Loss of PWM signal equals to 1500uSec

src/pwm.c

@@ -1,20 +1,33 @@
 #include "servo.h"
 
-volatile uint pwm_in_slice_num;
 volatile uint16_t pwm_count;
 
-uint motor_pwm_slice_num;
-uint motor_a_channel;
-uint motor_b_channel;
+static volatile uint pwm_in_slice_num;
+static volatile bool pwm_in_check_lost = true;
+static repeating_timer_t timer;
+
+static uint motor_pwm_slice_num;
+static uint motor_a_channel;
+static uint motor_b_channel;
+
 
 void pwm_fall_handler() {
  pwm_count = pwm_get_counter(pwm_in_slice_num);
  pwm_set_counter(pwm_in_slice_num, 0);
+ pwm_in_check_lost = false;
 }
 
 void pwm_irq_handler() {
  pwm_clear_irq(pwm_in_slice_num);
- pwm_count = 0;
+ pwm_count = DEFAULT_PWM;
+}
+
+bool check_pwm_callback(__unused struct repeating_timer * param) {
+ if(pwm_in_check_lost) {
+ pwm_count = DEFAULT_PWM;
+ }
+ pwm_in_check_lost = true;
+ return true;// keep repeating
 }
 
 static inline void init_pwm_out() {
@@ -56,6 +69,9 @@ static inline void init_pwm_in() {
  irq_set_enabled(PWM_IRQ_WRAP, true);
  gpio_set_irq_enabled_with_callback(PWM_IN_PIN, GPIO_IRQ_EDGE_FALL, true, pwm_fall_handler);
  pwm_set_enabled(pwm_in_slice_num, true);
+
+ add_repeating_timer_us(60000, check_pwm_callback, NULL, &timer);
+
 }
 
 void init_pwm() {

src/servo.h

@@ -11,6 +11,7 @@
 #include "hardware/i2c.h"
 #include "hardware/structs/clocks.h"
 #include "hardware/clocks.h"
+#include "hardware/timer.h"
 
 #define PWM_IN_PIN (21)
 
@@ -22,6 +23,8 @@
 #define MOTOR_A_PIN (16)
 #define MOTOR_B_PIN (17)
 
+#define DEFAULT_PWM (1500)
+
 extern volatile uint16_t pwm_count;
 
 void init_pwm(void);