EBI SDRAM Example for xplain Documentation

Introduction

This example demonstrates how to use the external bus interface driver.

Main Files

• ebi_sdram_example.c example application
• conf_board.h board configuration

drivers/ebi/ebi.h driver

The external bus interface driver is described in the External Bus Interface (EBI) section.

Device Info

All AVR XMEGA devices with an external bus interface (EBI) and a SDRAM wired to the EBI can be used. This example has been tested with the following setup:

• Xplain evaluation kit

Example Configuration

The example code is configurable by defining the following symbols in the conf_board.h header file.

• CONFIG_HAVE_HUGEMEM must be defined to use the 8-bit AVR huge memory interface. See Data in Huge Data Memory Space for more information.
• BOARD_EBI_SDRAM_BASE must be defined and given the value of the base address of the external SDRAM device.
• BOARD_EBI_SDRAM_SIZE must be defined and given the size of the external SDRAM device.

Description of the example

The example will configure the external bus interface to address the SDRAM device at a board configurable address. The SDRAM will addressable through Data in Huge Data Memory Space.

After configuring the external bus interface and initializing the SDRAM the example code will run through three test applications which can detect faults to address lines, data lines and finally a data integrity test which will write both 0s and 1s to the entire SDRAM device.

This example uses the on-board LEDs to provide user feedback, the output from the LEDs are as follows:

• LED0: external bus interface configured
• LED1: SDRAM is ready
• LED2: data bus test completed successfully
• LED3: address bus test completed successfully
• LED4: data integrity test completed successfully
• LED7: example application has completed

If LED7 lights up before LED0 to LED4 has been lit, then the first of the missing lit LEDs indicates that the corresponding test has failed.

The test requires about 25 seconds to complete on an 8 MB SDRAM device with a 64 MHz EBI configuration.

Dependencies

This example depends on the following modules:

• External Bus Interface (EBI)
• General Purpose Input/Output for LED control
• Sleep manager for being able to go to sleep

Compilation Info

This software was written for the GNU GCC and IAR for AVR. Other compilers may or may not work.

Contact Information

For further information, visit Microchip.