eCos Support for the Atmel AT91SAM7A2-EK — Overview


This document covers the configuration and usage of eCos and RedBoot on the Atmel AT91SAM7A2-EK Evaluation Kit. The AT91SAM7A2-EK Evaluation Kit contains the AT91SAM7A2 processor, 512KiB of SRAM, 2MiB of parallel NOR Flash memory, external connections for a singe serial channel, CAN and LIN ports. eCos support for the devices and peripherals on the AT91SAM7A2 is described below.

For typical eCos development, a RedBoot image is programmed into the flash memory, and the board will boot into this image from reset. RedBoot provides gdb stub functionality so it is then possible to download and debug stand-alone and eCos applications via the gdb debugger. Applications may also be loaded into RAM via a JTAG debugger, or may be programmed into flash.

This documentation is expected to be read in conjunction with the AT91 processor HAL and AT91SAM7 variant HAL documentation and further device support and subsystems are described and documented there.

Supported Hardware

The parallel NOR flash memory consists of 31 blocks of 16KiBytes each, followed by 8 blocks of 8KiBytes each. In a typical setup, the first 128 KiBytes are reserved for the use of the RedBoot image. The topmost 8 blocks are used to manage the flash and hold RedBoot fconfig values. The remaining blocks can be used by application code. There are 30 blocks available between 0x40020000 and 0x401EFFFF.

There is a serial driver CYGPKG_IO_SERIAL_ARM_AT91 which supports both the Debug Unit and USART serial devices. The debug serial port can be used for communication. If RedBoot is installed, it uses the Debug Unit serial device. The serial driver package is loaded automatically when configuring for the AT91SAM7A2-EK target.

There is a watchdog driver CYGPKG_DEVICES_WATCHDOG_ARM_AT91. This driver is also loaded automatically when configuring for the AT91SAM7A2-EK target.

In general, devices (PIO, UARTs, etc.) are initialized only as far as is necessary for eCos to run. Other devices (RTC, I²C, SPI etc.) are not touched unless the appropriate driver is loaded, although in some cases, the HAL boot sequence will set up the appropriate PIO configuration.


The AT91SAM7A2-EK support is intended to work with GNU tools configured for an arm-elf target. The original port was undertaken using arm-elf-gcc version 3.4.4, arm-elf-gdb version 6.3, and binutils version 2.15.