From 18217fbe101b67261dd4d2256d65a2f4e572aaa7 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Mon, 5 Jan 2026 17:16:47 -1000
Subject: [PATCH] [atc_mithermometer] Reduce heap allocations with stack-based
 string formatting (#12996)

---
 .../components/atc_mithermometer/atc_mithermometer.cpp | 10 ++++++----
 .../components/atc_mithermometer/atc_mithermometer.h   |  2 +-
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/esphome/components/atc_mithermometer/atc_mithermometer.cpp b/esphome/components/atc_mithermometer/atc_mithermometer.cpp
index 9d550fcf8c..b4d2929742 100644
--- a/esphome/components/atc_mithermometer/atc_mithermometer.cpp
+++ b/esphome/components/atc_mithermometer/atc_mithermometer.cpp
@@ -21,7 +21,9 @@ bool ATCMiThermometer::parse_device(const esp32_ble_tracker::ESPBTDevice &device
     ESP_LOGVV(TAG, "parse_device(): unknown MAC address.");
     return false;
   }
-  ESP_LOGVV(TAG, "parse_device(): MAC address %s found.", device.address_str().c_str());
+  char addr_buf[MAC_ADDRESS_PRETTY_BUFFER_SIZE];
+  const char *addr_str = device.address_str_to(addr_buf);
+  ESP_LOGVV(TAG, "parse_device(): MAC address %s found.", addr_str);
 
   bool success = false;
   for (auto &service_data : device.get_service_datas()) {
@@ -32,7 +34,7 @@ bool ATCMiThermometer::parse_device(const esp32_ble_tracker::ESPBTDevice &device
     if (!(parse_message_(service_data.data, *res))) {
       continue;
     }
-    if (!(report_results_(res, device.address_str()))) {
+    if (!(report_results_(res, addr_str))) {
       continue;
     }
     if (res->temperature.has_value() && this->temperature_ != nullptr)
@@ -103,13 +105,13 @@ bool ATCMiThermometer::parse_message_(const std::vector<uint8_t> &message, Parse
   return true;
 }
 
-bool ATCMiThermometer::report_results_(const optional<ParseResult> &result, const std::string &address) {
+bool ATCMiThermometer::report_results_(const optional<ParseResult> &result, const char *address) {
   if (!result.has_value()) {
     ESP_LOGVV(TAG, "report_results(): no results available.");
     return false;
   }
 
-  ESP_LOGD(TAG, "Got ATC MiThermometer (%s):", address.c_str());
+  ESP_LOGD(TAG, "Got ATC MiThermometer (%s):", address);
 
   if (result->temperature.has_value()) {
     ESP_LOGD(TAG, "  Temperature: %.1f °C", *result->temperature);
diff --git a/esphome/components/atc_mithermometer/atc_mithermometer.h b/esphome/components/atc_mithermometer/atc_mithermometer.h
index d22e3f069b..e37b5f4350 100644
--- a/esphome/components/atc_mithermometer/atc_mithermometer.h
+++ b/esphome/components/atc_mithermometer/atc_mithermometer.h
@@ -41,7 +41,7 @@ class ATCMiThermometer : public Component, public esp32_ble_tracker::ESPBTDevice
 
   optional<ParseResult> parse_header_(const esp32_ble_tracker::ServiceData &service_data);
   bool parse_message_(const std::vector<uint8_t> &message, ParseResult &result);
-  bool report_results_(const optional<ParseResult> &result, const std::string &address);
+  bool report_results_(const optional<ParseResult> &result, const char *address);
 };
 
 }  // namespace atc_mithermometer