From 266e4ae91fb2414528163109e708af6246b57952 Mon Sep 17 00:00:00 2001
From: Keith Burzinski <kbx81x@gmail.com>
Date: Mon, 3 Nov 2025 17:30:37 -0600
Subject: [PATCH] [helpers] Add `get_mac_address_into_buffer()` (#11700)

---
 esphome/core/helpers.cpp | 6 ++++++
 esphome/core/helpers.h   | 5 +++++
 2 files changed, 11 insertions(+)

diff --git a/esphome/core/helpers.cpp b/esphome/core/helpers.cpp
index fb8b220b2f..568acb9f1b 100644
--- a/esphome/core/helpers.cpp
+++ b/esphome/core/helpers.cpp
@@ -643,6 +643,12 @@ std::string get_mac_address_pretty() {
   return format_mac_address_pretty(mac);
 }
 
+void get_mac_address_into_buffer(std::span<char, 13> buf) {
+  uint8_t mac[6];
+  get_mac_address_raw(mac);
+  format_mac_addr_lower_no_sep(mac, buf.data());
+}
+
 #ifndef USE_ESP32
 bool has_custom_mac_address() { return false; }
 #endif
diff --git a/esphome/core/helpers.h b/esphome/core/helpers.h
index cf21ddc16d..91ddc70afa 100644
--- a/esphome/core/helpers.h
+++ b/esphome/core/helpers.h
@@ -8,6 +8,7 @@
 #include <iterator>
 #include <limits>
 #include <memory>
+#include <span>
 #include <string>
 #include <type_traits>
 #include <vector>
@@ -1027,6 +1028,10 @@ std::string get_mac_address();
 /// Get the device MAC address as a string, in colon-separated uppercase hex notation.
 std::string get_mac_address_pretty();
 
+/// Get the device MAC address into the given buffer, in lowercase hex notation.
+/// Assumes buffer length is 13 (12 digits for hexadecimal representation followed by null terminator).
+void get_mac_address_into_buffer(std::span<char, 13> buf);
+
 #ifdef USE_ESP32
 /// Set the MAC address to use from the provided byte array (6 bytes).
 void set_mac_address(uint8_t *mac);