Safe-Guard-Memory.md

@@ -15,12 +15,12 @@ First of all you have to enable the backup SRAM: the backup domain is not readab
 Moreover, after a reset, the backup domain is protected against possible unwanted write accesses, so you have to disable write protection before being able to write again to the backup region.
 
 The Miosix SGM driver constructor prepares the backup domain for you: it enables the backup clock and disables the write protection. It also retrieves the last board reset reason.  
-Please remember that the backup domain content is wiped by the driver if, after the reset, the `RCC_CSR_SFTRSTF` (i.e. software reset) flag is not set in the `RCC_CSR` register.  
+Please remember that the backup domain content is wiped by the driver if, after the reset, the `RCC_CSR_SFTRSTF` (i.e. software reset) flag is not set in the `RCC->CSR` register.  
   
-> :warning: **WARNING: Notice that more than one flag could be set at the same time in the `RCC_CSR` register!**  
+> :warning: **WARNING: Notice that more than one flag could be set at the same time in the `RCC->CSR` register!**  
 > **(e.g. software reset and reset pin flags)**
   
-After enabling it, in order to read/write from/to the backup domain, you can simply use pointers or standard C/C++ functions, such as `memcpy` (better performance), starting from the backup region base address, which is `BKPSRAM_BASE`.
+After enabling it, in order to read/write from/to the backup domain, you can simply use pointers or standard C/C++ functions, such as `memcpy`, starting from the backup region base address, which is `BKPSRAM_BASE`. Notice that _this is not the preferable way to use the backup SRAM region_.
 
 Otherwise, by specifing a dedicated section in the linker script (see below), you can use the `__attribute__(section(<section-name>))` in order to automatically store a global variable in the backup region. Then, in case of reboot, the variable's content is preserved.  
 The Miosix SGM driver defines the following macro:
@@ -42,6 +42,7 @@ uint8_t myvar __attribute__((section(".preserve__at_0x40024055")));
 ```
 
 ## Example
+<!---
 These basic examples show how you can write to the backup SRAM using the Miosix SGM driver.  
 In a very similar way you can also read the data you stored. 
 
@@ -69,7 +70,10 @@ int main() {
     return 0;
 }
 ```
-#### 2. Section Attribute
+--->
+
+<!---#### 2. Section Attribute--->
+
 If we declare `myvar` using the `PRESERVE` directive, its content will be preserved in the backup SRAM.
 ```cpp
 #include <Common.h>
@@ -83,18 +87,25 @@ uint8_t myvar2 __attribute__((section(".preserve")));
 int main() {
     
     SGM &sgm = SGM::instance();
+    ResetReason reason = SGM::instance().lastResetReason();
 
-    // the TRACE will print "myvar = 5"
-    // after the reboot
-    TRACE("myvar = %u", myvar);
+    Thread::sleep(1000);
 
-    myvar = 5;
+    if (reason == RST_SW)
+    {
+        // the TRACE will print "myvar = 5"
+        // after the reboot
+        TRACE("myvar = %u \n", myvar);
+
+        myvar = 5;
+    }
 
     reboot();
 
     return 0;
 }
 ```
+In the _References_ sections below you can find two more detailed examples of how to get the reboot reset
 
 ## Linker Script
 In the board's linker script, a backup memory region has to be defined:
@@ -148,6 +159,8 @@ Refer to the [Skyward STM32F429ZI Anakin board](https://git.skywarder.eu/scs/mio
 
 * [StackOverflow - How to use backup SRAM as EEPROM in STM32F4](https://stackoverflow.com/questions/20667754/how-to-use-backup-sram-as-eeprom-in-stm32f4)
 
+* Usage Examples : https://pastebin.com/juMtttmj and https://pastebin.com/zipPb1bT
+
 * [Skyward's STM32F429ZI Anakin board](https://git.skywarder.eu/scs/miosix-kernel/-/tree/master/miosix/arch/cortexM4_stm32f4/stm32f429zi_skyward_anakin)
 
 * [RM0090, Reference Manual - STM32F405/415, STM32F407/417, STM32F427/437 and STM32F429/439 advanced Arm-based 32-bit MCUs (mainly sections 2.3.1, 5.1.2, 6.3.20/7.3.20)](https://www.st.com/resource/en/reference_manual/dm00031020-stm32f405-415-stm32f407-417-stm32f427-437-and-stm32f429-439-advanced-arm-based-32-bit-mcus-stmicroelectronics.pdf)