diff --git a/Marlin/src/HAL/HAL_AVR/HAL_AVR.h b/Marlin/src/HAL/HAL_AVR/HAL_AVR.h
index 008f80f5f..5a3d2011a 100644
--- a/Marlin/src/HAL/HAL_AVR/HAL_AVR.h
+++ b/Marlin/src/HAL/HAL_AVR/HAL_AVR.h
@@ -112,21 +112,21 @@ extern "C" {
 #define ENABLE_TEMPERATURE_INTERRUPT()  SBI(TIMSK0, OCIE0B)
 #define DISABLE_TEMPERATURE_INTERRUPT() CBI(TIMSK0, OCIE0B)
 
-//void HAL_timer_start (uint8_t timer_num, uint32_t frequency);
-#define HAL_timer_start (timer_num,frequency)
+//void HAL_timer_start(const uint8_t timer_num, const uint32_t frequency);
+#define HAL_timer_start(timer_num,frequency)
 
-//void HAL_timer_set_count (uint8_t timer_num, uint16_t count);
-#define HAL_timer_set_count(timer,count) timer = (count)
+//void HAL_timer_set_count(const uint8_t timer_num, const uint16_t count);
+#define HAL_timer_set_count(timer, count) timer = (count)
 
 #define HAL_timer_get_current_count(timer) timer
 
-//void HAL_timer_isr_prologue (uint8_t timer_num);
+//void HAL_timer_isr_prologue(const uint8_t timer_num);
 #define HAL_timer_isr_prologue(timer_num)
 
 #define HAL_STEP_TIMER_ISR ISR(TIMER1_COMPA_vect)
 #define HAL_TEMP_TIMER_ISR ISR(TIMER0_COMPB_vect)
 
-#define HAL_ENABLE_ISRs() do { cli(); if (thermalManager.in_temp_isr)DISABLE_TEMPERATURE_INTERRUPT(); else ENABLE_TEMPERATURE_INTERRUPT(); ENABLE_STEPPER_DRIVER_INTERRUPT(); } while(0)
+#define HAL_ENABLE_ISRs() do { cli(); if (thermalManager.in_temp_isr) DISABLE_TEMPERATURE_INTERRUPT(); else ENABLE_TEMPERATURE_INTERRUPT(); ENABLE_STEPPER_DRIVER_INTERRUPT(); } while(0)
 
 // ADC
 #ifdef DIDR2
diff --git a/Marlin/src/HAL/HAL_AVR/servo_AVR.cpp b/Marlin/src/HAL/HAL_AVR/servo_AVR.cpp
index 81a1e8a5c..a57b823ba 100644
--- a/Marlin/src/HAL/HAL_AVR/servo_AVR.cpp
+++ b/Marlin/src/HAL/HAL_AVR/servo_AVR.cpp
@@ -96,19 +96,19 @@ static inline void handle_interrupts(timer16_Sequence_t timer, volatile uint16_t
 
   // Interrupt handlers for Arduino
   #if ENABLED(_useTimer1)
-    SIGNAL (TIMER1_COMPA_vect) { handle_interrupts(_timer1, &TCNT1, &OCR1A); }
+    SIGNAL(TIMER1_COMPA_vect) { handle_interrupts(_timer1, &TCNT1, &OCR1A); }
   #endif
 
   #if ENABLED(_useTimer3)
-    SIGNAL (TIMER3_COMPA_vect) { handle_interrupts(_timer3, &TCNT3, &OCR3A); }
+    SIGNAL(TIMER3_COMPA_vect) { handle_interrupts(_timer3, &TCNT3, &OCR3A); }
   #endif
 
   #if ENABLED(_useTimer4)
-    SIGNAL (TIMER4_COMPA_vect) { handle_interrupts(_timer4, &TCNT4, &OCR4A); }
+    SIGNAL(TIMER4_COMPA_vect) { handle_interrupts(_timer4, &TCNT4, &OCR4A); }
   #endif
 
   #if ENABLED(_useTimer5)
-    SIGNAL (TIMER5_COMPA_vect) { handle_interrupts(_timer5, &TCNT5, &OCR5A); }
+    SIGNAL(TIMER5_COMPA_vect) { handle_interrupts(_timer5, &TCNT5, &OCR5A); }
   #endif
 
 #else // WIRING
diff --git a/Marlin/src/HAL/HAL_DUE/HAL_Due.cpp b/Marlin/src/HAL/HAL_DUE/HAL_Due.cpp
index 2612e28c8..81a279b6d 100644
--- a/Marlin/src/HAL/HAL_DUE/HAL_Due.cpp
+++ b/Marlin/src/HAL/HAL_DUE/HAL_Due.cpp
@@ -112,7 +112,7 @@ int freeMemory() {
 // ADC
 // --------------------------------------------------------------------------
 
-void HAL_adc_start_conversion (uint8_t adc_pin) {
+void HAL_adc_start_conversion(uint8_t adc_pin) {
   HAL_adc_result = analogRead(adc_pin);
 }
 
diff --git a/Marlin/src/HAL/HAL_DUE/HAL_timers_Due.cpp b/Marlin/src/HAL/HAL_DUE/HAL_timers_Due.cpp
index 9a502db00..0802624de 100644
--- a/Marlin/src/HAL/HAL_DUE/HAL_timers_Due.cpp
+++ b/Marlin/src/HAL/HAL_DUE/HAL_timers_Due.cpp
@@ -92,18 +92,18 @@ const tTimerConfig TimerConfig [NUM_HARDWARE_TIMERS] = {
 */
 
