[remote_transmitter] Fix repeat gap timing on LibreTiny Beken (#18585)

Co-authored-by: J. Nick Koston <nick@koston.org>

esphome/components/remote_transmitter/remote_transmitter.cpp

@@ -81,10 +81,14 @@ void RemoteTransmitterComponent::send_internal(uint32_t send_times, uint32_t sen
   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;
   this->transmit_trigger_.trigger();
   for (uint32_t i = 0; i < send_times; i++) {
+    {
       InterruptLock lock;
+      // Re-anchor every iteration: timing must never span a lock boundary, as micros() can
+      // jump when interrupts are re-enabled between repeats (e.g. LibreTiny's Beken micros()
+      // discards its interrupt-lock correction, stretching the repeat gap by the lock duration)
+      this->target_time_ = 0;
       for (int32_t item : this->temp_.get_data()) {
         if (item > 0) {
           const auto length = uint32_t(item);
@@ -97,9 +101,17 @@ void RemoteTransmitterComponent::send_internal(uint32_t send_times, uint32_t sen
       }
       this->await_target_time_();  // wait for duration of last pulse
       this->pin_->digital_write(false);
+    }
 
-    if (i + 1 < send_times)
-      this->target_time_ += send_wait;
+    if (i + 1 < send_times) {
+      // Wait out the repeat gap with interrupts enabled: wait_time is unbounded user config
+      // (previously this spin ran inside the next iteration's lock, disabling interrupts for
+      // the whole gap). Anchoring after the lock release keeps it exact on all platforms.
+      const uint32_t gap_end = micros() + send_wait;
+      while ((int32_t) (gap_end - micros()) > 0) {
+        App.feed_wdt();
+      }
+    }
   }
   this->complete_trigger_.trigger();
 }

esphome/components/remote_transmitter/remote_transmitter.h

@@ -72,7 +72,7 @@ class RemoteTransmitterComponent final : public remote_base::RemoteTransmitterBa
   void space_(uint32_t usec);
 
   void await_target_time_();
-  uint32_t target_time_;
+  uint32_t target_time_{0};
 #endif
 
 #if defined(USE_ESP32) && SOC_RMT_SUPPORTED

tests/components/remote_transmitter/test.bk72xx-ard.yaml

@@ -0,0 +1,7 @@
+remote_transmitter:
+  id: xmitr
+  pin: GPIO26
+  carrier_duty_percent: 50%
+
+packages:
+  buttons: !include common-buttons.yaml