external spi loopback on RM48 USB stick development kit

Andrew,

I agree, I only see that you can use the CS[0] pin for the SPI driver.

You need to do at least two things to make CS[1] used instead.  (There might be something I'm forgetting so I'm saying at least two).

You probably also want to change the other spiREG->PC[x] registers like PC7 and PC8 which set the default pull to pullup...  you might get away without it but not sure.

First, you need to go through the spiInit() function and change the initialization of the spiREGx->PCy registers.

All of these will look something like:

    /** - SPI4 Port output values */
    spiREG4->PC3 =  1U        /* SCS[0U] */
                    | (0U << 8U)  /* ENA */
                    | (0U << 9U)  /* CLK */
                    | (0U << 10U)  /* SIMO */
                    | (0U << 11U); /* SOMI */

And you will change them to something like this:

    /** - SPI4 Port output values */
    spiREG4->PC3 =  2U        /* SCS[1] */
                    | (0U << 8U)  /* ENA */
                    | (0U << 9U)  /* CLK */
                    | (0U << 10U)  /* SIMO */
                    | (0U << 11U); /* SOMI */

In order to use CS[1] instead of CS[0].

You should probably change all of the port control registers.    Just remember that on the slave SPI you want the CS port to be an input not an output...

You can directly edit spiInit() to make the changes, but if you do so then if you generate from HalCoGen again you will need to make the changes again.

So while not pretty, you can go to the end of the spiInit() function where the comment is for user code:

/* USER CODE BEGIN (3) */
/* USER CODE END */
}

And in this section add code that over-writes the generated code for the pin control pins.  This will result in writing to the pins twice which isn't necessary but it will be convenient for you since the code will survive through re-generation.

Second, in the example code example_spi_Master_Slave.c, the chip select is set here:

 dataconfig1_t.CSNR    = 0xFE; (which is 1111 1110 or CS[0] is low)

This is the pattern that you want to appear on the chip select lines when transmitting.

To switch this to use CS[1] instead of CS[0],  change the code to :

 dataconfig1_t.CSNR    = 0xFD;  (which is 1111 1101 or CS[1] is low)

There might be something I missed, but I hope this gets you started.