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TMS320F280025: UART and SPI

Hung Kai Woo1
Intellectual 825 points
Part Number: TMS320F280025
Other Parts Discussed in Thread: AFE031

Hi

My project uses SCI A to RS485. Below is my code for configuration

code [1]

            SCI_setConfig(SCIA_BASE, 25000000, ulBaudRate, (wlen |
                                                         stopbits |
                                                         parity));

            SCI_resetChannels(SCIA_BASE);
            SCI_clearInterruptStatus(SCIA_BASE, SCI_INT_TXRDY | SCI_INT_RXRDY_BRKDT);
            SCI_enableModule(SCIA_BASE);
            SCI_performSoftwareReset(SCIA_BASE);

            SCI_enableInterrupt(SCIA_BASE, SCI_INT_TXRDY | SCI_INT_RXRDY_BRKDT);

            SCI_clearInterruptStatus(SCIA_BASE, SCI_INT_TXRDY | SCI_INT_RXRDY_BRKDT);

            Interrupt_enable(INT_SCIA_RX);
            Interrupt_enable(INT_SCIA_TX);

The setup works very well and then I add SPI module B to control TI AFE031 code [2]

Add SPI Module for  communication  between the IC and MCU. Below is code to configure SPI B

code [2]


    GPIO_SetupPinMux(16, GPIO_MUX_CPU1, 0);
    GPIO_SetupPinOptions(16, GPIO_OUTPUT, GPIO_PUSHPULL)
    GPIO_WritePin(16, 0);

    SpibRegs.SPIFFTX.all = HAL_SPI_FFTX;
    SpibRegs.SPIFFRX.all = HAL_SPI_FFRX;
    SpibRegs.SPIFFCT.all = 0x0;

        EALLOW;
    ClkCfgRegs.LOSPCP.all = HAL_SPI_LSPCLK;
    EDIS;

    SpibRegs.SPICCR.bit.SPISWRESET = 0;
    SpibRegs.SPICCR.bit.CLKPOLARITY = 1;
    SpibRegs.SPICCR.bit.SPILBK = 0;
    SpibRegs.SPICCR.bit.SPICHAR = 15; //16-bit character
    SpibRegs.SPICCR.bit.HS_MODE = 0x1;
    SpibRegs.SPICTL.bit.SPIINTENA = 0; // Interrupt disable
    SpibRegs.SPICTL.bit.TALK = 1; // Transmit enable
    SpibRegs.SPICTL.bit.MASTER_SLAVE = 1; //Master
    SpibRegs.SPICTL.bit.CLK_PHASE = 0; //Normal phase, depending on SPICCR.6 (CLOCK_POLARITY)
    SpibRegs.SPICTL.bit.OVERRUNINTENA = 0; //Overrun interrupt disable

    SpibRegs.SPIBRR.bit.SPI_BIT_RATE = HAL_SPI_BRR;

    SpibRegs.SPIPRI.bit.FREE = 1;  // Set so breakpoints don't disturb xmission

    SpibRegs.SPICCR.bit.SPISWRESET = 1; // Ready to transmit

UART Module A (SCI) doesn't aftere code [2] executed. If Code [2] doesn't executed, UART function recovered.

I am using SCI A for UART and SPI B separately for different function. I supposed they should not be affected each other.

Any idea?

  • 0
    TI__Mastermind 19795 points

    Hi,

    Thanks for your question! If I understand your question correctly, when SPIB is added, SCIA stops working, is this correct?

    If so then the likely causes it that the SPIB interrupts (TX and RX) are likely "starving" the SCIA interrupt. By "starving" I mean that the SCI interrupts ISRs are not getting a chance to enter because they are being preempted constantly by SPIB interrupts. This is because SPIB has higher priority that SCIA (see PIE Channel Mapping table from TRM):

    Depending on use-case for SPI and SCI, the best solution is to make SPI use the DMA to automatically transfer data to the memory WITHOUT interrupting. This will allow SCI (which does not have DMA) to continue having its interrupts fire.

    Another potential solution is to stop SPI communications (both TX and RX) for long enough to allow SCI to get a chance to communicate as well.

    One more potential solution you can try (that is not very good) is to occasionally temporarily disable SPI interrupts.For example, every 10 SPI interrupts, you disable the interrupt on exit, and let the SCIA ISR re-enable SPI. This can be dangerous though if SCI is not always transmitting. A better way to implement would be with timer interrupts that occasionally read out the data from the SCI and SPI buffers, thereby removing need for actual SCI and SPI interrupts.

    Let me know if any questions on this.

    Regards,

    Vince

  • 0 in reply to Vince
    Intellectual 825 points

    Hi Vince

    Thanks for your information. I am using polling in SPI, no interrupt.

    SCI A uses GPIO 2 and 3 for Tx/RX. Using below code to mux the pin

        GPIO_SetupPinMux(2, GPIO_MUX_CPU1, 9);
        GPIO_SetupPinMux(3, GPIO_MUX_CPU1, 9);

    SPI B uses below code for mux

        GPIO_SetupPinOptions(7, GPIO_INPUT, GPIO_ASYNC | GPIO_PULLUP);
        // SPI_MISO
        GPIO_SetupPinOptions(6, GPIO_INPUT, GPIO_ASYNC | GPIO_PULLUP);
        // SPI_CS
        GPIO_SetupPinOptions(29, GPIO_INPUT, GPIO_ASYNC | GPIO_PULLUP);
        // SPI_CLK
        GPIO_SetupPinOptions(28, GPIO_INPUT, GPIO_ASYNC | GPIO_PULLUP);

    // Set PinMux to SPIB module : HK Woo
    //
        GPIO_SetupPinMux(6, GPIO_MUX_CPU1, 7);
        GPIO_SetupPinMux(7, GPIO_MUX_CPU1, 7);
        GPIO_SetupPinMux(29, GPIO_MUX_CPU1, 11);
        GPIO_SetupPinMux(28, GPIO_MUX_CPU1, 11);

    BR

    HK

  • 0 in reply to Hung Kai Woo1
    TI__Mastermind 19795 points

    Hi,

    Thanks for the follow-up. Can you verify if UART works when this line is left out of the SPI init code?
      ClkCfgRegs.LOSPCP.all = HAL_SPI_LSPCLK;

    It's possible changing the LSPCLK is changing the effective baud rate, and causing an issue. This shouldn't prevent transmission, but can prevent reception (RX).

    Regards,

    Vince

  • 0 in reply to Vince
    Intellectual 825 points

    Will try it and let you know the result.