Allocated data section on flash for active image number

Author: bbogush

firmware/bootloader/main.c

@@ -11,7 +11,10 @@
 /* Flash layout
  * ------------ 0x08000000
  * |bootloader |
- * | 16K       |
+ * |14K        |
+ * -------------0x08003800
+ * |data       |
+ * |2K         |
  * ------------ 0x08004000
  * |image1     |   
  * |120K       |
@@ -26,27 +29,50 @@
 #define VERSION "\r\nBootloader ver: " MAKE_STR(SW_VERSION_MAJOR) "." \
     MAKE_STR(SW_VERSION_MINOR) "." MAKE_STR(SW_VERSION_BUILD) "\r\n"
 
-#define APP_ADDRESS_OFFSET 0x4000
-#define APP_ADDRESS (FLASH_BASE + APP_ADDRESS_OFFSET)
+#define APP1_ADDRESS_OFFSET 0x4000
+#define APP1_ADDRESS (FLASH_BASE + APP1_ADDRESS_OFFSET)
+#define APP2_ADDRESS_OFFSET 0x22000
+#define APP2_ADDRESS (FLASH_BASE + APP2_ADDRESS_OFFSET)
 
 typedef void (*app_func_t)(void);
+typedef struct __attribute__((__packed__))
+{
+    uint8_t active_image;
+} config_t;
+
+__attribute__((__section__(".user_data"))) const char data[1];
 
 int main()
 {
     app_func_t app;
-    uint32_t jump_addr;
+    uint32_t jump_addr, vt_offset, sp_addr;
+    config_t *config = (config_t *)data;
 
     uart_init();
     print(VERSION);
 
+    print("Start application: ");
+    if (!config->active_image)
+    {
+        print("0\r\n");
+        vt_offset = APP1_ADDRESS_OFFSET;
+        jump_addr = *(__IO uint32_t *)(APP1_ADDRESS + 4);
+        sp_addr = *(__IO uint32_t *)APP1_ADDRESS;
+    }
+    else
+    {
+        print("1\r\n");
+        vt_offset = APP2_ADDRESS_OFFSET;
+        jump_addr = *(__IO uint32_t *)(APP2_ADDRESS + 4);
+        sp_addr = *(__IO uint32_t *)APP2_ADDRESS;
+    }
+
     /* Relocate vector table */
-    NVIC_SetVectorTable(NVIC_VectTab_FLASH, APP_ADDRESS_OFFSET);
-    /* Set application address */
-    jump_addr = *(__IO uint32_t *)(APP_ADDRESS + 4);
-    app = (app_func_t)jump_addr;
+    NVIC_SetVectorTable(NVIC_VectTab_FLASH, vt_offset);
     /* Initialize application's Stack Pointer */
-    __set_MSP(*(__IO uint32_t *)APP_ADDRESS);
+    __set_MSP(sp_addr);
     /* Start application */
+    app = (app_func_t)jump_addr;
     app();
 
     return 0;

firmware/bootloader/stm32_flash.ld

@@ -15,7 +15,8 @@ _estack = 0x2000c000;
 
 MEMORY
 {
-    FLASH(rx) : ORIGIN = 0x08000000, LENGTH = 16K
+    FLASH(rx) : ORIGIN = 0x08000000, LENGTH = 14K
+    DATA(rw) : ORIGIN = 0x08003800, LENGTH = 2K
     RAM(xrw) : ORIGIN = 0x20000000, LENGTH = 48K
 }
 
@@ -89,6 +90,13 @@ SECTIONS
         PROVIDE_HIDDEN(__fini_array_end = .);
     } > FLASH
 
+    .user_data :
+    {
+        . = ALIGN(4);
+        KEEP(*(.user_data))
+        . = ALIGN(4);
+    } > DATA
+
     /* Used by startup code to initialize data */
     _sidata = .;