core: serial: implement Serial.printf()

cores/arduino/zephyrSerial.cpp

@@ -187,6 +187,17 @@ void arduino::ZephyrSerial::flush() {
 	}
 }
 
+#if CONFIG_ARDUINO_SERIAL_PRINTF
+void arduino::ZephyrSerial::printf(const char *fmt, ...) {
+	char message[CONFIG_ARDUINO_SERIAL_PRINTF_BUFFER_SIZE];
+	va_list args;
+	va_start(args, fmt);
+	vsnprintf(message, sizeof(message), fmt, args);
+	va_end(args);
+	this->write((uint8_t *)message, strlen(message));
+}
+#endif
+
 #if (DT_NODE_HAS_PROP(DT_PATH(zephyr_user), cdc_acm))
 #define FIRST_UART_INDEX 1
 #else

cores/arduino/zephyrSerial.h

@@ -89,6 +89,10 @@ class ZephyrSerial : public HardwareSerial {
 	int peek();
 	int read();
 
+#if CONFIG_ARDUINO_SERIAL_PRINTF
+	void printf(const char *fmt, ...);
+#endif
+
 	operator bool() {
 		return true;
 	}

loader/Kconfig

@@ -17,3 +17,16 @@ config MAIN_STACK_REGION
 	depends on CODE_DATA_RELOCATION
 	help
 	  Specify the memory region for main stack.
+
+config ARDUINO_SERIAL_PRINTF
+	bool "Enable Serial.printf()"
+	default n
+	help
+	  Enable the Serial.printf() function.
+
+config ARDUINO_SERIAL_PRINTF_BUFFER_SIZE
+	int "Serial.printf() buffer size"
+	depends on ARDUINO_SERIAL_PRINTF
+	default 128
+	help
+	  Set the buffer size for the Serial.printf() function.

variants/arduino_nano_matter_mgm240sd22vna/arduino_nano_matter_mgm240sd22vna.conf

@@ -35,3 +35,5 @@ CONFIG_STACK_CANARIES=n
 CONFIG_THREAD_ANALYZER=n
 CONFIG_SYS_HEAP_RUNTIME_STATS=n
 # CONFIG_LOG_DEFAULT_LEVEL=3
+
+CONFIG_ARDUINO_SERIAL_PRINTF=y