SK-AM64B: MCSPI Chip Select when slave runs polled mode.

Hi,

Tobias said:

As far as I can tell, everything is still working when I disconnect CS

Are you trying to operate the MCSPI as a Slave and there is an external Controller? Or as a Controller and there is another external slave?

Regards,

Vaibhav

I'm operating MCSPI as a single slave. An external controller sends data and when it sends it pulls CS. I was excepting it to break when i unplugged CS (just for test) but it continues without any problems. 

Ok, thanks.

The thing i want to know is if "The CS pins to 24 and 12 ( RPI_SPI0_CS0, RPI_SPI0_CS0)" needs to be connected for the example to work. Do the slave actually use the pin when it act as a single slave?

Hi Tobias,

Thanks for your response.

Before we move forward, can you let me know if you see your parameters configured as follows: 

Post your response, I can comment on the chip select part.

Looking forward to your response.

Regards,

Vaibhav

This is the code that gets generated. Note that i don't have a problem that needs to be solved. I just want to know how the driver handles chip select so i don't get a surprise later on.

/*
 * MCSPI
 */
/* MCSPI Driver handles */
MCSPI_Handle gMcspiHandle[CONFIG_MCSPI_NUM_INSTANCES];
/* MCSPI Driver Open Parameters */
MCSPI_OpenParams gMcspiOpenParams[CONFIG_MCSPI_NUM_INSTANCES] =
{
    {
        .transferMode           = MCSPI_TRANSFER_MODE_BLOCKING,
        .transferTimeout        = SystemP_WAIT_FOREVER,
        .transferCallbackFxn    = NULL,
        .msMode                 = MCSPI_MS_MODE_PERIPHERAL,
        .mcspiDmaIndex = -1,
    },
};
/* MCSPI Driver Channel Configurations */
MCSPI_ChConfig gConfigMcspi0ChCfg[CONFIG_MCSPI0_NUM_CH] =
{
    {
        .chNum              = MCSPI_CHANNEL_0,
        .frameFormat        = MCSPI_FF_POL0_PHA1,
        .bitRate            = 50000000,
        .csPolarity         = MCSPI_CS_POL_LOW,
        .trMode             = MCSPI_TR_MODE_TX_RX,
        .inputSelect        = MCSPI_IS_D1,
        .dpe0               = MCSPI_DPE_ENABLE,
        .dpe1               = MCSPI_DPE_DISABLE,
        .slvCsSelect        = MCSPI_SLV_CS_SELECT_0,
        .startBitEnable     = FALSE,
        .startBitPolarity   = MCSPI_SB_POL_LOW,
        .csIdleTime         = MCSPI_TCS0_0_CLK,
        .turboEnable        = FALSE,
        .defaultTxData      = 0x0U,
        .txFifoTrigLvl      = 16U,
        .rxFifoTrigLvl      = 16U,
    },
};

MCSPI_ChConfig *gConfigMcspiChCfg[1] =
{
    gConfigMcspi0ChCfg,
};


MCSPI_DmaChConfig gMcspiDmaChConfig[1] =
{
    NULL,
};

void Drivers_mcspiOpen(void)
{
    uint32_t instCnt;
    int32_t  status = SystemP_SUCCESS;

    for(instCnt = 0U; instCnt < CONFIG_MCSPI_NUM_INSTANCES; instCnt++)
    {
        gMcspiHandle[instCnt] = NULL;   /* Init to NULL so that we can exit gracefully */
    }

    /* Open all instances */
    for(instCnt = 0U; instCnt < CONFIG_MCSPI_NUM_INSTANCES; instCnt++)
    {
        gMcspiHandle[instCnt] = MCSPI_open(instCnt, &gMcspiOpenParams[instCnt]);
        if(NULL == gMcspiHandle[instCnt])
        {
            DebugP_logError("MCSPI open failed for instance %d !!!\r\n", instCnt);
            status = SystemP_FAILURE;
            break;
        }
    }

    if(SystemP_FAILURE == status)
    {
        Drivers_mcspiClose();   /* Exit gracefully */
    }

    return;
}

void Drivers_mcspiClose(void)
{
    uint32_t instCnt;

    /* Close all instances that are open */
    for(instCnt = 0U; instCnt < CONFIG_MCSPI_NUM_INSTANCES; instCnt++)
    {
        if(gMcspiHandle[instCnt] != NULL)
        {
            MCSPI_close(gMcspiHandle[instCnt]);
            gMcspiHandle[instCnt] = NULL;
        }
    }

    return;
}

Hello Tobias,

Allow me sometime to comment on the same.

Regards,

Vaibhav

Hi,

I am looking at an application configured in Peripheral Mode. I am debugging through each of the APIs to understand how Chip Select is controlled.

Allow me sometime to get back to you with the behaviour of the chip select in peripheral mode.

Regards,

Vaibhav