 
-void HAL_timer_start (uint8_t timer_num, uint32_t frequency) {
-  Tc *tc = TimerConfig [timer_num].pTimerRegs;
-  IRQn_Type irq = TimerConfig [timer_num].IRQ_Id;
-  uint32_t channel = TimerConfig [timer_num].channel;
+void HAL_timer_start(const uint8_t timer_num, const uint32_t frequency) {
+  Tc *tc = TimerConfig[timer_num].pTimerRegs;
+  IRQn_Type irq = TimerConfig[timer_num].IRQ_Id;
+  uint32_t channel = TimerConfig[timer_num].channel;
 
   pmc_set_writeprotect(false);
   pmc_enable_periph_clk((uint32_t)irq);
-  NVIC_SetPriority (irq, TimerConfig [timer_num].priority);
+  NVIC_SetPriority(irq, TimerConfig [timer_num].priority);
 
-  TC_Configure (tc, channel, TC_CMR_WAVE | TC_CMR_WAVSEL_UP_RC | TC_CMR_TCCLKS_TIMER_CLOCK1);
+  TC_Configure(tc, channel, TC_CMR_WAVE | TC_CMR_WAVSEL_UP_RC | TC_CMR_TCCLKS_TIMER_CLOCK1);
 
-  TC_SetRC(tc, channel, VARIANT_MCK/2/frequency);
+  TC_SetRC(tc, channel, VARIANT_MCK / 2 / frequency);
   TC_Start(tc, channel);
 
   // enable interrupt on RC compare
@@ -112,25 +112,25 @@ void HAL_timer_start (uint8_t timer_num, uint32_t frequency) {
   NVIC_EnableIRQ(irq);
 }
 
-void HAL_timer_enable_interrupt (uint8_t timer_num) {
-  const tTimerConfig *pConfig = &TimerConfig [timer_num];
-  pConfig->pTimerRegs->TC_CHANNEL [pConfig->channel].TC_IER = TC_IER_CPCS;
+void HAL_timer_enable_interrupt(const uint8_t timer_num) {
+  const tTimerConfig *pConfig = &TimerConfig[timer_num];
+  pConfig->pTimerRegs->TC_CHANNEL[pConfig->channel].TC_IER = TC_IER_CPCS;
 }
 
-void HAL_timer_disable_interrupt (uint8_t timer_num) {
-  const tTimerConfig *pConfig = &TimerConfig [timer_num];
-  pConfig->pTimerRegs->TC_CHANNEL [pConfig->channel].TC_IDR = TC_IDR_CPCS;
+void HAL_timer_disable_interrupt(const uint8_t timer_num) {
+  const tTimerConfig *pConfig = &TimerConfig[timer_num];
+  pConfig->pTimerRegs->TC_CHANNEL[pConfig->channel].TC_IDR = TC_IDR_CPCS;
 }
 
 #if 0
-  void HAL_timer_set_count (uint8_t timer_num, uint32_t count) {
-    const tTimerConfig *pConfig = &TimerConfig [timer_num];
-    TC_SetRC (pConfig->pTimerRegs, pConfig->channel, count);
+  void HAL_timer_set_count(const uint8_t timer_num, const uint32_t count) {
+    const tTimerConfig *pConfig = &TimerConfig[timer_num];
+    TC_SetRC(pConfig->pTimerRegs, pConfig->channel, count);
   }
 
-  void HAL_timer_isr_prologue (uint8_t timer_num) {
-    const tTimerConfig *pConfig = &TimerConfig [timer_num];
-    TC_GetStatus (pConfig->pTimerRegs, pConfig->channel);
+  void HAL_timer_isr_prologue(const uint8_t timer_num) {
+    const tTimerConfig *pConfig = &TimerConfig[timer_num];
+    TC_GetStatus(pConfig->pTimerRegs, pConfig->channel);
   }
 #endif
 
diff --git a/Marlin/src/HAL/HAL_DUE/HAL_timers_Due.h b/Marlin/src/HAL/HAL_DUE/HAL_timers_Due.h
index c5c1b68fc..64a0e72a3 100644
--- a/Marlin/src/HAL/HAL_DUE/HAL_timers_Due.h
+++ b/Marlin/src/HAL/HAL_DUE/HAL_timers_Due.h
@@ -53,14 +53,14 @@
 
 #define TEMP_TIMER_FREQUENCY   1000 // temperature interrupt frequency
 
-#define ENABLE_STEPPER_DRIVER_INTERRUPT() HAL_timer_enable_interrupt (STEP_TIMER_NUM)
-#define DISABLE_STEPPER_DRIVER_INTERRUPT()  HAL_timer_disable_interrupt (STEP_TIMER_NUM)
+#define ENABLE_STEPPER_DRIVER_INTERRUPT() HAL_timer_enable_interrupt(STEP_TIMER_NUM)
+#define DISABLE_STEPPER_DRIVER_INTERRUPT()  HAL_timer_disable_interrupt(STEP_TIMER_NUM)
 
-#define ENABLE_TEMPERATURE_INTERRUPT()  HAL_timer_enable_interrupt (TEMP_TIMER_NUM)
-#define DISABLE_TEMPERATURE_INTERRUPT() HAL_timer_disable_interrupt (TEMP_TIMER_NUM)
+#define ENABLE_TEMPERATURE_INTERRUPT()  HAL_timer_enable_interrupt(TEMP_TIMER_NUM)
+#define DISABLE_TEMPERATURE_INTERRUPT() HAL_timer_disable_interrupt(TEMP_TIMER_NUM)
+
+#define HAL_ENABLE_ISRs() do { if (thermalManager.in_temp_isr) DISABLE_TEMPERATURE_INTERRUPT(); else ENABLE_TEMPERATURE_INTERRUPT(); ENABLE_STEPPER_DRIVER_INTERRUPT(); } while(0)
 
