spi_setup

uni_student · Posted: Tue Sep 25, 2007 9:16 pm

Hi, just need some verification that the following setup

setup_spi(SPI_MASTER | SPI_XMIT_L_TO_H | SPI_H_TO_L | SPI_CLK_DIV_16);

I have a PIC18F452 and need to communicate to a m25p40 (spi-eeprom)

The eprom reads on the rising edge and transmits on the falling edge.

Is the above setup for the PIC correct, because i havent been able to communicate with it so far? Has anyone had experience with this eprom?

Ive tried to debug it using LEDS and havent been able to read the values from the epromm correctly.
Any help appreciated, Cheers

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Read my post in this thread, which explains how to determine the
correct setup for the SPI mode and SPI clock frequency.
http://www.ccsinfo.com/forum/viewtopic.php?t=31594

Also make sure you have correctly connected the SPI pins on the PIC to
the SPI pins on the other device. See my post in this thread:
http://www.ccsinfo.com/forum/viewtopic.php?t=32118

Guest · Posted: Tue Sep 25, 2007 9:57 pm

Thanx for quick reply

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

You don't have to do that. I don't think any SPI device operates that
way. Just pick one of the two modes, and set it up for that.
I recommend using Mode 0. Look in the thread that I mentioned, and
add the #define statements for the SPI modes to your program. Then
use the constant for Mode 0, and put it in your setup_spi() statement, as
shown in the sample code in that post.