🧑‍💻 Define isr_float_t to assert a non-FPU float (#23969)

Co-authored-by: Scott Lahteine <thinkyhead@users.noreply.github.com>

Marlin/src/HAL/AVR/HAL.h

     SBI(DIDR0, ch);
   }
 
-  // Begin ADC sampling on the given channel
+  // Begin ADC sampling on the given channel. Called from Temperature::isr!
   static void adc_start(const uint8_t ch) {
     #ifdef MUX5
       ADCSRB = ch > 7 ? _BV(MUX5) : 0;

Marlin/src/HAL/DUE/HAL.h

   // Called by Temperature::init for each sensor at startup
   static void adc_enable(const uint8_t ch) {}
 
-  // Begin ADC sampling on the given channel
+  // Begin ADC sampling on the given channel. Called from Temperature::isr!
   static void adc_start(const uint8_t ch) { adc_result = analogRead(ch); }
 
   // Is the ADC ready for reading?

Marlin/src/HAL/ESP32/HAL.cpp

   const adc1_channel_t chan = get_channel(pin);
   uint32_t mv;
   esp_adc_cal_get_voltage((adc_channel_t)chan, &characteristics[attenuations[chan]], &mv);
-  adc_result = mv * 1023.0f / float(ADC_REFERENCE_VOLTAGE) / 1000.0f;
+
+  adc_result = mv * isr_float_t(1023) / isr_float_t(ADC_REFERENCE_VOLTAGE) / isr_float_t(1000);
 
   // Change the attenuation level based on the new reading
   adc_atten_t atten;

Marlin/src/HAL/ESP32/HAL.h

 // Types
 // ------------------------
 
+typedef double isr_float_t;   // FPU ops are used for single-precision, so use double for ISRs.
 typedef int16_t pin_t;
 
 class Servo;
   // Called by Temperature::init for each sensor at startup
   static void adc_enable(const pin_t pin) {}
 
-  // Begin ADC sampling on the given channel
+  // Begin ADC sampling on the given pin. Called from Temperature::isr!
   static void adc_start(const pin_t pin);
 
   // Is the ADC ready for reading?

Marlin/src/HAL/LPC1768/HAL.h

     FilteredADC::enable_channel(pin);
   }
 
-  // Begin ADC sampling on the given pin
+  // Begin ADC sampling on the given pin. Called from Temperature::isr!
   static uint32_t adc_result;
   static void adc_start(const pin_t pin) {
     adc_result = FilteredADC::read(pin) >> (16 - HAL_ADC_RESOLUTION); // returns 16bit value, reduce to required bits

Marlin/src/HAL/NATIVE_SIM/HAL.h

   // Called by Temperature::init for each sensor at startup
   static void adc_enable(const uint8_t ch);
 
-  // Begin ADC sampling on the given channel
+  // Begin ADC sampling on the given channel. Called from Temperature::isr!
   static void adc_start(const uint8_t ch);
 
   // Is the ADC ready for reading?

Marlin/src/HAL/SAMD51/HAL.h

   // Called by Temperature::init for each sensor at startup
   static void adc_enable(const uint8_t ch) {}
 
-  // Begin ADC sampling on the given channel
+  // Begin ADC sampling on the given pin. Called from Temperature::isr!
   static void adc_start(const pin_t pin);
 
   // Is the ADC ready for reading?

Marlin/src/HAL/STM32/HAL.h

 // Types
 // ------------------------
 
+typedef double isr_float_t;   // FPU ops are used for single-precision, so use double for ISRs.
+
 #ifdef STM32G0B1xx
   typedef int32_t pin_t;
 #else
   // Called by Temperature::init for each sensor at startup
   static void adc_enable(const pin_t pin) { pinMode(pin, INPUT); }
 
-  // Begin ADC sampling on the given channel
+  // Begin ADC sampling on the given pin. Called from Temperature::isr!
   static void adc_start(const pin_t pin) { adc_result = analogRead(pin); }
 
   // Is the ADC ready for reading?

Marlin/src/HAL/STM32F1/HAL.h

   // Called by Temperature::init for each sensor at startup
   static void adc_enable(const pin_t pin) { pinMode(pin, INPUT_ANALOG); }
 
-  // Begin ADC sampling on the given channel
+  // Begin ADC sampling on the given pin. Called from Temperature::isr!
   static void adc_start(const pin_t pin);
 
   // Is the ADC ready for reading?

Marlin/src/HAL/TEENSY31_32/HAL.h

   // Called by Temperature::init for each sensor at startup
   static void adc_enable(const pin_t ch) {}
 
-  // Begin ADC sampling on the given channel
+  // Begin ADC sampling on the given channel. Called from Temperature::isr!
   static void adc_start(const pin_t ch);
 
   // Is the ADC ready for reading?

Marlin/src/HAL/TEENSY35_36/HAL.h

   // Called by Temperature::init for each sensor at startup
   static void adc_enable(const pin_t) {}
 
-  // Begin ADC sampling on the given channel
+  // Begin ADC sampling on the given pin. Called from Temperature::isr!
   static void adc_start(const pin_t pin);
 
   // Is the ADC ready for reading?

Marlin/src/HAL/TEENSY40_41/HAL.h

   // Called by Temperature::init for each sensor at startup
   static void adc_enable(const pin_t pin) {}
 
-  // Begin ADC sampling on the given channel
+  // Begin ADC sampling on the given pin. Called from Temperature::isr!
   static void adc_start(const pin_t pin);
 
   // Is the ADC ready for reading?

Marlin/src/lcd/e3v2/marlinui/ui_status_480x272.cpp

     #else
       #define HOTEND_STATS 1
     #endif
-    static celsius_t old_temp[HOTEND_STATS] = ARRAY_N_1(HOTEND_STATS, 500),
-                   old_target[HOTEND_STATS] = ARRAY_N_1(HOTEND_STATS, 500);
-    static bool old_on[HOTEND_STATS] = ARRAY_N_1(HOTEND_STATS, false);
+    static celsius_t old_temp[HOTEND_STATS] = { 0 },
+                   old_target[HOTEND_STATS] = { 0 };
+    static bool old_on[HOTEND_STATS] = { false };
   #endif
 
   #if HAS_HEATED_BED
-    static celsius_t old_bed_temp = 500, old_bed_target = 500;
+    static celsius_t old_bed_temp = 0, old_bed_target = 0;
     static bool old_bed_on = false;
     #if HAS_LEVELING
       static bool old_leveling_on = false;