C6678 SPI question

Gabriele_Giannini

I have a question about the SPI.

I cannot understand the difference in 2 flags:

SPIFLG->TXINTFLG (indicate if the transmit buffer (TXBUF) is empty and a new data can be written to it)

SPIBUF->TXFULL (indicates if TX shift register is full)

Aren't they saying the same thing?

What of the 2 flag is better to check while i'm trasmitting data using SPI?

Even in the evmc66x_spi.c example file, the function spi_xfer controls the flag TXFULL, while spi_write_word checks TXINTFLG.

0 Ganapathi Dhandapani95 over 11 years ago

Hi Gabriele,

Both flags are used in transmitter side.

In spi_xfer() load the TX data to SPIDATx register after TX buffer is full (TXFULL).

In spi_write_word() load the TX data to SPIDATx register and check the TX buffer is empty interrupt flag.

Thanks,

0 Gabriele_Giannini over 11 years ago in reply to Ganapathi Dhandapani95

ok but in a transmit loop what of the 2 flag is better to poll?

or it's the same?

0 Ganapathi Dhandapani95 over 11 years ago in reply to Gabriele_Giannini

TXINTFLG flag is better to used on transmit loop. It is interrupt based.

TXFULL flag polling based.

Thanks,

0 Gabriele_Giannini over 11 years ago in reply to Ganapathi Dhandapani95

Thanks.

So, if in my code i don't want to use interrupt but i prefer to poll the transmission status i can use TXFULL

0 Raja over 11 years ago in reply to Gabriele_Giannini

Hi,

If you have any follow up questions, please post here. Otherwise, please help us to close this thread.

Thanks.

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