RTOS/MSP432-RTOS: Problem with SPI Module

Hi C H,

You’ve looked at the spiloopback example, have you also run it successfully?  

Are you using the MSP432 Launchpad or a custom board?

And have you double checked the wiring of the SPI master port to your SPI module?  Are you able to look at the signals with a logic or bus analyzer to see if there is bus activity?

And what version of TI-RTOS are you using?

If this is still not working, can you post or attach your code so I can look at it?

Thanks,
Scott

Hi Scott, thanks for your answer.

I haven't tested the spiloopback example, might as well test it.

I am working with the MSP432 Launchpad, and with RTOS version 2.16.0.08.

I checked the wiring previously by using a non-RTOS model of my program using driverlib. In this model, I communicate perfectly with the module, but not with the RTOS program.

I can watch the SPI signal on a scope if I use a low transfer speed (eg, 2MHz), this test works on the driverlib program, but not with the RTOS version, meaning the board doesn't send the data, instead of sending it but not capturing the response.

Here's my .c code, in case you need it, in this test program I'm trying to read the value of a register of the module, the SPI parameters and transfer structs are declared inside a custom library I made ("SPIlibRTOS.h"), but the configuration takes place in the main function. Also the ReadReg function of the task is also located in this library. The function loads the parameters of the "ReadReg" command and the direction of the register in the TX buffer wich will be sent to the module in a 8 bit window, and calls the SPI_transfer function. The CE and CS pins are GPIO's which I have included in the pin matrix of the MSP432 file and checked they work:

#include <stdio.h>
#include <xdc/std.h>
#include <xdc/runtime/System.h>
#include <xdc/cfg/global.h>

/* BIOS Header files */
#include <ti/sysbios/BIOS.h>
#include <ti/sysbios/knl/Task.h>

/* TI-RTOS Header files */
#include <ti/drivers/GPIO.h>
#include <ti/sysbios/knl/Swi.h>
#include <ti/drivers/SPI.h>
#include <ti/sysbios/knl/Semaphore.h>

/* Board Header file */
#include "Board.h"

#include "SPIlibRTOS.h"//Custom library, the SPI params and transfer structs are declared here


void isr_pushbutton(UArg arg0){//ISR function for BUTTON1, will call the SWI, which will call the SPIReadtest task
	Swi_post(swi0);
	GPIO_clearInt(Board_BUTTON1);
}


Void SPIReadtest(UArg arg0, UArg arg1){
		Semaphore_pend(semaph,2000); //Take the semaphore, wait a max of 2 ms as timeout
		System_printf("Intiating test\n");
		System_flush();
		uint8_t result = ReadReg(REG0); //Reading the value of the register (1 byte length)
		System_printf("The value of the register is: %ld",result);
		System_flush();
		Semaphore_post(semaph); //Give the semaphore.

}




/*
 *  ======== main ========
 */
int main(void)
{
    //Task_Params taskParams;

    /* Call board init functions */
    Board_initGeneral();
    Board_initGPIO();
    Board_initSPI();

    SPI_Params_init(&SPIparams); //SPI configuration, Master mode, blocking mode, 2MHz clock, 8 bit window per transfer
    SPIparams.transferMode = SPI_MODE_BLOCKING;
    SPIparams.transferCallbackFxn = NULL;
    SPIparams.mode = SPI_MASTER;
    SPIparams.bitRate = 2000000;
    SPIparams.dataSize = 8;
    SPIparams.frameFormat = SPI_POL0_PHA0;

    SPI_MODULE = SPI_open(Board_SPI0, &SPIparams);

    SPItransaction.count = 2; //Transaction configuration, linking of the buffers and make a 2 window transaction, this number may change depending of the function.
    SPItransaction.txBuf = (Ptr)SPITxBuf; 
    SPItransaction.rxBuf = (Ptr)SPIRxBuf;

    GPIO_setCallback(Board_BUTTON1, isr_pushbutton);
    GPIO_enableInt(Board_BUTTON1); //Setting Interrupt for BUTTON 1
    GPIO_write(CSPIN, 1); //Put the CS and CE pins of the SPI module on high
    GPIO_write(CEPIN, 1);
    printf("General init finished \n");
    System_flush();
    Semaphore_post(semaph); //Gives the semaphore, so the task can start after the BIOS started
    /* Start BIOS */
    BIOS_start();
    return (0);
}

Thanks

C

Hello Scott.

What you suggest about the semaphore beign posted through the ISR seems better than my version, I'll test it and see what happens.

And yes, it was intentional to execute the task ony once, since it is a test code to see if the Launchpad and the module communicate together.

Now that you say the SPI functions aren't meant to work on a SWI level, I think I know where my mistake is: For what I understood, I called the Task from the SWI configuration on the cfg so the chain continues (HWI -> SWI -> Task), but that's where the error is, since I'll be calling the SWI function to execute (in a SWI context), instead of going directly to the Task as I though. I'll get rid of the SWI, since I don't really need it, and just use the HWI and the task itself. I'll fix the code and add the changes to the semaphore and see if that's where my mistake was.

Here's the cfg file anyway, in case you can find more mistakes. In this case, I'm using the GPIO callback function as a HWI, since I understand that the function executes in the context of an interruption, maybe that's something I need to change for an HWI instance.

Thanks for the help so far.

C

Edit: I managed to solve the problem and communicate with the module. The error was in using the task as the function the SWI calls when activated, since the function is executed in a SWI context instead of a task context, in which the SPI functions won't work. Thank you for your help.

Edit2: Now that I'm capable of using the SPI module, I'm having a weird problem: Sometimes the bus gives me the correct value of the register, but sometimes it shifts the result of the first byte by n bits to the left (beign n mostly 1 bit, but sometimes 2 and even 3) and nullifies the other bits of the Rx vector, I double checked the wiring and reduced the bus speed, but it keeps happening. I'm using the correct clock phase and polarization, which is proven by the correct transfers. Do you know why is this happening?

1348.empty.cfg