[remote_transmitter] Use hardware PWM on rtl87xx to fix watchdog crash (#18579)

esphome/components/remote_transmitter/__init__.py

@@ -185,12 +185,14 @@ FILTER_SOURCE_FILES = filter_source_files_from_platform(
             PlatformFramework.ESP32_ARDUINO,
             PlatformFramework.ESP32_IDF,
         },
+        "remote_transmitter_rtl87xx.cpp": {
+            PlatformFramework.RTL87XX_ARDUINO,
+        },
         "remote_transmitter.cpp": {
             PlatformFramework.ESP32_ARDUINO,
             PlatformFramework.ESP32_IDF,
             PlatformFramework.ESP8266_ARDUINO,
             PlatformFramework.BK72XX_ARDUINO,
-            PlatformFramework.RTL87XX_ARDUINO,
             PlatformFramework.LN882X_ARDUINO,
             PlatformFramework.RP2_ARDUINO,
         },

esphome/components/remote_transmitter/remote_transmitter.cpp

@@ -2,7 +2,8 @@
 #include "esphome/core/log.h"
 #include "esphome/core/application.h"
 
-#if defined(USE_LIBRETINY) || defined(USE_ESP8266) || defined(USE_RP2) || (defined(USE_ESP32) && !SOC_RMT_SUPPORTED)
+#if (defined(USE_LIBRETINY) && !defined(USE_RTL87XX)) || defined(USE_ESP8266) || defined(USE_RP2) || \
+    (defined(USE_ESP32) && !SOC_RMT_SUPPORTED)
 
 namespace esphome::remote_transmitter {
 

esphome/components/remote_transmitter/remote_transmitter.h

@@ -65,14 +65,21 @@ class RemoteTransmitterComponent final : public remote_base::RemoteTransmitterBa
  protected:
   void send_internal(uint32_t send_times, uint32_t send_wait) override;
 #if defined(USE_ESP8266) || defined(USE_LIBRETINY) || defined(USE_RP2) || (defined(USE_ESP32) && !SOC_RMT_SUPPORTED)
+  void await_target_time_();
+  uint32_t target_time_{0};
+#endif
+#if defined(USE_ESP8266) || (defined(USE_LIBRETINY) && !defined(USE_RTL87XX)) || defined(USE_RP2) || \
+    (defined(USE_ESP32) && !SOC_RMT_SUPPORTED)
   void calculate_on_off_time_(uint32_t carrier_frequency, uint32_t *on_time_period, uint32_t *off_time_period);
 
   void mark_(uint32_t on_time, uint32_t off_time, uint32_t usec);
 
   void space_(uint32_t usec);
-
+#endif
-  void await_target_time_();
+#ifdef USE_RTL87XX
-  uint32_t target_time_{0};
+  // Carrier frequency the PWM is currently configured for; 0 = not yet configured
+  uint32_t current_carrier_frequency_{0};
+  void *pwm_{nullptr};  // pwmout_t*, opaque here to keep the SDK header out of this shared header
 #endif
 
