[FAQ] TDA4VM: Getting Shmoo plots for OSPI PHY tuning

Shmoo plots are basically a set of scatter plots of passing Rx_DLL and Tx_DLL values for a given read delay window.

Please refer to the APP note in the link below get an understanding of the tuning algorithm.
PHY_Tuning_App_Note

1) Define the following Macros in nor_spi_phy_tune.c

#define NOR_log UART_printf

#define SHMOO_TX_DLL_START      (0U)
#define SHMOO_TX_DLL_END        (128U)
#define SHMOO_RX_DLL_START      (0U)
#define SHMOO_RX_DLL_END        (128U)
#define SHMOO_RD_DELAY_START    (0U)
#define SHMOO_RD_DELAY_END      (4U)

2) Add the following API in nor_spi_phy_tune.c

static void NOR_spiPhyFindShmoo(OSPI_Handle handle, uint32_t offset)
{
    OSPI_v0_HwAttrs const        *hwAttrs= (OSPI_v0_HwAttrs const *)handle->hwAttrs;
    int32_t shmooTxDLL, shmooRxDLL, shmooRdDelay, status;
    NOR_log("RD_Delay,\tTxDLL,\tRxDLL\n");
    for(shmooRdDelay = SHMOO_RD_DELAY_START ; shmooRdDelay < SHMOO_RD_DELAY_END ; shmooRdDelay++)
    {
        NOR_spiRdDelayConfig(handle, shmooRdDelay);
        for(shmooTxDLL = SHMOO_TX_DLL_START ; shmooTxDLL < SHMOO_TX_DLL_END ; shmooTxDLL+=4)
        {
            for(shmooRxDLL = SHMOO_RX_DLL_START ; shmooRxDLL < SHMOO_RX_DLL_END ; shmooRxDLL+=4)
            {
                NOR_spiTxRxDllConfig(handle,shmooTxDLL,shmooRxDLL);
                status = NOR_spiPhyRdAttack(hwAttrs->dataAddr + offset);
                if(status == NOR_PASS)
                {
                    NOR_log("%d,\t%d,\t%d\n", shmooRdDelay, shmooTxDLL, shmooRxDLL);
                }
            }
        }
    }
}

3) Call this API from Nor_spiPhyDdrTune or Nor_spiPhySdrTune based on the mode you are using.

RD_Delay,       TxDLL,  RxDLL
2,      24,     0
2,      24,     4
2,      24,     8
2,      24,     12

…

…

…

2,      124,    68
2,      124,    72
2,      124,    76
2,      124,    80
2,      124,    84

You may get this data for more than one read delay.

Copy the data for each ready delay in excel and generate a scatter plot for Tx_DLL vs Rx_DLL, with Tx_DLL on x-asix. Please see the image for reference.

Regards,
Parth