-#define HAL_ENABLE_ISRs() do { if (thermalManager.in_temp_isr)DISABLE_TEMPERATURE_INTERRUPT(); else ENABLE_TEMPERATURE_INTERRUPT(); ENABLE_STEPPER_DRIVER_INTERRUPT(); } while(0)
-//
 #define HAL_STEP_TIMER_ISR  void TC3_Handler()
 #define HAL_TEMP_TIMER_ISR  void TC4_Handler()
 
@@ -85,29 +85,29 @@ extern const tTimerConfig TimerConfig[];
 // Public functions
 // --------------------------------------------------------------------------
 
-void HAL_timer_start (uint8_t timer_num, uint32_t frequency);
+void HAL_timer_start(const uint8_t timer_num, const uint32_t frequency);
 
-static FORCE_INLINE void HAL_timer_set_count (uint8_t timer_num, uint32_t count) {
+static FORCE_INLINE void HAL_timer_set_count(const uint8_t timer_num, const uint32_t count) {
   const tTimerConfig *pConfig = &TimerConfig[timer_num];
   pConfig->pTimerRegs->TC_CHANNEL[pConfig->channel].TC_RC = count;
 }
 
-static FORCE_INLINE HAL_TIMER_TYPE HAL_timer_get_count (uint8_t timer_num) {
+static FORCE_INLINE HAL_TIMER_TYPE HAL_timer_get_count(const uint8_t timer_num) {
   const tTimerConfig *pConfig = &TimerConfig[timer_num];
   return pConfig->pTimerRegs->TC_CHANNEL[pConfig->channel].TC_RC;
 }
 
-static FORCE_INLINE uint32_t HAL_timer_get_current_count(uint8_t timer_num) {
+static FORCE_INLINE uint32_t HAL_timer_get_current_count(const uint8_t timer_num) {
   const tTimerConfig *pConfig = &TimerConfig[timer_num];
   return pConfig->pTimerRegs->TC_CHANNEL[pConfig->channel].TC_CV;
 }
 
-void HAL_timer_enable_interrupt(uint8_t timer_num);
-void HAL_timer_disable_interrupt(uint8_t timer_num);
+void HAL_timer_enable_interrupt(const uint8_t timer_num);
+void HAL_timer_disable_interrupt(const uint8_t timer_num);
 
-//void HAL_timer_isr_prologue (uint8_t timer_num);
+//void HAL_timer_isr_prologue(const uint8_t timer_num);
 
-static FORCE_INLINE void HAL_timer_isr_prologue(uint8_t timer_num) {
+static FORCE_INLINE void HAL_timer_isr_prologue(const uint8_t timer_num) {
   const tTimerConfig *pConfig = &TimerConfig[timer_num];
   // Reading the status register clears the interrupt flag
   pConfig->pTimerRegs->TC_CHANNEL[pConfig->channel].TC_SR;
diff --git a/Marlin/src/HAL/HAL_LPC1768/HAL_timers.cpp b/Marlin/src/HAL/HAL_LPC1768/HAL_timers.cpp
index c4374b914..3613f8a40 100644
--- a/Marlin/src/HAL/HAL_LPC1768/HAL_timers.cpp
+++ b/Marlin/src/HAL/HAL_LPC1768/HAL_timers.cpp
@@ -32,62 +32,53 @@
 #include "HAL_timers.h"
 
 void HAL_timer_init(void) {
-  LPC_SC->PCONP |= (0x1 << 0x1);  // power on timer0
+  SBI(LPC_SC->PCONP, 1);  // power on timer0
   LPC_TIM0->PR = ((HAL_TIMER_RATE / HAL_STEPPER_TIMER_RATE) - 1); // Use prescaler to set frequency if needed
 
-  LPC_SC->PCONP |= (0x1 << 0x2);  // power on timer1
+  SBI(LPC_SC->PCONP, 2);  // power on timer1
   LPC_TIM1->PR = ((HAL_TIMER_RATE / 1000000) - 1);
 }
 
-void HAL_timer_start(uint8_t timer_num, uint32_t frequency) {
-  switch(timer_num) {
-  case 0:
-    LPC_TIM0->MCR = 3;              // Match on MR0, reset on MR0
-    LPC_TIM0->MR0 = (uint32_t)(HAL_STEPPER_TIMER_RATE / frequency); // Match value (period) to set frequency
-    LPC_TIM0->TCR = (1 << 0);       // enable
-    break;
-  case 1:
-    LPC_TIM1->MCR = 3;
-    LPC_TIM1->MR0 = (uint32_t)(HAL_TEMP_TIMER_RATE / frequency);;
-    LPC_TIM1->TCR = (1 << 0);
-    break;
-  default:
-    return;
+void HAL_timer_start(const uint8_t timer_num, const uint32_t frequency) {
+  switch (timer_num) {
+    case 0:
+      LPC_TIM0->MCR = 3;              // Match on MR0, reset on MR0
+      LPC_TIM0->MR0 = (uint32_t)(HAL_STEPPER_TIMER_RATE / frequency); // Match value (period) to set frequency
+      LPC_TIM0->TCR = _BV(0);       // enable
+      break;
+    case 1:
+      LPC_TIM1->MCR = 3;
+      LPC_TIM1->MR0 = (uint32_t)(HAL_TEMP_TIMER_RATE / frequency);;
+      LPC_TIM1->TCR = _BV(0);
+      break;
+    default: break;
   }
 }
 
