From 26a3ec41d6037f44b4479ee35983aab9f789688f Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Sun, 9 Nov 2025 16:23:33 -0600
Subject: [PATCH] [sx126x] Optimize send_packet action memory usage - store
 static data in flash (#11790)

Co-authored-by: Jesse Hills <3060199+jesserockz@users.noreply.github.com>
---
 esphome/components/sx126x/__init__.py  |  7 ++++--
 esphome/components/sx126x/automation.h | 30 +++++++++++++++-----------
 2 files changed, 23 insertions(+), 14 deletions(-)

diff --git a/esphome/components/sx126x/__init__.py b/esphome/components/sx126x/__init__.py
index 370cd102d4..f8f3b9d104 100644
--- a/esphome/components/sx126x/__init__.py
+++ b/esphome/components/sx126x/__init__.py
@@ -3,7 +3,7 @@ import esphome.codegen as cg
 from esphome.components import spi
 import esphome.config_validation as cv
 from esphome.const import CONF_BUSY_PIN, CONF_DATA, CONF_FREQUENCY, CONF_ID
-from esphome.core import TimePeriod
+from esphome.core import ID, TimePeriod
 
 MULTI_CONF = True
 CODEOWNERS = ["@swoboda1337"]
@@ -329,5 +329,8 @@ async def send_packet_action_to_code(config, action_id, template_arg, args):
         templ = await cg.templatable(data, args, cg.std_vector.template(cg.uint8))
         cg.add(var.set_data_template(templ))
     else:
-        cg.add(var.set_data_static(data))
+        # Generate static array in flash to avoid RAM copy
+        arr_id = ID(f"{action_id}_data", is_declaration=True, type=cg.uint8)
+        arr = cg.static_const_array(arr_id, cg.ArrayInitializer(*data))
+        cg.add(var.set_data_static(arr, len(data)))
     return var
diff --git a/esphome/components/sx126x/automation.h b/esphome/components/sx126x/automation.h
index 6b2371e253..2282c583cb 100644
--- a/esphome/components/sx126x/automation.h
+++ b/esphome/components/sx126x/automation.h
@@ -14,28 +14,34 @@ template<typename... Ts> class RunImageCalAction : public Action<Ts...>, public
 
 template<typename... Ts> class SendPacketAction : public Action<Ts...>, public Parented<SX126x> {
  public:
-  void set_data_template(std::function<std::vector<uint8_t>(Ts...)> func) {
-    this->data_func_ = func;
-    this->static_ = false;
+  void set_data_template(std::vector<uint8_t> (*func)(Ts...)) {
+    this->data_.func = func;
+    this->len_ = -1;  // Sentinel value indicates template mode
   }
 
-  void set_data_static(const std::vector<uint8_t> &data) {
-    this->data_static_ = data;
-    this->static_ = true;
+  void set_data_static(const uint8_t *data, size_t len) {
+    this->data_.data = data;
+    this->len_ = len;  // Length >= 0 indicates static mode
   }
 
   void play(const Ts &...x) override {
-    if (this->static_) {
-      this->parent_->transmit_packet(this->data_static_);
+    std::vector<uint8_t> data;
+    if (this->len_ >= 0) {
+      // Static mode: copy from flash to vector
+      data.assign(this->data_.data, this->data_.data + this->len_);
     } else {
-      this->parent_->transmit_packet(this->data_func_(x...));
+      // Template mode: call function
+      data = this->data_.func(x...);
     }
+    this->parent_->transmit_packet(data);
   }
 
  protected:
-  bool static_{false};
-  std::function<std::vector<uint8_t>(Ts...)> data_func_{};
-  std::vector<uint8_t> data_static_{};
+  ssize_t len_{-1};  // -1 = template mode, >=0 = static mode with length
+  union Data {
+    std::vector<uint8_t> (*func)(Ts...);  // Function pointer (stateless lambdas)
+    const uint8_t *data;                  // Pointer to static data in flash
+  } data_;
 };
 
 template<typename... Ts> class SetModeTxAction : public Action<Ts...>, public Parented<SX126x> {