From abf3708cc2b80f69d061800e7aa6c85293440499 Mon Sep 17 00:00:00 2001
From: Carlos Garcia Saura <CarlosGS@users.noreply.github.com>
Date: Wed, 10 Nov 2021 23:28:45 +0100
Subject: [PATCH] [remote_transmitter] accurate pulse timing for ESP8266
 (#2476)

---
 .../remote_transmitter/remote_transmitter.h   |  3 +
 .../remote_transmitter_esp8266.cpp            | 78 ++++++++++---------
 2 files changed, 46 insertions(+), 35 deletions(-)

diff --git a/esphome/components/remote_transmitter/remote_transmitter.h b/esphome/components/remote_transmitter/remote_transmitter.h
index 733ac5e50d..a4235e875f 100644
--- a/esphome/components/remote_transmitter/remote_transmitter.h
+++ b/esphome/components/remote_transmitter/remote_transmitter.h
@@ -32,6 +32,9 @@ class RemoteTransmitterComponent : public remote_base::RemoteTransmitterBase,
   void mark_(uint32_t on_time, uint32_t off_time, uint32_t usec);
 
   void space_(uint32_t usec);
+
+  void await_target_time_();
+  uint32_t target_time_;
 #endif
 
 #ifdef USE_ESP32
diff --git a/esphome/components/remote_transmitter/remote_transmitter_esp8266.cpp b/esphome/components/remote_transmitter/remote_transmitter_esp8266.cpp
index 74e62d4e3b..39752cac5b 100644
--- a/esphome/components/remote_transmitter/remote_transmitter_esp8266.cpp
+++ b/esphome/components/remote_transmitter/remote_transmitter_esp8266.cpp
@@ -33,56 +33,64 @@ void RemoteTransmitterComponent::calculate_on_off_time_(uint32_t carrier_frequen
   *off_time_period = period - *on_time_period;
 }
 
+void RemoteTransmitterComponent::await_target_time_() {
+  const uint32_t current_time = micros();
+  if (this->target_time_ == 0)
+    this->target_time_ = current_time;
+  else if (this->target_time_ > current_time)
+    delayMicroseconds(this->target_time_ - current_time);
+}
+
 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);
-    delayMicroseconds(usec);
-    this->pin_->digital_write(false);
-    return;
-  }
-
-  const uint32_t start_time = micros();
-  uint32_t current_time = start_time;
-
-  while (current_time - start_time < usec) {
-    const uint32_t elapsed = current_time - start_time;
-    this->pin_->digital_write(true);
-
-    delayMicroseconds(std::min(on_time, usec - elapsed));
-    this->pin_->digital_write(false);
-    if (elapsed + on_time >= usec)
-      return;
-
-    delayMicroseconds(std::min(usec - elapsed - on_time, off_time));
-
-    current_time = micros();
+  this->await_target_time_();
+  this->pin_->digital_write(true);
+
+  const uint32_t target = this->target_time_ + usec;
+  if (this->carrier_duty_percent_ < 100 && (on_time > 0 || off_time > 0)) {
+    while (true) {  // Modulate with carrier frequency
+      this->target_time_ += on_time;
+      if (this->target_time_ >= target)
+        break;
+      this->await_target_time_();
+      this->pin_->digital_write(false);
+
+      this->target_time_ += off_time;
+      if (this->target_time_ >= target)
+        break;
+      this->await_target_time_();
+      this->pin_->digital_write(true);
+    }
   }
+  this->target_time_ = target;
 }
+
 void RemoteTransmitterComponent::space_(uint32_t usec) {
+  this->await_target_time_();
   this->pin_->digital_write(false);
-  delayMicroseconds(usec);
+  this->target_time_ += usec;
 }
+
 void RemoteTransmitterComponent::send_internal(uint32_t send_times, uint32_t send_wait) {
   ESP_LOGD(TAG, "Sending remote code...");
   uint32_t on_time, off_time;
   this->calculate_on_off_time_(this->temp_.get_carrier_frequency(), &on_time, &off_time);
+  this->target_time_ = 0;
   for (uint32_t i = 0; i < send_times; i++) {
-    {
-      InterruptLock lock;
-      for (int32_t item : this->temp_.get_data()) {
-        if (item > 0) {
-          const auto length = uint32_t(item);
-          this->mark_(on_time, off_time, length);
-        } else {
-          const auto length = uint32_t(-item);
-          this->space_(length);
-        }
-        App.feed_wdt();
+    for (int32_t item : this->temp_.get_data()) {
+      if (item > 0) {
+        const auto length = uint32_t(item);
+        this->mark_(on_time, off_time, length);
+      } else {
+        const auto length = uint32_t(-item);
+        this->space_(length);
       }
+      App.feed_wdt();
     }
+    this->await_target_time_();  // wait for duration of last pulse
+    this->pin_->digital_write(false);
 
     if (i + 1 < send_times)
-      delayMicroseconds(send_wait);
+      this->target_time_ += send_wait;
   }
 }