-void HAL_timer_enable_interrupt (uint8_t timer_num) {
-  switch(timer_num) {
-  case 0:
-    NVIC_EnableIRQ(TIMER0_IRQn);     // Enable interrupt handler
-    NVIC_SetPriority(TIMER0_IRQn, NVIC_EncodePriority(0, 1, 0));
-    break;
-  case 1:
-    NVIC_EnableIRQ(TIMER1_IRQn);
-    NVIC_SetPriority(TIMER1_IRQn, NVIC_EncodePriority(0, 2, 0));
-    break;
+void HAL_timer_enable_interrupt(const uint8_t timer_num) {
+  switch (timer_num) {
+    case 0:
+      NVIC_EnableIRQ(TIMER0_IRQn); // Enable interrupt handler
+      NVIC_SetPriority(TIMER0_IRQn, NVIC_EncodePriority(0, 1, 0));
+      break;
+    case 1:
+      NVIC_EnableIRQ(TIMER1_IRQn);
+      NVIC_SetPriority(TIMER1_IRQn, NVIC_EncodePriority(0, 2, 0));
+      break;
   }
 }
 
-void HAL_timer_disable_interrupt (uint8_t timer_num) {
-  switch(timer_num) {
-  case 0:
-    NVIC_DisableIRQ(TIMER0_IRQn);     // disable interrupt handler
-    break;
-  case 1:
-    NVIC_DisableIRQ(TIMER1_IRQn);
-    break;
+void HAL_timer_disable_interrupt(const uint8_t timer_num) {
+  switch (timer_num) {
+    case 0: NVIC_DisableIRQ(TIMER0_IRQn); break; // disable interrupt handler
+    case 1: NVIC_DisableIRQ(TIMER1_IRQn); break;
   }
 }
 
-void HAL_timer_isr_prologue (uint8_t timer_num) {
-  switch(timer_num) {
-  case 0:
-    LPC_TIM0->IR |= 1; //Clear the Interrupt
-    break;
-  case 1:
-    LPC_TIM1->IR |= 1;
-    break;
+void HAL_timer_isr_prologue(const uint8_t timer_num) {
+  switch (timer_num) {
+    case 0: SBI(LPC_TIM0->IR, 0); break; // Clear the Interrupt
+    case 1: SBI(LPC_TIM1->IR, 0); break;
   }
 }
 
diff --git a/Marlin/src/HAL/HAL_LPC1768/HAL_timers.h b/Marlin/src/HAL/HAL_LPC1768/HAL_timers.h
index f93ea6229..dcbaec67a 100644
--- a/Marlin/src/HAL/HAL_LPC1768/HAL_timers.h
+++ b/Marlin/src/HAL/HAL_LPC1768/HAL_timers.h
@@ -53,14 +53,13 @@
 #define HAL_TEMP_TIMER_RATE    1000000
 #define TEMP_TIMER_FREQUENCY   1000 // temperature interrupt frequency
 
-#define ENABLE_STEPPER_DRIVER_INTERRUPT() HAL_timer_enable_interrupt (STEP_TIMER_NUM)
-#define DISABLE_STEPPER_DRIVER_INTERRUPT()  HAL_timer_disable_interrupt (STEP_TIMER_NUM)
+#define ENABLE_STEPPER_DRIVER_INTERRUPT() HAL_timer_enable_interrupt(STEP_TIMER_NUM)
+#define DISABLE_STEPPER_DRIVER_INTERRUPT() HAL_timer_disable_interrupt(STEP_TIMER_NUM)
+#define ENABLE_TEMPERATURE_INTERRUPT() HAL_timer_enable_interrupt(TEMP_TIMER_NUM)
+#define DISABLE_TEMPERATURE_INTERRUPT() HAL_timer_disable_interrupt(TEMP_TIMER_NUM)
 
-#define ENABLE_TEMPERATURE_INTERRUPT()  HAL_timer_enable_interrupt (TEMP_TIMER_NUM)
-#define DISABLE_TEMPERATURE_INTERRUPT() HAL_timer_disable_interrupt (TEMP_TIMER_NUM)
+#define HAL_ENABLE_ISRs() do { if (thermalManager.in_temp_isr) DISABLE_TEMPERATURE_INTERRUPT(); else ENABLE_TEMPERATURE_INTERRUPT(); ENABLE_STEPPER_DRIVER_INTERRUPT(); } while(0)
 
-#define HAL_ENABLE_ISRs() do { if (thermalManager.in_temp_isr)DISABLE_TEMPERATURE_INTERRUPT(); else ENABLE_TEMPERATURE_INTERRUPT(); ENABLE_STEPPER_DRIVER_INTERRUPT(); } while(0)
-//
 #define HAL_STEP_TIMER_ISR  extern "C" void TIMER0_IRQHandler(void)
 #define HAL_TEMP_TIMER_ISR  extern "C" void TIMER1_IRQHandler(void)
 
@@ -75,47 +74,34 @@
 // --------------------------------------------------------------------------
 // Public functions
 // --------------------------------------------------------------------------
-void HAL_timer_init (void);
-void HAL_timer_start (uint8_t timer_num, uint32_t frequency);
-
-static FORCE_INLINE void HAL_timer_set_count (uint8_t timer_num, HAL_TIMER_TYPE count) {
-  switch(timer_num) {
-  case 0:
-    LPC_TIM0->MR0 = count;
-    break;
-  case 1:
-    LPC_TIM1->MR0 = count;
-    break;
-  default:
-    return;
+void HAL_timer_init(void);
+void HAL_timer_start(const uint8_t timer_num, const uint32_t frequency);
+
+static FORCE_INLINE void HAL_timer_set_count(const uint8_t timer_num, const HAL_TIMER_TYPE count) {
+  switch (timer_num) {
+    case 0: LPC_TIM0->MR0 = count; break;
+    case 1: LPC_TIM1->MR0 = count; break;
   }
 }
 
-static FORCE_INLINE HAL_TIMER_TYPE HAL_timer_get_count (uint8_t timer_num) {
-  switch(timer_num) {
-  case 0:
-    return LPC_TIM0->MR0;
-  case 1:
-    return LPC_TIM1->MR0;
-  default:
-    return 0;
+static FORCE_INLINE HAL_TIMER_TYPE HAL_timer_get_count(const uint8_t timer_num) {
+  switch (timer_num) {
+    case 0: return LPC_TIM0->MR0;
+    case 1: return LPC_TIM1->MR0;
   }
+  return 0;
 }
 
-static FORCE_INLINE HAL_TIMER_TYPE HAL_timer_get_current_count(uint8_t timer_num) {
-  switch(timer_num) {
-  case 0:
-    return LPC_TIM0->TC;
-  case 1:
-    return LPC_TIM1->TC;
-  default:
-    return 0;
+static FORCE_INLINE HAL_TIMER_TYPE HAL_timer_get_current_count(const uint8_t timer_num) {
+  switch (timer_num) {
+    case 0: return LPC_TIM0->TC;
+    case 1: return LPC_TIM1->TC;
   }
+  return 0;
 }
 
-void HAL_timer_enable_interrupt(uint8_t timer_num);
-void HAL_timer_disable_interrupt(uint8_t timer_num);
-void HAL_timer_isr_prologue (uint8_t timer_num);
-
+void HAL_timer_enable_interrupt(const uint8_t timer_num);
+void HAL_timer_disable_interrupt(const uint8_t timer_num);
+void HAL_timer_isr_prologue(const uint8_t timer_num);
 
 #endif // _HAL_TIMERS_DUE_H
diff --git a/Marlin/src/HAL/HAL_LPC1768/watchdog.cpp b/Marlin/src/HAL/HAL_LPC1768/watchdog.cpp
index a3b9ac3cc..bdc62b5ff 100644
--- a/Marlin/src/HAL/HAL_LPC1768/watchdog.cpp
+++ b/Marlin/src/HAL/HAL_LPC1768/watchdog.cpp
@@ -38,8 +38,8 @@ void HAL_clear_reset_source(void) {
   WDT_ClrTimeOutFlag();
 }
 
-uint8_t HAL_get_reset_source (void) {
-  if(WDT_ReadTimeOutFlag() & 1) return RST_WATCHDOG;
+uint8_t HAL_get_reset_source(void) {
+  if (TEST(WDT_ReadTimeOutFlag(), 0)) return RST_WATCHDOG;
   return RST_POWER_ON;
 }
 
@@ -50,4 +50,4 @@ void watchdog_reset() {
 
 #endif // USE_WATCHDOG
 
-#endif
+#endif // TARGET_LPC1768
diff --git a/Marlin/src/HAL/HAL_TEENSY35_36/HAL_Teensy.cpp b/Marlin/src/HAL/HAL_TEENSY35_36/HAL_Teensy.cpp
index 859b76459..c6490495c 100644
--- a/Marlin/src/HAL/HAL_TEENSY35_36/HAL_Teensy.cpp
+++ b/Marlin/src/HAL/HAL_TEENSY35_36/HAL_Teensy.cpp
@@ -31,7 +31,6 @@
 
 uint16_t HAL_adc_result;
 
-
 static const uint8_t pin2sc1a[] = {
   5, 14, 8, 9, 13, 12, 6, 7, 15, 4, 3, 19+128, 14+128, 15+128, // 0-13 -> A0-A13
   5, 14, 8, 9, 13, 12, 6, 7, 15, 4, // 14-23 are A0-A9
@@ -49,45 +48,31 @@ static const uint8_t pin2sc1a[] = {
 };
 
 /*
-// disable interrupts
-void cli(void)
-{
-	noInterrupts();
-}
+  // disable interrupts
+  void cli(void) { noInterrupts(); }
 
-// enable interrupts
-void sei(void)
-{
-	interrupts();
-}
+  // enable interrupts
+  void sei(void) { interrupts(); }
 */
+
 void HAL_adc_init() {
   analog_init();
   while (ADC0_SC3 & ADC_SC3_CAL) {}; // Wait for calibration to finish
   NVIC_ENABLE_IRQ(IRQ_FTM1);
 }
 
-void HAL_clear_reset_source (void)
-{ }
+void HAL_clear_reset_source(void) { }
 
-uint8_t HAL_get_reset_source (void)
-{
-  switch ( RCM_SRS0 )
-  {
+uint8_t HAL_get_reset_source(void) {
+  switch (RCM_SRS0) {
     case 128: return RST_POWER_ON; break;
     case 64: return RST_EXTERNAL; break;
     case 32: return RST_WATCHDOG; break;
-//  case 8: return RST_LOSS_OF_LOCK; break;
-//  case 4: return RST_LOSS_OF_CLOCK; break;
-//  case 2: return RST_LOW_VOLTAGE; break;
-    default:
-      return 0;
+    // case 8: return RST_LOSS_OF_LOCK; break;
+    // case 4: return RST_LOSS_OF_CLOCK; break;
+    // case 2: return RST_LOW_VOLTAGE; break;
   }
-}
-
-void _delay_ms (int delay_ms)
-{
-	delay (delay_ms);
+  return 0;
 }
 
 extern "C" {
@@ -105,15 +90,8 @@ extern "C" {
   }
 }
 
-void HAL_adc_start_conversion (uint8_t adc_pin)
-{
-	ADC0_SC1A = pin2sc1a[adc_pin];
-}
+void HAL_adc_start_conversion(const uint8_t adc_pin) { ADC0_SC1A = pin2sc1a[adc_pin]; }
 
-uint16_t HAL_adc_get_result(void)
-{
-	return ADC0_RA;
-}
+uint16_t HAL_adc_get_result(void) { return ADC0_RA; }
 
 #endif // __MK64FX512__ || __MK66FX1M0__
-
diff --git a/Marlin/src/HAL/HAL_TEENSY35_36/HAL_Teensy.h b/Marlin/src/HAL/HAL_TEENSY35_36/HAL_Teensy.h
index 319406ee2..51311fece 100644
--- a/Marlin/src/HAL/HAL_TEENSY35_36/HAL_Teensy.h
+++ b/Marlin/src/HAL/HAL_TEENSY35_36/HAL_Teensy.h
@@ -23,7 +23,6 @@
  * Description: HAL for Teensy 3.5 and Teensy 3.6
  */
 
