This application uses module_spi_master to read and write data to the SPI slave flash device on the board.
Note: Running this program will overwrite any existing data in the flash.
The Makefile is found in the top level directory of the application. It uses the general XMOS makefile in module_xcommon which compiles all the source files in the application and the modules that the application uses. We only have to add a couple of configuration options.
Firstly, this application is for an XK-1 development board so the TARGET variable needs to be set in the Makefile:
# The TARGET variable determines what target system the application is
# compiled for. It either refers to an XN file in the source directories
# or a valid argument for the --target option when compiling.
TARGET = XK-1
Secondly, the application name must be set:
# The APP_NAME variable determines the name of the final .xe file. It should
# not include the .xe postfix. If left blank the name will default to
# the project name
APP_NAME = app_spi_master_demo
Finally, the application will use the SPI master module. We state that the application uses this as follows:
# The USED_MODULES variable lists other module used by the application.
USED_MODULES = module_spi_master
The spi_conf.h file is found in the src/ directory of the application. This file contains a series of #defines that configure the SPI component. The possible #defines that can be set are described in Configuration Defines.
If not set, default values in the spi_master header file will be used.
Within this application we set the SPI mode to 3, and the default SPI clock divider to 2 (giving a SPI clock frequency of 25MHz).
// Copyright (c) 2011, XMOS Ltd., All rights reserved
// This software is freely distributable under a derivative of the
// University of Illinois/NCSA Open Source License posted in
// LICENSE.txt and at <http://github.xcore.com/>
#define DEFAULT_SPI_CLOCK_DIV 2
#define SPI_MASTER_MODE 3
The flash chip on the XK-1 board supports SPI modes 0 and 3, and clock frequencies up to 104MHz. The demo can be recompiled and run in either SPI mode, and larger clock dividers.
To make use of the SPI master module app_spi_master_demo must contain the following line:
#include "spi_master.h"
This application is contained in spi_master_demo.xc. Within this file is the main() function which sets up the SPI interface, and then calls the read_jedec_id(), write_speed_test(), and read_speed_test() functions to test the interface.
The read_jedec_id() function reads the device ID register and checks the returned value is as correct, outputting both the expected and actual values.
The write_speed_test() function writes a page of data to the flash, and then reads it back to ensure it was written correctly. The time taken to write the data is output.
The read_speed_test() function reads 50kB of data from the flash into a buffer. The time taken to complete the read is output.