Is there anybody working with a ARM9 from Atmel? If I write a small c-file (only with a while(1) loop - no variable or anything else), load it into the controller and start debugging - then I could see some strange things in the memory window.
Above the stack_top definition from the startup code there seems to be a 0xFF pattern (32x 8Bit long) and after that I see some nice tangle of all kind of numbers.
What's the reason for that?? Where are the values from?
saoirse
Unused memory will generally contain undefined values!
But these values are always the same values and I know a few ucontroller who have not undefined values / or these undefined values are 0x00.
Some RAM memory technologies may default to a specific value, i.e. a DRAM memory may start with empty capacitors, representing all zero or all one.
A SRAM cell is basically a flip-flop which means that tolerances will make it flip to zero or one.
When using a high-level language, the startup code supplied with the compiler may already have cleared all configured memory before you get to the user-supplied application entry point.
thanks for the clear answer, Per. How does the part in the startup code look like clearing the internal SRAM to 0x00?