Remove "delay_microseconds_accurate()" and improve systemwide delayMicroseconds() (#2497)

esphome/components/aht10/aht10.cpp

@@ -73,7 +73,7 @@ void AHT10Component::update() {
   bool success = false;
   for (int i = 0; i < AHT10_ATTEMPTS; ++i) {
     ESP_LOGVV(TAG, "Attempt %d at %6u", i, millis());
-    delay_microseconds_accurate(4);
+    delayMicroseconds(4);
 
     uint8_t reg = 0;
     if (this->write(&reg, 1) != i2c::ERROR_OK) {

esphome/components/esp32/core.cpp

@@ -21,11 +21,7 @@ void IRAM_ATTR HOT yield() { vPortYield(); }
 uint32_t IRAM_ATTR HOT millis() { return (uint32_t)(esp_timer_get_time() / 1000ULL); }
 void IRAM_ATTR HOT delay(uint32_t ms) { vTaskDelay(ms / portTICK_PERIOD_MS); }
 uint32_t IRAM_ATTR HOT micros() { return (uint32_t) esp_timer_get_time(); }
-void IRAM_ATTR HOT delayMicroseconds(uint32_t us) {
-  auto start = (uint64_t) esp_timer_get_time();
-  while (((uint64_t) esp_timer_get_time()) - start < us)
-    ;
-}
+void IRAM_ATTR HOT delayMicroseconds(uint32_t us) { delay_microseconds_safe(us); }
 void arch_restart() {
   esp_restart();
   // restart() doesn't always end execution

esphome/components/esp8266/core.cpp

@@ -12,7 +12,7 @@ void IRAM_ATTR HOT yield() { ::yield(); }
 uint32_t IRAM_ATTR HOT millis() { return ::millis(); }
 void IRAM_ATTR HOT delay(uint32_t ms) { ::delay(ms); }
 uint32_t IRAM_ATTR HOT micros() { return ::micros(); }
-void IRAM_ATTR HOT delayMicroseconds(uint32_t us) { ::delayMicroseconds(us); }
+void IRAM_ATTR HOT delayMicroseconds(uint32_t us) { delay_microseconds_safe(us); }
 void arch_restart() {
   ESP.restart();  // NOLINT(readability-static-accessed-through-instance)
   // restart() doesn't always end execution

esphome/components/remote_transmitter/remote_transmitter_esp32.cpp

@@ -121,10 +121,8 @@ void RemoteTransmitterComponent::send_internal(uint32_t send_times, uint32_t sen
     } else {
       this->status_clear_warning();
     }
-    if (i + 1 < send_times) {
-      delay(send_wait / 1000UL);
-      delayMicroseconds(send_wait % 1000UL);
-    }
+    if (i + 1 < send_times)
+      delayMicroseconds(send_wait);
   }
 }
 

esphome/components/remote_transmitter/remote_transmitter_esp8266.cpp

@@ -36,7 +36,7 @@ void RemoteTransmitterComponent::calculate_on_off_time_(uint32_t carrier_frequen
 void RemoteTransmitterComponent::mark_(uint32_t on_time, uint32_t off_time, uint32_t usec) {
   if (this->carrier_duty_percent_ == 100 || (on_time == 0 && off_time == 0)) {
     this->pin_->digital_write(true);
-    delay_microseconds_accurate(usec);
+    delayMicroseconds(usec);
     this->pin_->digital_write(false);
     return;
   }
@@ -48,19 +48,19 @@ void RemoteTransmitterComponent::mark_(uint32_t on_time, uint32_t off_time, uint
     const uint32_t elapsed = current_time - start_time;
     this->pin_->digital_write(true);
 
-    delay_microseconds_accurate(std::min(on_time, usec - elapsed));
+    delayMicroseconds(std::min(on_time, usec - elapsed));
     this->pin_->digital_write(false);
     if (elapsed + on_time >= usec)
       return;
 
-    delay_microseconds_accurate(std::min(usec - elapsed - on_time, off_time));
+    delayMicroseconds(std::min(usec - elapsed - on_time, off_time));
 
     current_time = micros();
   }
 }
 void RemoteTransmitterComponent::space_(uint32_t usec) {
   this->pin_->digital_write(false);
-  delay_microseconds_accurate(usec);
+  delayMicroseconds(usec);
 }
 void RemoteTransmitterComponent::send_internal(uint32_t send_times, uint32_t send_wait) {
   ESP_LOGD(TAG, "Sending remote code...");
@@ -81,9 +81,8 @@ void RemoteTransmitterComponent::send_internal(uint32_t send_times, uint32_t sen
       }
     }
 
-    if (i + 1 < send_times) {
-      delay_microseconds_accurate(send_wait);
-    }
+    if (i + 1 < send_times)
+      delayMicroseconds(send_wait);
   }
 }
 

esphome/components/sdp3x/sdp3x.cpp

@@ -1,5 +1,6 @@
 #include "sdp3x.h"
 #include "esphome/core/log.h"
+#include "esphome/core/hal.h"
 #include "esphome/core/helpers.h"
 
 namespace esphome {
@@ -25,7 +26,7 @@ void SDP3XComponent::setup() {
     ESP_LOGW(TAG, "Soft Reset SDP3X failed!");  // This sometimes fails for no good reason
   }
 
-  delay_microseconds_accurate(20000);
+  delayMicroseconds(20000);
 
   if (this->write(SDP3X_READ_ID1, 2) != i2c::ERROR_OK) {
     ESP_LOGE(TAG, "Read ID1 SDP3X failed!");

esphome/core/helpers.cpp

@@ -209,17 +209,18 @@ uint8_t crc8(uint8_t *data, uint8_t len) {
   return crc;
 }
 
-void delay_microseconds_accurate(uint32_t usec) {
-  if (usec == 0)
-    return;
-  if (usec < 5000UL) {
-    delayMicroseconds(usec);
-    return;
-  }
-  uint32_t start = micros();
-  while (micros() - start < usec) {
-    delay(0);
+void delay_microseconds_safe(uint32_t us) {  // avoids CPU locks that could trigger WDT or affect WiFi/BT stability
+  auto start = micros();
+  const uint32_t lag = 5000;  // microseconds, specifies the maximum time for a CPU busy-loop.
+                              // it must be larger than the worst-case duration of a delay(1) call (hardware tasks)
+                              // 5ms is conservative, it could be reduced when exact BT/WiFi stack delays are known
+  if (us > lag) {
+    delay((us - lag) / 1000UL);  // note: in disabled-interrupt contexts delay() won't actually sleep
+    while (micros() - start < us - lag)
+      delay(1);  // in those cases, this loop allows to yield for BT/WiFi stack tasks
   }
+  while (micros() - start < us)  // fine delay the remaining usecs
+    ;
 }
 
 uint8_t reverse_bits_8(uint8_t x) {

esphome/core/helpers.h

@@ -255,7 +255,7 @@ struct is_callable  // NOLINT
   static constexpr auto value = decltype(test<T>(nullptr))::value;  // NOLINT
 };
 
-void delay_microseconds_accurate(uint32_t usec);
+void delay_microseconds_safe(uint32_t us);
 
 template<typename T> class Deduplicator {
  public: