⚡️ PWM for ESP32 I2S expander (#24193)

Marlin/src/HAL/ESP32/HAL.h

@@ -68,6 +68,9 @@
 #define PWM_RESOLUTION   10u   // Default PWM bit resolution
 #define CHANNEL_MAX_NUM  15u   // max PWM channel # to allocate (7 to only use low speed, 15 to use low & high)
 #define MAX_PWM_IOPIN    33u   // hardware pwm pins < 34
+#ifndef MAX_EXPANDER_BITS
+  #define MAX_EXPANDER_BITS 32 // I2S expander bit width (max 32)
+#endif
 
 // ------------------------
 // Types
@@ -76,6 +79,12 @@
 typedef double isr_float_t;   // FPU ops are used for single-precision, so use double for ISRs.
 typedef int16_t pin_t;
 
+typedef struct pwm_pin {
+  uint32_t pwm_cycle_ticks = 1000000UL / (PWM_FREQUENCY) / 4; // # ticks per pwm cycle
+  uint32_t pwm_tick_count = 0;  // current tick count
+  uint32_t pwm_duty_ticks = 0;  // # of ticks for current duty cycle
+} pwm_pin_t;
+
 class Servo;
 typedef Servo hal_servo_t;
 
@@ -197,6 +206,8 @@ public:
   // Free SRAM
   static int freeMemory();
 
+  static pwm_pin_t pwm_pin_data[MAX_EXPANDER_BITS];
+
   //
   // ADC Methods
   //