Regarding using TWO software SPI

[GAGAN]

Hi, I am using PIC24HJ256GP210A and i want to implement TWO SOFTWARE SPI and TWO HARDWARE SPI.
For HARDWARE SPI in order to write we have SPI_WRITE()-For SPI1 and SPI_WRITE2()- For SPI2 builtin fuction its working fine.
but using software SPI i used #USE SPI() and mention all required pins for DI, DO, CLK .
How to use SPI_XFER() funtion for TWO Sofware SPI ? What is the argument i need to provide in spi_xfer() funtion to differentiate between TWO software SPI ??

[Ttelmah]

Honestly use spi_xfer for all of the SPI's.

spi_write and spi_read, are the 'old' CCS way of handling SPI's.

Basically with #use spi, you set up a hardware SPI with:

[GAGAN]

Thank you for your reply
and can it be possible to send 32 bit data in one transaction like spi_xfer(0xFFFF,software_SPI1,32) ?
So what argument should i follow to set #use spi, Setup_SPI() and spi_xfer() function?? to send 32 bit data in one transaction?

[GAGAN]

and What is the significance of SETUP_SPI(options) ? In which case i should use ?? Do i have to make use of #USE SPI () or SETUP_SPI() in order to setup my SPI??

[Ttelmah]

If you read the manual, you will find that the stuff is 'linked'.

So if you look at setup_spi, it cross links to spi_read and spi_write.
If you look at #use spi, it links to spi_xfer. They do not link to the other way of working.

You do not mix and match. They are two separate ways of handling spi. So #use, with spi_xfer, _or_, setup, with read & write.
If you use '#USE', you do not use setup_spi, spi_read or spi_write.

Now to use 32bit transfers, you have to set the maximum transfer length in the #use at 32bits (it defaults to this if you don't have a bits= setting). Then you need to specify the length in your transfers. So to send a single byte:

spi_xfer(STREAM_NAME, value_to_send, 8);

sends/receives an 8bit value, while

spi_xfer(STREAM_NAME, value_to_send, 16);

sends/receives 16bits, and

spi_xfer(STREAM_NAME, value_to_send, 32);

sends/receives 32bits.

Setup, read and write, were the 'old' way of handling spi. Only supported hardware, and relatively limited functionality. The #use capability was added five or more years ago (mid V4 compilers), with the stream names, and the ability to do software or hardware handling (like #USE RS232). Problem is that a lot of the examples are 'old' and show the older system, and people will try to mix the two methods (which can give problems...).

[GAGAN]

thanks for your Suggestion,,,

[GAGAN]

Hi,
I am trying to transfer 32 data in one transaction so i mentioned #use spi(MASTER, SPI1, BAUD=10000, BITS=32, Stream=HW_SPI1, MODE=0) and using this function to transfer spi_xfer(HW_SPI1, 0X00120357, 32);
but when i check the output in scope after every 8 bit transfer its generating some delay.
Please let me know how to adjust this delay after between every 8 bit transfer?
Also please let me know what parameter i should take care in order to get all the 32 bit data without generating delay in between after each 8 bit is transferred.

[Ttelmah]

There is going to be some, but it should be tiny.

Remember the hardware only supports 8bit transmissions, so the code has to wait for the status flag to say 'register is empty', and only then load the next byte.

However should only be a handful of instruction times. Doesn't matter, since as SPI is synchronous, the clock will stop, and the slave will wait for the next bit.

[GAGAN]

Thank you for your feedback,,,
1-How do I set the baud rate in #use spi ( ) so that I can run my spi @ a clock rate of <50 MHz ?
2-by using software spi, when I check my output the data is delayed by almost one spi clock pulse, so in this case my last data is outputted after the end of last clock, as I am trying to transfer 32 bit data in one transaction.
Could you please provide the information about the factor affecting this issue?

[temtronic]

Helpful hint:
While your project is open, press F11. The CCS manual will 'magically' appear ! You can minimize it, so it's always easy to access.

Look for the pre processor directives, locate use spi, click on it, on the right side of the screen 'how to use' it appears.....

Jay

[Ttelmah]

and, as already said, having pauses in the data/clock, doesn't matter at all. That is the whole point of synchronous transactions.