diff --git a/include/flash.h b/include/flash.h
index 9b225e4..39f9e3d 100644
--- a/include/flash.h
+++ b/include/flash.h
@@ -29,6 +29,7 @@ THE SOFTWARE.
 #include <stdbool.h>
 #include <stdint.h>
 
+void flash_load();
 bool flash_set_user_id(uint8_t channel, uint32_t user_id);
 uint32_t flash_get_user_id(uint8_t channel);
 void flash_flush();
diff --git a/ldscripts/mem.ld b/ldscripts/mem.ld
index 945a948..6711f9c 100644
--- a/ldscripts/mem.ld
+++ b/ldscripts/mem.ld
@@ -14,6 +14,7 @@
 MEMORY
 {
   FLASH (rx) : ORIGIN = 0x08000000, LENGTH = 64K
+  DATA (rwx) : ORIGIN = 0x0801F800, LENGTH = 2K
   RAM (xrw) : ORIGIN = 0x20000000, LENGTH = 16K
 
   /*
diff --git a/ldscripts/sections.ld b/ldscripts/sections.ld
index 9ef139f..24f81c5 100644
--- a/ldscripts/sections.ld
+++ b/ldscripts/sections.ld
@@ -53,6 +53,12 @@ ENTRY(_start)
 
 SECTIONS
 {
+	/* user data flash */
+	.user_data : ALIGN(4)
+	{
+		*(.user_data)
+	} > DATA
+	
     /*
      * For Cortex-M devices, the beginning of the startup code is stored in
      * the .isr_vector section, which goes to FLASH. 
diff --git a/src/flash.c b/src/flash.c
index 965e5fa..7935a70 100644
--- a/src/flash.c
+++ b/src/flash.c
@@ -24,18 +24,35 @@ THE SOFTWARE.
 
 */
 
+
 #include "flash.h"
+#include <string.h>
+#include "stm32f0xx_hal_flash.h"
 
 #define NUM_CHANNEL 1
 
-static struct {
+typedef struct {
 	uint32_t user_id[NUM_CHANNEL];
-} flash_data;
+} flash_data_t;
+
+static flash_data_t flash_data_ram;
+__attribute__((__section__(".user_data"))) const flash_data_t flash_data_rom;
+
+
+void flash_load()
+{
+	memcpy(&flash_data_ram, &flash_data_rom, sizeof(flash_data_t));
+}
 
 bool flash_set_user_id(uint8_t channel, uint32_t user_id)
 {
 	if (channel<NUM_CHANNEL) {
-		flash_data.user_id[channel] = user_id;
+
+		if (flash_data_ram.user_id[channel] != user_id) {
+			flash_data_ram.user_id[channel] = user_id;
+			flash_flush();
+		}
+
 		return true;
 	} else {
 		return false;
@@ -45,7 +62,7 @@ bool flash_set_user_id(uint8_t channel, uint32_t user_id)
 uint32_t flash_get_user_id(uint8_t channel)
 {
 	if (channel<NUM_CHANNEL) {
-		return flash_data.user_id[channel];
+		return flash_data_ram.user_id[channel];
 	} else {
 		return 0;
 	}
@@ -54,4 +71,18 @@ uint32_t flash_get_user_id(uint8_t channel)
 void flash_flush()
 {
 
+	FLASH_EraseInitTypeDef erase_pages;
+	erase_pages.PageAddress = (uint32_t)&flash_data_rom;
+	erase_pages.NbPages = 1;
+	erase_pages.TypeErase = TYPEERASE_PAGES;
+
+	uint32_t error;
+
+	HAL_FLASH_Unlock();
+	__HAL_FLASH_CLEAR_FLAG(FLASH_FLAG_EOP | FLASH_FLAG_WRPERR | FLASH_SR_PGERR);
+	HAL_FLASHEx_Erase(&erase_pages, &error);
+	if (error==0xFFFFFFFF) { // erase finished successfully
+		HAL_FLASH_Program(FLASH_TYPEPROGRAM_WORD, (uint32_t)&flash_data_rom.user_id[0], flash_data_ram.user_id[0]);
+	}
+	HAL_FLASH_Lock();
 }
diff --git a/src/main.c b/src/main.c
index 88a4914..8edaa3f 100644
--- a/src/main.c
+++ b/src/main.c
@@ -40,6 +40,7 @@ THE SOFTWARE.
 #include "led.h"
 #include "dfu.h"
 #include "timer.h"
+#include "flash.h"
 
 void HAL_MspInit(void);
 void SystemClock_Config(void);
@@ -61,6 +62,8 @@ int main(void)
 	HAL_Init();
 	SystemClock_Config();
 
+	flash_load();
+
 	gpio_init();
 
 	led_init(&hLED, LED1_GPIO_Port, LED1_Pin, false, LED2_GPIO_Port, LED2_Pin, false);