topic Re: SPI0 fail with Framesize = 16 in Vybrid Processors

SPI0 fail with Framesize = 16

sandrobastos — Mon, 09 Dec 2013 16:53:35 GMT

Hi,

I'm trying to set my SPI0 to 16 bits through:

	// Framesize = 16
	param = 16;
	printf ("Changing the Framesize to %d bits ... ", param);
	if (SPI_OK == ioctl (spifd, IO_IOCTL_SPI_SET_FRAMESIZE, &param))
	{
	printf ("OK\n");
	}
	else
	{
	printf ("ERROR\n");
	}

The procedure is accepted and I receive an OK and read 16 when a GET_FRAMESIZE is issued.

The problem is I cannot write at the device; it always returns error, only with 16 bits, if 8 is set, it works fine.

How can I work with SPI in 16 bits?

karina_valencia — Wed, 11 Dec 2013 19:24:29 GMT

juangutierrez please review this case and provide follow up.

juangutierrez — Wed, 11 Dec 2013 19:57:16 GMT

Is this Linux or MQX?

Are both slave and master devices configured for 16bits?

Is it possible to share your application test and a way to test it in our side?

karina_valencia — Wed, 11 Dec 2013 20:07:54 GMT

MQX

juangutierrez — Wed, 11 Dec 2013 22:13:30 GMT

Can you post which function are you calling for writing to the device and what kind of error you get, please?

sandrobastos — Thu, 12 Dec 2013 09:43:56 GMT

Hi Juan,

Thanks for replying.

I'm using MQX. Yes, the slave is 16 bits; it's an LCD display.

I'm using 'fputc(data, spifd)' to write the data and, when configured to 16 bits, I get an IO_ERROR (-1) and nothing happens on the SDA, SCL, lines.

The fputc() enables de CS to the device and 'fflush()' disables it.

I solved the problem by sending two bytes (2 x fputc()) and then 'fflush()', this way the CS is only disabled after 16 bits is transmitted.

Anyway, I think the SPI should work fine at 16 bits.

Thanks and regards.

juangutierrez — Thu, 12 Dec 2013 16:14:26 GMT

Hi Sandro

Glad to hear you get it working.

Not sure, but the error might be because the fputc is intended for writing just one character (1 byte) to the stream.

Maybe you want to try using fputs instead, and sending a two-character string.

Let us know if that works.

Thanks

juan gutierrez

sandrobastos — Thu, 12 Dec 2013 16:39:43 GMT

Hi Juan,

You are right, I changed fputc by fwrite and it's working fine!

thank you very much.

cheers