-
 #ifndef _HAL_TEENSY_H
 #define _HAL_TEENSY_H
 
@@ -64,8 +63,6 @@
 
 #define HAL_SERVO_LIB libServo
 
-//#define _BV(bit) 	(1 << (bit))
-
 #ifndef analogInputToDigitalPin
   #define analogInputToDigitalPin(p) ((p < 12u) ? (p) + 54u : -1)
 #endif
@@ -73,7 +70,6 @@
 #define CRITICAL_SECTION_START  unsigned char _sreg = SREG; cli();
 #define CRITICAL_SECTION_END    SREG = _sreg;
 
-
 // On AVR this is in math.h?
 #define square(x) ((x)*(x))
 
@@ -96,12 +92,12 @@
 #define RST_BACKUP     64
 
 /** clear reset reason */
-void HAL_clear_reset_source (void);
+void HAL_clear_reset_source(void);
 
 /** reset reason */
-uint8_t HAL_get_reset_source (void);
+uint8_t HAL_get_reset_source(void);
 
-void _delay_ms(int delay);
+FORCE_INLINE void _delay_ms(const int delay_ms) { delay(delay_ms); }
 
 extern "C" {
   int freeMemory(void);
@@ -124,21 +120,21 @@ void HAL_adc_init();
 
 #define HAL_ANALOG_SELECT(pin) NOOP;
 
-void HAL_adc_start_conversion (uint8_t adc_pin);
+void HAL_adc_start_conversion(uint8_t adc_pin);
 
 uint16_t HAL_adc_get_result(void);
 
 /*
-uint16_t HAL_getAdcReading(uint8_t chan);
+  uint16_t HAL_getAdcReading(uint8_t chan);
 
-void HAL_startAdcConversion(uint8_t chan);
-uint8_t HAL_pinToAdcChannel(int pin);
+  void HAL_startAdcConversion(uint8_t chan);
+  uint8_t HAL_pinToAdcChannel(int pin);
 
-uint16_t HAL_getAdcFreerun(uint8_t chan, bool wait_for_conversion = false);
-//uint16_t HAL_getAdcSuperSample(uint8_t chan);
+  uint16_t HAL_getAdcFreerun(uint8_t chan, bool wait_for_conversion = false);
+  //uint16_t HAL_getAdcSuperSample(uint8_t chan);
 
-void HAL_enable_AdcFreerun(void);
-//void HAL_disable_AdcFreerun(uint8_t chan);
+  void HAL_enable_AdcFreerun(void);
+  //void HAL_disable_AdcFreerun(uint8_t chan);
 */
 
 // --------------------------------------------------------------------------
@@ -146,4 +142,3 @@ void HAL_enable_AdcFreerun(void);
 // --------------------------------------------------------------------------
 
 #endif // _HAL_TEENSY_H
-
diff --git a/Marlin/src/HAL/HAL_TEENSY35_36/HAL_timers_Teensy.cpp b/Marlin/src/HAL/HAL_TEENSY35_36/HAL_timers_Teensy.cpp
index 58258778b..931c75bdc 100644
--- a/Marlin/src/HAL/HAL_TEENSY35_36/HAL_timers_Teensy.cpp
+++ b/Marlin/src/HAL/HAL_TEENSY35_36/HAL_timers_Teensy.cpp
@@ -30,65 +30,55 @@
 #include "HAL_timers_Teensy.h"
 
 
-void HAL_timer_start (uint8_t timer_num, uint32_t frequency) {
+void HAL_timer_start(const uint8_t timer_num, const uint32_t frequency) {
   switch (timer_num) {
-  case 0:
-    FTM0_MODE = FTM_MODE_WPDIS | FTM_MODE_FTMEN;
-    FTM0_SC = 0x00; // Set this to zero before changing the modulus
-    FTM0_CNT = 0x0000; // Reset the count to zero
-    FTM0_MOD = 0xFFFF; // max modulus = 65535
-    FTM0_C0V = FTM0_TIMER_RATE / frequency; // Initial FTM Channel 0 compare value
-    FTM0_SC = (FTM_SC_CLKS(0b1)&FTM_SC_CLKS_MASK) | (FTM_SC_PS(FTM0_TIMER_PRESCALE_BITS)&FTM_SC_PS_MASK); // Bus clock 60MHz divided by prescaler 8
-    FTM0_C0SC = FTM_CSC_CHIE | FTM_CSC_MSA | FTM_CSC_ELSA;
-    break;
-  case 1:
-    FTM1_MODE = FTM_MODE_WPDIS | FTM_MODE_FTMEN; // Disable write protection, Enable FTM1
-    FTM1_SC = 0x00; // Set this to zero before changing the modulus
-    FTM1_CNT = 0x0000; // Reset the count to zero
-    FTM1_MOD = 0xFFFF; // max modulus = 65535
-    FTM1_C0V = FTM1_TIMER_RATE / frequency; // Initial FTM Channel 0 compare value 65535
-    FTM1_SC = (FTM_SC_CLKS(0b1)&FTM_SC_CLKS_MASK) | (FTM_SC_PS(FTM1_TIMER_PRESCALE_BITS)&FTM_SC_PS_MASK); // Bus clock 60MHz divided by prescaler 4
-    FTM1_C0SC = FTM_CSC_CHIE | FTM_CSC_MSA | FTM_CSC_ELSA;
-    break;
-  default:
-    break;
+    case 0:
+      FTM0_MODE = FTM_MODE_WPDIS | FTM_MODE_FTMEN;
+      FTM0_SC = 0x00; // Set this to zero before changing the modulus
+      FTM0_CNT = 0x0000; // Reset the count to zero
+      FTM0_MOD = 0xFFFF; // max modulus = 65535
+      FTM0_C0V = FTM0_TIMER_RATE / frequency; // Initial FTM Channel 0 compare value
+      FTM0_SC = (FTM_SC_CLKS(0b1) & FTM_SC_CLKS_MASK) | (FTM_SC_PS(FTM0_TIMER_PRESCALE_BITS) & FTM_SC_PS_MASK); // Bus clock 60MHz divided by prescaler 8
+      FTM0_C0SC = FTM_CSC_CHIE | FTM_CSC_MSA | FTM_CSC_ELSA;
+      break;
+    case 1:
+      FTM1_MODE = FTM_MODE_WPDIS | FTM_MODE_FTMEN; // Disable write protection, Enable FTM1
+      FTM1_SC = 0x00; // Set this to zero before changing the modulus
+      FTM1_CNT = 0x0000; // Reset the count to zero
+      FTM1_MOD = 0xFFFF; // max modulus = 65535
+      FTM1_C0V = FTM1_TIMER_RATE / frequency; // Initial FTM Channel 0 compare value 65535
+      FTM1_SC = (FTM_SC_CLKS(0b1) & FTM_SC_CLKS_MASK) | (FTM_SC_PS(FTM1_TIMER_PRESCALE_BITS) & FTM_SC_PS_MASK); // Bus clock 60MHz divided by prescaler 4
+      FTM1_C0SC = FTM_CSC_CHIE | FTM_CSC_MSA | FTM_CSC_ELSA;
+      break;
   }
 }
 
