From 3f94e6dcbbec9d3b6c9e8f83308c605b19216b4c Mon Sep 17 00:00:00 2001
From: tomaszduda23 <tomaszduda23@gmail.com>
Date: Mon, 6 Jul 2026 01:52:39 +0200
Subject: [PATCH] [nrf52] let user select libc version (#17408)

---
 esphome/components/nrf52/__init__.py            | 13 +++++++++++++
 esphome/components/zephyr/__init__.py           |  2 --
 tests/components/nrf52/test.nrf52-xiao-ble.yaml |  2 ++
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/esphome/components/nrf52/__init__.py b/esphome/components/nrf52/__init__.py
index a5f2018d551..661fc0758e4 100644
--- a/esphome/components/nrf52/__init__.py
+++ b/esphome/components/nrf52/__init__.py
@@ -200,6 +200,7 @@ DeviceFirmwareUpdate = nrf52_ns.class_("DeviceFirmwareUpdate", cg.Component)
 
 CONF_DFU = "dfu"
 CONF_DCDC = "dcdc"
+CONF_LIBC_NANO = "libc_nano"
 CONF_REG0 = "reg0"
 CONF_UICR_ERASE = "uicr_erase"
 
@@ -248,6 +249,7 @@ CONFIG_SCHEMA = cv.All(
             ): cv.Schema(
                 {
                     cv.Optional(CONF_VERSION): cv.string_strict,
+                    cv.Optional(CONF_LIBC_NANO, default=True): cv.boolean,
                     cv.Optional(CONF_ADVANCED, default={}): cv.Schema(
                         {
                             cv.Optional(
@@ -273,6 +275,7 @@ def _validate_mcumgr(config):
 
 
 def _final_validate(config):
+
     if CONF_DFU in config:
         _validate_mcumgr(config)
     if config[KEY_BOOTLOADER] == BOOTLOADER_ADAFRUIT:
@@ -283,6 +286,13 @@ def _final_validate(config):
     conf = config[CONF_FRAMEWORK]
     advanced = conf[CONF_ADVANCED]
 
+    if conf[CONF_LIBC_NANO] and "logger" in CORE.loaded_integrations:
+        _LOGGER.warning(
+            "Logger is enabled with newlib-nano (libc_nano: true). Some format specifiers "
+            "such as %%zu are not supported and will print incorrectly. "
+            "Set 'libc_nano: false' under 'framework:' to use the full newlib."
+        )
+
     if advanced[CONF_ENABLE_OTA_ROLLBACK]:
         # "disabled: false" means safe mode *is* enabled.
         safe_mode_config = full_config.get(CONF_SAFE_MODE, {CONF_DISABLED: True})
@@ -379,6 +389,9 @@ async def to_code(config: ConfigType) -> None:
     # Enable OTA rollback support
     if advanced[CONF_ENABLE_OTA_ROLLBACK]:
         cg.add_define("USE_OTA_ROLLBACK")
+    zephyr_add_prj_conf("NEWLIB_LIBC", True)
+    zephyr_add_prj_conf("NEWLIB_LIBC_FLOAT_PRINTF", True)
+    zephyr_add_prj_conf("NEWLIB_LIBC_NANO", conf[CONF_LIBC_NANO])
     # c++ support
     if framework_ver < cv.Version(2, 9, 2):
         zephyr_add_prj_conf("CPLUSPLUS", True)
diff --git a/esphome/components/zephyr/__init__.py b/esphome/components/zephyr/__init__.py
index d6c45a744c9..b98f94d37ae 100644
--- a/esphome/components/zephyr/__init__.py
+++ b/esphome/components/zephyr/__init__.py
@@ -134,9 +134,7 @@ def zephyr_to_code(config: ConfigType) -> None:
     cg.add_define("USE_NATIVE_64BIT_TIME")
     cg.set_cpp_standard("gnu++20")
     # c++ support
-    zephyr_add_prj_conf("NEWLIB_LIBC", True)
     zephyr_add_prj_conf("FPU", True)
-    zephyr_add_prj_conf("NEWLIB_LIBC_FLOAT_PRINTF", True)
     zephyr_add_prj_conf("STD_CPP20", True)
     # random_bytes() uses sys_rand_get() which requires the entropy subsystem
     zephyr_add_prj_conf("ENTROPY_GENERATOR", True)
diff --git a/tests/components/nrf52/test.nrf52-xiao-ble.yaml b/tests/components/nrf52/test.nrf52-xiao-ble.yaml
index de4c0c6e00f..e1b5f088bb8 100644
--- a/tests/components/nrf52/test.nrf52-xiao-ble.yaml
+++ b/tests/components/nrf52/test.nrf52-xiao-ble.yaml
@@ -2,3 +2,5 @@ nrf52:
   dfu: true
   reg0:
     voltage: 1.8V
+  framework:
+    libc_nano: false