spi_xfer byte order in multi-byte commands / responses?

[aefelgate]

Hello,

I am using the CCS compiler's built-in spi_xfer() function to transmit 16 bit and 24 bit commands to a device.

What is the BYTE order required? Can anybody answer this simple question?

e.g. I wish to transfer the following bytes, in the following order:

0x01 0x00 0x00

I create a 32-bit variable, and us it as follows:

#use spi(MASTER,
DI=PIN_A3,
DO=PIN_A5,
CLK=PIN_A2,
ENABLE=PIN_C0,
ENABLE_ACTIVE=0,
MODE=3,
BITS=32,
LSB_FIRST,
STREAM=SPI_STREAM)

int32 spi_data = 5;
int32 spi_xfer_status = 0;

// Send 0x05 0x00 0x00
spi_xfer_status = spi_xfer(SPI_STREAM, spi_data, 24);

Is this correct? Or, does it need to be 0x05000000?
Or 0x00050000

I am sending data LSB FIRST, but what is the byte order???

Also, I am assumin the response, spi_xfer_status in my code above, will be returned with the byte order mapped in the same way as the command?

The CCS compiler manual and examples only give a single byte example when using the spi_xfer() command; there needs to be a multi-byte example, which would then easily clear up this confusion.

[PCM programmer]

You can find answer from the .LST file, after compiling your test program:

Here, the LSB (5) is put into address 0x21:

[aefelgate]

Thanks for clearing this up. Now that I understand how the compiler orders the bits and bytes I know that is not the problem.