-void HAL_timer_enable_interrupt (uint8_t timer_num)
-{
+void HAL_timer_enable_interrupt(const uint8_t timer_num) {
   switch(timer_num) {
-  case 0: NVIC_ENABLE_IRQ(IRQ_FTM0); break;
-  case 1: NVIC_ENABLE_IRQ(IRQ_FTM1); break;
-  default:
-    break;
+    case 0: NVIC_ENABLE_IRQ(IRQ_FTM0); break;
+    case 1: NVIC_ENABLE_IRQ(IRQ_FTM1); break;
   }
 }
 
-void HAL_timer_disable_interrupt (uint8_t timer_num)
-{
+void HAL_timer_disable_interrupt(const uint8_t timer_num) {
   switch (timer_num) {
-  case 0: NVIC_DISABLE_IRQ(IRQ_FTM0); break;
-  case 1: NVIC_DISABLE_IRQ(IRQ_FTM1); break;
-  default:
-    break;
+    case 0: NVIC_DISABLE_IRQ(IRQ_FTM0); break;
+    case 1: NVIC_DISABLE_IRQ(IRQ_FTM1); break;
   }
 }
 
-void HAL_timer_isr_prologue(uint8_t timer_num) {
+void HAL_timer_isr_prologue(const uint8_t timer_num) {
   switch(timer_num) {
-  case 0:
-    FTM0_CNT = 0x0000;
-    FTM0_SC &= ~FTM_SC_TOF; // Clear FTM Overflow flag
-    FTM0_C0SC &= ~FTM_CSC_CHF; // Clear FTM Channel Compare flag
-    break;
-  case 1:
-    FTM1_CNT = 0x0000;
-    FTM1_SC &= ~FTM_SC_TOF; // Clear FTM Overflow flag
-    FTM1_C0SC &= ~FTM_CSC_CHF; // Clear FTM Channel Compare flag
-    break;
-  default:
-    break;
+    case 0:
+      FTM0_CNT = 0x0000;
+      FTM0_SC &= ~FTM_SC_TOF; // Clear FTM Overflow flag
+      FTM0_C0SC &= ~FTM_CSC_CHF; // Clear FTM Channel Compare flag
+      break;
+    case 1:
+      FTM1_CNT = 0x0000;
+      FTM1_SC &= ~FTM_SC_TOF; // Clear FTM Overflow flag
+      FTM1_C0SC &= ~FTM_CSC_CHF; // Clear FTM Channel Compare flag
+      break;
   }
 }
 
diff --git a/Marlin/src/HAL/HAL_TEENSY35_36/HAL_timers_Teensy.h b/Marlin/src/HAL/HAL_TEENSY35_36/HAL_timers_Teensy.h
index b7a44b900..04a09b15e 100644
--- a/Marlin/src/HAL/HAL_TEENSY35_36/HAL_timers_Teensy.h
+++ b/Marlin/src/HAL/HAL_TEENSY35_36/HAL_timers_Teensy.h
@@ -52,8 +52,8 @@
 #define FTM0_TIMER_PRESCALE_BITS 0b011
 #define FTM1_TIMER_PRESCALE_BITS 0b010
 
-#define FTM0_TIMER_RATE F_BUS/FTM0_TIMER_PRESCALE // 60MHz / 8 = 7500kHz
-#define FTM1_TIMER_RATE F_BUS/FTM1_TIMER_PRESCALE // 60MHz / 4 = 15MHz
+#define FTM0_TIMER_RATE (F_BUS / FTM0_TIMER_PRESCALE) // 60MHz / 8 = 7500kHz
+#define FTM1_TIMER_RATE (F_BUS / FTM1_TIMER_PRESCALE) // 60MHz / 4 = 15MHz
 
 #define STEPPER_TIMER STEP_TIMER_NUM // Alias?
 #define STEPPER_TIMER_PRESCALE 0 // Not defined anywhere else!
@@ -64,46 +64,45 @@
 
