RTOS/MSP432E401Y: SDRAM as Default Heap

Hi Mike,

TI-RTOS creates a "system" heap by default. Again by default, it is a HeapMem instance (variable size first fit heap). It also creates the malloc (and free, etc.) function that sits on top of the system heap.

The easiest thing to do would be to create the SDRAM memory segment in the linker (I just grabbed an open memory range) and then direct the .priheap section to that segment. 

MEMORY
{
    FLASH (RX)  : origin = 0x00000000, length = 0x00100000
    SRAM (RWX)  : origin = 0x20000000, length = 0x00040000
    SDRAM (RWX) : origin = 0x10000000, length = 0x00040000
}

...

/* Heap buffer used by HeapMem */
    .priheap   : {
        __primary_heap_start__ = .;
        . += HEAPSIZE;
        __primary_heap_end__ = .;
    } > SDRAM align 8

Of course you can adjust the HEAPSIZE in the linker file also. When I built an application with the above linker file, I see this in the mapfile

.priheap   0    10000000    00020000     UNINITIALIZED
                  10000000    00020000     --HOLE--

HeapMem uses __primary_heap_start__ and __primary_heap_end__ to know the location of the heap (and initialize it accordingly during startup before main()). Here is the code in the .cfg to do this.

var HeapMem = xdc.useModule('ti.sysbios.heaps.HeapMem');
HeapMem.primaryHeapBaseAddr = "&__primary_heap_start__";
HeapMem.primaryHeapEndAddr = "&__primary_heap_end__";

var heapMemParams = new HeapMem.Params();
heapMemParams.usePrimaryHeap = true;
Program.global.heap0 = HeapMem.create(heapMemParams);

Memory.defaultHeapInstance = Program.global.heap0;

Todd

Sorry, I missed the task stack part....

In the linker file, create a subsection (e.g. .bss:myStacks) that is in SDRAM

    .data   :   > SRAM
    .bss:myStacks : > SDRAM
    .bss    :   > SRAM

Then in the .cfg, if you want all the statically created tasks to be placed there, add the following

Task.defaultStackSection = ".bss:myStacks";

Note: you can individually control each task stack placement also if you want finer granularity via the stackSection parameter. In the app I built, only the idle task was statically created. Here is the mapfile

.bss:myStacks 
*          0    10020000    00000200     UNINITIALIZED
                  10020000    00000200     mutex_pem4f.oem4f (.bss:myStacks)

For runtime created (or constructed) tasks, if you supply the stack in the params structure, you can place it via #pragma or via the linker file. If you don't supply a stack, the create will allocate it for you. By default, it will use the System heap. You can supply a Heap_Handle in the stackHeap parameter in the create though if you want it from a different heap. Also in the .cfg, you can specify the default heap to use for allocating stacks (via the Task.defaultStackHeap setting).

Todd

I Have the SDRAM initialization figured out, .cfg file needed:

var Startup = xdc.useModule('xdc.runtime.Startup');
Startup.resetFxn = "&epi_init"; //my epi startup function