CCS/AM6548: AM65x IDK SPI receiver problem

Tool/software: Code Composer Studio

Hello Everybody!

I would like to connect something to an SPI port of IDK.

I can send but can not receive.

I have found J20 connector where signals of MCSPI1 port are available.

spiInitCfg driver table has 5 entries:

I have hacked the table by copying index 2 to index 3 and set the base address to MCSPI1 to reach that port:

    SPI_v1_HWAttrs spi_cfg;

    SPI_socGetInitCfg(2, &spi_cfg);
    spi_cfg.baseAddr = CSL_MCSPI1_CFG_BASE;
    SPI_socSetInitCfg(3, &spi_cfg);

And here is the initialization of SPI port:

    SPI_init();

    /* SPI initialization */
    SPI_socGetInitCfg(instance, &config);

    /* configuration example master see:
     * ti/pdk_am65xx_1_0_7/packages/ti/drv/spi/example/mcspi_slavemode */
    config.enableIntr = false;
    config.chNum = 0U;

    SPI_socSetInitCfg(instance, &config);
    /* Initialize SPI handle */
    SPI_Params_init(&params);
    params.transferMode = SPI_MODE_BLOCKING;
    params.transferCallbackFxn = NULL;
    params.transferTimeout = SemaphoreP_WAIT_FOREVER;
    params.bitRate = 12000000U;

    handle = SPI_open(instance, &params);

And then I sent data using Index 3 and could see CLK, CS and MOSI signals on pins of J20 connector by scope.

I used bool SPI_transfer(SPI_Handle handle, SPI_Transaction *spiTrans) fuction

Till now it is still OK.

Then I wanted to test the SPI input too, therefore I connected MISO input to MOSI output with a jumper (J20/2 – J20/1) and expected that the transfer function gets back the sent data.

    uint32_t loopCtr = 0;
    uint32_t readbackValue = 0x55555555U;
    while (true)
    {
        loopCtr++;
        ret = spi.transmit((uint8_t *)&loopCtr, (uint8_t *)&readbackValue, sizeof(loopCtr));
        if ( loopCtr == readbackValue ) {
            gpio.reset(USER_LED1);
            gpio.toggle(USER_LED0);
        }
        else {
            gpio.reset(USER_LED0);
            gpio.toggle(USER_LED1);
        }
        Task_sleep(20); /* suspend task*/
    }

(spi.transmit function calls SPI_transfer of course)

And here is my problem: I got 0 in readbackValue instead of the sent value always.

Connection to J20/2 pin is OK, I could see MOSI signal on it when changed DPE1 & DPE0 bits of MCSPI_CHCONF_1 register from 0b10 to 0b01 (or 0b00)

I suppose that input selector (IS) bit of MCSPI_CHCONF_1 can be used for internal loopback.

Here are my results 

 OK means that MOSI signal was seen on that pin by scope.

- means inactivity, i.e. low level on that pin.

And I have never get back good value.

Memory browser window was active during my debug session becasue I watched / changed the SPI registers there.

Debugger may disturb operation when it reads registers unexpectedly (to update the browser window) therefore I have turned it off and repeated the SPI transfer,  but got the same 0 result.

Register content from memory bowser @ 0x02110100

MCSPI1_CFG_MCSPI_REVISION
0000002B    00000000    00000000    00000000
MCSPI1_CFG_MCSPI_SYSCONFIG
00000308
MCSPI1_CFG_MCSPI_SYSSTATUS
00000001
MCSPI1_CFG_MCSPI_IRQSTATUS
00020001
MCSPI1_CFG_MCSPI_IRQENABLE
00000000
MCSPI1_CFG_MCSPI_WAKEUPENABLE
00000000
MCSPI1_CFG_MCSPI_SYST
00000000
MCSPI1_CFG_MCSPI_MODULCTRL
00000001
MCSPI1_CFG_MCSPI_CHCONF_0
180603C8
MCSPI1_CFG_MCSPI_CHSTAT_0
0000002E
MCSPI1_CFG_MCSPI_CHCTRL_0
00000000
MCSPI1_CFG_MCSPI_TX_0
00000000
MCSPI1_CFG_MCSPI_RX_0
00000000

What is wrong here? Howe can I receive on SPI?

Best regards

Kalman