 #define TEMP_TIMER_FREQUENCY   1000
 
-#define ENABLE_STEPPER_DRIVER_INTERRUPT() HAL_timer_enable_interrupt (STEP_TIMER_NUM)
-#define DISABLE_STEPPER_DRIVER_INTERRUPT()  HAL_timer_disable_interrupt (STEP_TIMER_NUM)
-#define ENABLE_TEMPERATURE_INTERRUPT() HAL_timer_enable_interrupt (TEMP_TIMER_NUM)
-#define DISABLE_TEMPERATURE_INTERRUPT()  HAL_timer_disable_interrupt (TEMP_TIMER_NUM)
+#define ENABLE_STEPPER_DRIVER_INTERRUPT() HAL_timer_enable_interrupt(STEP_TIMER_NUM)
+#define DISABLE_STEPPER_DRIVER_INTERRUPT() HAL_timer_disable_interrupt(STEP_TIMER_NUM)
+#define ENABLE_TEMPERATURE_INTERRUPT() HAL_timer_enable_interrupt(TEMP_TIMER_NUM)
+#define DISABLE_TEMPERATURE_INTERRUPT() HAL_timer_disable_interrupt(TEMP_TIMER_NUM)
 
 #define HAL_STEP_TIMER_ISR  extern "C" void ftm0_isr(void) //void TC3_Handler()
 #define HAL_TEMP_TIMER_ISR  extern "C" void ftm1_isr(void) //void TC4_Handler()
 
-#define HAL_ENABLE_ISRs() do { if (thermalManager.in_temp_isr)DISABLE_TEMPERATURE_INTERRUPT(); else ENABLE_TEMPERATURE_INTERRUPT(); ENABLE_STEPPER_DRIVER_INTERRUPT(); } while(0)
+#define HAL_ENABLE_ISRs() do { if (thermalManager.in_temp_isr) DISABLE_TEMPERATURE_INTERRUPT(); else ENABLE_TEMPERATURE_INTERRUPT(); ENABLE_STEPPER_DRIVER_INTERRUPT(); } while(0)
 
-void HAL_timer_start (uint8_t timer_num, uint32_t frequency);
+void HAL_timer_start(const uint8_t timer_num, const uint32_t frequency);
 
-static FORCE_INLINE void HAL_timer_set_count (uint8_t timer_num, uint32_t count) {
+static FORCE_INLINE void HAL_timer_set_count(const uint8_t timer_num, const uint32_t count) {
   switch(timer_num) {
-  case 0: FTM0_C0V = count; break;
-  case 1: FTM1_C0V = count; break;
-  default: break;
+    case 0: FTM0_C0V = count; break;
+    case 1: FTM1_C0V = count; break;
   }
 }
 
-static FORCE_INLINE HAL_TIMER_TYPE HAL_timer_get_count (uint8_t timer_num) {
+static FORCE_INLINE HAL_TIMER_TYPE HAL_timer_get_count(const uint8_t timer_num) {
   switch(timer_num) {
-  case 0: return FTM0_C0V;
-  case 1: return FTM1_C0V;
-  default: return 0;
+    case 0: return FTM0_C0V;
+    case 1: return FTM1_C0V;
   }
+  return 0;
 }
 
-static FORCE_INLINE uint32_t HAL_timer_get_current_count(uint8_t timer_num) {
+static FORCE_INLINE uint32_t HAL_timer_get_current_count(const uint8_t timer_num) {
   switch(timer_num) {
-  case 0: return FTM0_CNT;
-  case 1: return FTM1_CNT;
-  default: return 0;
+    case 0: return FTM0_CNT;
+    case 1: return FTM1_CNT;
   }
+  return 0;
 }
 
-void HAL_timer_enable_interrupt (uint8_t timer_num);
-void HAL_timer_disable_interrupt (uint8_t timer_num);
+void HAL_timer_enable_interrupt(const uint8_t timer_num);
+void HAL_timer_disable_interrupt(const uint8_t timer_num);
 
-void HAL_timer_isr_prologue(uint8_t timer_num);
+void HAL_timer_isr_prologue(const uint8_t timer_num);
 
 #endif // _HAL_TIMERS_TEENSY_H
 
diff --git a/Marlin/stepper.cpp b/Marlin/stepper.cpp
index e1fa29734..1a68f7f2f 100644
--- a/Marlin/stepper.cpp
+++ b/Marlin/stepper.cpp
@@ -1155,7 +1155,7 @@ void Stepper::init() {
   TCNT1 = 0;
 #else
   // Init Stepper ISR to 122 Hz for quick starting
-  HAL_timer_start (STEP_TIMER_NUM, 122);
+  HAL_timer_start(STEP_TIMER_NUM, 122);
 #endif
 
   ENABLE_STEPPER_DRIVER_INTERRUPT();
diff --git a/Marlin/temperature.cpp b/Marlin/temperature.cpp
index dfda329af..33df993cc 100644
--- a/Marlin/temperature.cpp
+++ b/Marlin/temperature.cpp
@@ -1081,8 +1081,8 @@ void Temperature::init() {
     OCR0B = 128;
     SBI(TIMSK0, OCIE0B);
   #else
-    HAL_timer_start (TEMP_TIMER_NUM, TEMP_TIMER_FREQUENCY);
-    HAL_timer_enable_interrupt (TEMP_TIMER_NUM);
+    HAL_timer_start(TEMP_TIMER_NUM, TEMP_TIMER_FREQUENCY);
+    HAL_timer_enable_interrupt(TEMP_TIMER_NUM);
   #endif
 
   #if HAS_AUTO_FAN_0
@@ -1594,7 +1594,7 @@ void Temperature::set_current_temp_raw() {
  *  - For ENDSTOP_INTERRUPTS_FEATURE check endstops if flagged
  */
 HAL_TEMP_TIMER_ISR {
-  HAL_timer_isr_prologue (TEMP_TIMER_NUM);
+  HAL_timer_isr_prologue(TEMP_TIMER_NUM);
   Temperature::isr();
 }