NOP; \
-    case 10: DELAY_1_NOP; case 9:  DELAY_1_NOP; \
-    case 8:  DELAY_1_NOP; case 7:  DELAY_1_NOP; \
-    case 6:  DELAY_1_NOP; case 5:  DELAY_1_NOP; \
-    case 4:  DELAY_1_NOP; case 3:  DELAY_1_NOP; \
-    case 2:  DELAY_1_NOP; case 1:  DELAY_1_NOP; \
+    case 20: _NOP(); case 19: _NOP(); case 18: _NOP(); case 17: _NOP(); \
+    case 16: _NOP(); case 15: _NOP(); case 14: _NOP(); case 13: _NOP(); \
+    case 12: _NOP(); case 11: _NOP(); case 10: _NOP(); case  9: _NOP(); \
+    case  8: _NOP(); case  7: _NOP(); case  6: _NOP(); case  5: _NOP(); \
+    case  4: _NOP(); case  3: _NOP(); case  2: _NOP(); case  1: _NOP(); \
   }
+#define DELAY_0_NOP   NOOP
+#define DELAY_1_NOP   DELAY_NOPS( 1)
+#define DELAY_2_NOP   DELAY_NOPS( 2)
+#define DELAY_3_NOP   DELAY_NOPS( 3)
+#define DELAY_4_NOP   DELAY_NOPS( 4)
+#define DELAY_5_NOP   DELAY_NOPS( 5)
+#define DELAY_10_NOP  DELAY_NOPS(10)
+#define DELAY_20_NOP  DELAY_NOPS(20)
 
-#define DELAY_10_NOP do{ DELAY_5_NOP;  DELAY_5_NOP;  }while(0)
-#define DELAY_20_NOP do{ DELAY_10_NOP; DELAY_10_NOP; }while(0)
-
-#if CYCLES_PER_MICROSECOND == 16
-  #define DELAY_1US do { DELAY_10_NOP; DELAY_5_NOP; DELAY_1_NOP; }while(0)
+#if CYCLES_PER_MICROSECOND <= 200
+  #define DELAY_100NS DELAY_NOPS((CYCLES_PER_MICROSECOND + 9) / 10)
 #else
-  #define DELAY_1US DELAY_20_NOP
+  #define DELAY_100NS DELAY_20_NOP
 #endif
-#define DELAY_2US  do{ DELAY_1US; DELAY_1US; }while(0)
-#define DELAY_3US  do{ DELAY_1US; DELAY_2US; }while(0)
-#define DELAY_4US  do{ DELAY_1US; DELAY_3US; }while(0)
-#define DELAY_5US  do{ DELAY_1US; DELAY_4US; }while(0)
-#define DELAY_6US  do{ DELAY_1US; DELAY_5US; }while(0)
-#define DELAY_7US  do{ DELAY_1US; DELAY_6US; }while(0)
-#define DELAY_8US  do{ DELAY_1US; DELAY_7US; }while(0)
-#define DELAY_9US  do{ DELAY_1US; DELAY_8US; }while(0)
-#define DELAY_10US do{ DELAY_1US; DELAY_9US; }while(0)
+
+// Microsecond delays for hardware interfaces
+#if CYCLES_PER_MICROSECOND <= 20
+  #define DELAY_1US DELAY_NOPS(CYCLES_PER_MICROSECOND)
+  #define DELAY_US(X) \
+    switch (X) { \
+      case 20: DELAY_1US; case 19: DELAY_1US; case 18: DELAY_1US; case 17: DELAY_1US; \
+      case 16: DELAY_1US; case 15: DELAY_1US; case 14: DELAY_1US; case 13: DELAY_1US; \
+      case 12: DELAY_1US; case 11: DELAY_1US; case 10: DELAY_1US; case  9: DELAY_1US; \
+      case  8: DELAY_1US; case  7: DELAY_1US; case  6: DELAY_1US; case  5: DELAY_1US; \
+      case  4: DELAY_1US; case  3: DELAY_1US; case  2: DELAY_1US; case  1: DELAY_1US; \
+    }
+#else
+  #define DELAY_US(X) delayMicroseconds(X) // May not be usable in CRITICAL_SECTION
+  #define DELAY_1US DELAY_US(1)
+#endif
+#define DELAY_2US  DELAY_US( 2)
+#define DELAY_3US  DELAY_US( 3)
+#define DELAY_4US  DELAY_US( 4)
+#define DELAY_5US  DELAY_US( 5)
+#define DELAY_6US  DELAY_US( 6)
+#define DELAY_7US  DELAY_US( 7)
+#define DELAY_8US  DELAY_US( 8)
+#define DELAY_9US  DELAY_US( 9)
+#define DELAY_10US DELAY_US(10)
+#define DELAY_20US DELAY_US(20)
 
 // Remove compiler warning on an unused variable
 #define UNUSED(x) (void) (x)

Marlin/src/module/temperature.cpp

@@ -1632,9 +1632,7 @@ void Temperature::disable_all_heaters() {
 
     WRITE(MAX6675_SS, 0); // enable TT_MAX6675
 
-    // ensure 100ns delay - a bit extra is fine
-    asm("nop");//50ns on 20Mhz, 62.5ns on 16Mhz
-    asm("nop");//50ns on 20Mhz, 62.5ns on 16Mhz
+    DELAY_100NS;          // Ensure 100ns delay
 
     // Read a big-endian temperature value
     max6675_temp = 0;