A non-initialized variable section is the memory region that is not cleared or reassigned upon system power-up or soft reset (such as an OTA upgrade), and contains data that must be preserved after a program restart.

To define and use variables in the non-initialized variable section, three steps are required:

1. In the .cmd file mentioned above, declare the space within SECTIONS in RAM, as shown in the figure.

   .TI.noinit : > SRAM, type = NOINIT

   

2. To place data in a non-initialized variable section, the application must use compiler attributes to declare it and assign it to the .TI.noinit section.

   __attribute__((noinit)) int noinit_global;
   __attribute__((noinit,location(0x100))) int noinit_location_global;
   

   
3. Using this variable in your code to build your program will add the corresponding definition to Memory Allocation.

The code in the figure above is an example. A soft reset occurs every 5 seconds. noinit_global will increment continuously and will not be initialized to 0.

Note that a hardware reset (power cycle/reset pin reset) will reset this variable. If power-down hold is required, use non-volatile (NV) memory.