TM4C1294NCPDT: TMC4C1294 master and TM4C123 SPI slave with notification interrupts back to master

Hi,

Robert Starr said:

Should my INT notifcation handler post to a Swi and then use a global mutex or semaphore between the swi and other tasks making spi calls?

Your idea is worth trying. Will you consider disabling other tasks when the master is accessing the slave? The interrupt should have higher priority over other tasks so preemption should not happen in the first place. Using a queue to queue up all the data before sending to the slave is also possible. Not sure if my ideas are worth trying though. 

Hi Charles, thanks for the reply. I'll try having my Hwi post to a Swi. Best I recall, the Swi should have higher priority over tasks, but lower than the Hwi posting to it. I've created my own driver layer similar to other drivers in TI-RTOS.  I create a Gate Mutex in the handle construct, then all the SMPTE_Read(), SMPTE_Write() functions in my driver layer are protected by this mutex. My idea was to have the Hwi INT handler post to a Swi, that in turn makes the SPI call (using the same Mutex wrapped by the object handle) to reads the async data from the SPI slave. The act of reading the slave INT data will reset it's "interrupt" internal logic state. 

Currently I'm using a mailbox to pass data between the Hwi and a SPI reader task, but I considered using the queue_elem constructs and mechanisms initially for this. Maybe I should change my driver to use a sempahore, rather than gate mutex, for all the synchronization. Then the slave read/write functions could then have a timeout in case something fails internally and gets confused with the Swi accessing the SPI stream as well.

I need to go back and read the documentation on Swi's again, and first make sure the default SPI lib layer calls are valid within a Swi context. My current implementation calls Mailbox_post() from the Hwi handler, so I would think the Swi can do the same as tto handle the Hwi calls.

Regards,

Bob

MPTE_Handle SMPTE_construct(SMPTE_Object *obj, SMPTE_Params *params)
{
/* Initialize the object's fields */
obj->spiHandle = params->spiHandle;
obj->gpioCS = params->gpioCS;

GateMutex_construct(&(obj->gate), NULL);

return (SMPTE_Handle)obj;
}

SMPTE_Handle SMPTE_create(SMPTE_Params *params)
{
SMPTE_Handle handle;
Error_Block eb;

Error_init(&eb);

handle = Memory_alloc(NULL, sizeof(SMPTE_Object), NULL, &eb);

if (handle == NULL)
return NULL;

handle = SMPTE_construct(handle, params);

return handle;
}