RTOS/TM4C1294NCPDT: SPI1: How to setup callback to operate via SWI

Hi Richard,

 We don't have any specific examples for SPI using SWI. I think you might have already tried the TI-RTOS SPI example which is using TASK , not SWI. For SWI usage you can refer to the section 3.5 Software Interrupt in the TI-RTOS Kernel user's guide for details. 

 It is not clear to me what you meant that the SPI stops working after a while.  Did the SWI still get called after you think the SPI stops working? Try to place a breakpoint in your SPI function to see if it is getting called.

 I'm not a TI-RTOS expert but I don't think it is necessary to disable the SWI if you can setup the correct priority such that your RFD_DAC12Update_SWI_Fxn will not be preempted by other SWIs. Same can be done for the HWI.

 Looking at your code, it does not seem that you are using the TI-RTOS provides drivers for SPI but rather you are using the TivaWare drivers for SPI. Is this correct? From a high level I don't see an issue with your usage of the Swi_post() within the HWI ISR. Below is an example code of using the SWI which is similar to what you have.

//----------------------------------------
// BIOS header files
//----------------------------------------
#include <xdc/std.h>  						//mandatory - have to include first, for BIOS types
#include <ti/sysbios/BIOS.h> 				//mandatory - if you call APIs like BIOS_start()
#include <xdc/runtime/Log.h>				//needed for any Log_info() call
#include <xdc/cfg/global.h> 				//header file for statically defined objects/handles
#include <xdc/runtime/System.h>
#include <xdc/runtime/Error.h>
#include <ti/sysbios/hal/Hwi.h>


//------------------------------------------
// TivaWare Header Files
//------------------------------------------
#include <stdint.h>
#include <stdbool.h>

#include "inc/hw_types.h"
#include "inc/hw_memmap.h"
#include "driverlib/sysctl.h"
#include "driverlib/gpio.h"
#include "inc/hw_ints.h"
#include "driverlib/interrupt.h"
#include "driverlib/timer.h"


//----------------------------------------
// Prototypes
//----------------------------------------
void hardware_init(void);
void ledToggle(void);
void Timer_ISR(void);


//---------------------------------------
// Globals
//---------------------------------------
volatile int16_t i16ToggleCount = 0;


//---------------------------------------------------------------------------
// main()
//---------------------------------------------------------------------------
void main(void)
{
    Hwi_Params hwiParams;
    Hwi_Handle myHwi;
    Error_Block eb;
    /* Initialize error block and hwiParams to default values */
    Error_init(&eb);
    Hwi_Params_init(&hwiParams);
    hwiParams.enableInt = FALSE;
    /* Create Hwi on vector 51 which is the TIMER3A */
    myHwi = Hwi_create(51, (Hwi_FuncPtr)Timer_ISR, &hwiParams, &eb);
    if (myHwi == NULL) {
    System_abort("Hwi create failed");
    }
    Hwi_enableInterrupt(51);


    Swi_Params swiParams;
     Swi_Handle LEDSwi;
     Error_Block eb2;
     /* Initialize error block and hwiParams to default values */
     Error_init(&eb2);
     Swi_Params_init(&swiParams);
     LEDSwi = Swi_create((Swi_FuncPtr)ledToggle, &swiParams, &eb2);
     if (LEDSwi == NULL) {
     System_abort("Swi create failed");
     }


   hardware_init();							// init hardware via Xware

   BIOS_start();

}


//---------------------------------------------------------------------------
// hardware_init()
//
// inits GPIO pins for toggling the LED
//---------------------------------------------------------------------------
void hardware_init(void)
{
	uint32_t ui32Period;

	//Set CPU Clock to 40MHz. 400MHz PLL/2 = 200 DIV 5 = 40MHz
	SysCtlClockSet(SYSCTL_SYSDIV_5|SYSCTL_USE_PLL|SYSCTL_XTAL_16MHZ|SYSCTL_OSC_MAIN);

	// ADD Tiva-C GPIO setup - enables port, sets pins 1-3 (RGB) pins for output
	SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOF);
	GPIOPinTypeGPIOOutput(GPIO_PORTF_BASE, GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3);

	// Turn on the LED
	GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3, 4);

	// Timer 2 setup code
	SysCtlPeripheralEnable(SYSCTL_PERIPH_TIMER3);			// enable Timer 3 periph clks
	TimerConfigure(TIMER3_BASE, TIMER_CFG_PERIODIC);		// cfg Timer 3 mode - periodic

	ui32Period = (SysCtlClockGet() /2);						// period = CPU clk div 2 (500ms)
	TimerLoadSet(TIMER3_BASE, TIMER_A, ui32Period);			// set Timer 3 period

	TimerIntEnable(TIMER3_BASE, TIMER_TIMA_TIMEOUT);		// enables Timer 3 to interrupt CPU

	TimerEnable(TIMER3_BASE, TIMER_A);						// enable Timer 3

}


//---------------------------------------------------------------------------
// ledToggle()
//
// toggles LED on Tiva-C LaunchPad
//---------------------------------------------------------------------------
void ledToggle(void)
{
	// LED values - 2=RED, 4=BLUE, 8=GREEN
	if(GPIOPinRead(GPIO_PORTF_BASE, GPIO_PIN_2))
	{
		GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3, 0);
	}
	else
	{
		GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_2, 4);
	}

	i16ToggleCount += 1;									// keep track of #toggles

	Log_info1("LED TOGGLED [%u] TIMES",i16ToggleCount);		// send toggle count to UIA

}


//---------------------------------------------------------------------------
// Timer ISR - called by BIOS Hwi (see app.cfg)
//
// Posts Swi (or later a Semaphore) to toggle the LED
//---------------------------------------------------------------------------
void Timer_ISR(void)
{
    TimerIntClear(TIMER3_BASE, TIMER_TIMA_TIMEOUT);			// must clear timer flag FROM timer

	Swi_post(LEDSwi);										// post LEDSwi
}

 So the problem can be either SPI specific or related to how the SPI is used in the Ti-RTOS context which will need more investigation from your side. Do you have many other HWIs/SWIs going on? What if for debugging purpose, you disable/remove these non SPI SWIs? Will it make a difference?