 #if defined(USE_ESP32) && SOC_RMT_SUPPORTED

esphome/components/remote_transmitter/remote_transmitter_rtl87xx.cpp

@@ -0,0 +1,137 @@
+#include "remote_transmitter.h"
+#include "esphome/core/application.h"
+#include "esphome/core/log.h"
+
+// clang-tidy cannot parse the Realtek SDK headers pulled in via ArduinoPrivate.h
+#if defined(USE_RTL87XX) && !defined(CLANG_TIDY)
+
+// ArduinoPrivate.h = Arduino.h + the SDK's mbed HAL (pwmout etc.) with the core's fixes for
+// type-name collisions between the two (e.g. PinMode)
+#include <ArduinoPrivate.h>
+#include <FreeRTOS.h>
+#include <task.h>
+
+namespace esphome::remote_transmitter {
+
+static const char *const TAG = "remote_transmitter";
+
+// The carrier is generated by the PWM peripheral instead of bit-banging the pin: software carrier
+// generation requires disabling interrupts for the whole frame, but this core's micros() is derived
+// from the FreeRTOS tick and freezes while interrupts are off, so the timing loop never advances and
+// the watchdog resets the chip. With hardware PWM, software only times the mark/space envelope and
+// interrupts can stay enabled.
+//
+// The PWM is driven through the SDK's pwmout HAL directly rather than the Arduino wiring layer:
+// changing the carrier frequency via the wiring requires a GPIO/PWM pin mode round-trip, which
+// use-after-frees the core's per-pin state (pinRemoveMode() frees without nulling) and corrupts the
+// heap. pwmout_period_us() changes the frequency with no mode transitions.
+
+void RemoteTransmitterComponent::setup() {
+  // Deliberately no pin_->setup(): registering the pin as GPIO claims it in the SDK's pin
+  // management, and the pad is then never handed over to the PWM peripheral -- pwmout_init()
+  // must own the pin from the start.
+  PinInfo *info = pinInfo(this->pin_->get_pin());
+  if (info == nullptr || !pinSupported(info, PIN_PWM)) {
+    // checked here because the AmebaZ (RTL8710B) SDK does not report PWM init failure
+    ESP_LOGE(TAG, "Pin %u is not PWM-capable", this->pin_->get_pin());
+    this->mark_failed();
+    return;
+  }
+  auto *pwm = new pwmout_t();
+  this->pwm_ = pwm;
+  pwmout_init(pwm, static_cast<PinName>(info->gpio));
+#if LT_RTL8720C
+  // only the AmebaZ2 SDK's pwmout_s reports init success
+  if (!pwm->is_init) {
+    ESP_LOGE(TAG, "PWM init failed on pin %u", this->pin_->get_pin());
+    delete pwm;
+    this->pwm_ = nullptr;
+    this->mark_failed();
+    return;
+  }
+#endif
+  pwmout_period_us(pwm, 26);  // placeholder; the real carrier period is set per transmission
+  pwmout_write(pwm, this->pin_->is_inverted() ? 1.0f : 0.0f);
+}
+
+void RemoteTransmitterComponent::dump_config() {
+  ESP_LOGCONFIG(TAG,
+                "Remote Transmitter:\n"
+                "  Carrier Duty: %u%%",
+                this->carrier_duty_percent_);
+  LOG_PIN("  Pin: ", this->pin_);
+}
+
+void RemoteTransmitterComponent::await_target_time_() {
+  const uint32_t current_time = micros();
+  if (this->target_time_ == 0) {
+    this->target_time_ = current_time;
+  } else {
+    while ((int32_t) (this->target_time_ - micros()) > 0) {
+    }
+  }
+}
+
+void RemoteTransmitterComponent::digital_write(bool value) {
+  if (this->pwm_ == nullptr)
+    return;
+  pwmout_write(static_cast<pwmout_t *>(this->pwm_), (value != this->pin_->is_inverted()) ? 1.0f : 0.0f);
+}
+
+void RemoteTransmitterComponent::send_internal(uint32_t send_times, uint32_t send_wait) {
+  auto *pwm = static_cast<pwmout_t *>(this->pwm_);
+  if (pwm == nullptr) {
+    ESP_LOGW(TAG, "Cannot send: PWM not initialized");
+    return;
+  }
+  ESP_LOGD(TAG, "Sending remote code");
+  const uint32_t carrier_frequency = this->temp_.get_carrier_frequency();
+  // unmodulated protocols (no carrier or 100% duty) drive the pin constantly during marks
+  float mark_duty =
+      (carrier_frequency > 0 && this->carrier_duty_percent_ < 100) ? this->carrier_duty_percent_ / 100.0f : 1.0f;
+  float space_duty = 0.0f;
+  if (this->pin_->is_inverted()) {
+    mark_duty = 1.0f - mark_duty;
+    space_duty = 1.0f;
+  }
+  if (carrier_frequency > 0 && carrier_frequency != this->current_carrier_frequency_) {
+    // round(1000000/freq), clamped like the bit-bang path so a bad lambda can't hand the SDK a zero period
+    const uint32_t period = std::max(uint32_t(1), (1000000UL + carrier_frequency / 2) / carrier_frequency);
+    pwmout_period_us(pwm, period);
+    this->current_carrier_frequency_ = carrier_frequency;
+  }
+  this->transmit_trigger_.trigger();
+  const UBaseType_t saved_priority = uxTaskPriorityGet(nullptr);
+  for (uint32_t i = 0; i < send_times; i++) {
+    // Boost task priority for the frame only, so WiFi/lwIP tasks can't preempt mid-frame and
+    // merge adjacent marks. Interrupts stay enabled: micros() needs the FreeRTOS tick, and
+    // ISR latency is within receiver tolerance.
+    vTaskPrioritySet(nullptr, configMAX_PRIORITIES - 1);
+    // Re-anchor every iteration: a late exit from the normal-priority gap wait must not
+    // leave the schedule behind micros(), which would compress the next frame's leading items
+    this->target_time_ = 0;
+    for (int32_t item : this->temp_.get_data()) {
+      const bool is_mark = item > 0;
+      this->await_target_time_();
+      pwmout_write(pwm, is_mark ? mark_duty : space_duty);
+      this->target_time_ += is_mark ? uint32_t(item) : uint32_t(-item);
+      App.feed_wdt();
+    }
+    this->await_target_time_();  // wait for duration of last pulse
+    pwmout_write(pwm, space_duty);
+    vTaskPrioritySet(nullptr, saved_priority);
+    if (i + 1 < send_times) {
+      // The repeat gap is user-configurable and unbounded, so wait it out at normal
+      // priority, feeding the watchdog
+      const uint32_t gap_end = micros() + send_wait;
+      while ((int32_t) (gap_end - micros()) > 0) {
+        App.feed_wdt();
+      }
+    }
+  }
+  this->complete_trigger_.trigger();
+}
+
+}  // namespace esphome::remote_transmitter
+
+#endif  // USE_RTL87XX && !CLANG_TIDY

tests/components/remote_transmitter/test.rtl87xx-ard.yaml

@@ -0,0 +1,7 @@
+remote_transmitter:
+  id: xmitr
+  pin: GPIO12
+  carrier_duty_percent: 50%
+
+packages:
+  buttons: !include common-buttons.yaml