Overview

The AT91SAM7A3-EK platform HAL package is loaded automatically when eCos is configured for the at91sam7a3ek target. It should never be necessary to load this package explicitly. Unloading the package should only happen as a side effect of switching target hardware.

Startup

The platform HAL package supports three separate startup types:

GDB Stubs and Virtual Vectors

If the application is intended to act as a ROM monitor, providing services for other applications, then the configuration option CYGSEM_HAL_ROM_MONITOR should be set. Typically this option is set only when building the GDB Stubs.

If the application is supposed to make use of services provided by a ROM monitor, via the eCos virtual vector mechanism, then the configuration option CYGSEM_HAL_USE_ROM_MONITOR should be set. By default this option is enabled when building for a RAM startup, disabled otherwise. It can be manually disabled for a RAM startup, making the application self-contained, as a testing step before switching to ROM startup.

If the application does not rely on a ROM monitor for diagnostic services then the serial port will be claimed for HAL diagnostics.

Flash Driver

The AT91SAM7A3-EK board contains a quantity of on-chip flash memory. The CYGPKG_DEVS_FLASH_AT91 package contains all the code and data definitions necessary to support this part. This driver is not active until the generic Flash support package, CYGPKG_IO_FLASH, is included in the configuration.

Watchdog Driver

The AT91SAM7A3-EK board use the AT91SAM7A3's internal watchdog support. The CYGPKG_DEVICES_WATCHDOG_ARM_AT91WDTC package contains all the code necessary to support this device. Within that package the CYGNUM_DEVS_WATCHDOG_ARM_AT91WDTC_DESIRED_TIMEOUT_MS configuration option controls the watchdog timeout, and by default will force a reset of the board upon timeout. This driver is not active until the generic watchdog device support package, CYGPKG_IO_WATCHDOG, is included in the configuration.

Note that on the AT91, the on-chip watchdog peripheral always starts running immediately, and so in configurations that do not include the watchdog driver, it is always disabled via its write-once register. In configurations which include the watchdog driver obviously the watchdog is not disabled otherwise it could not be subsequently re-enabled, and so the application must start and periodically reset the watchdog from the very beginning of execution.

USART Serial Driver

The AT91SAM7A3-EK board use the AT91SAM7A3's internal USART serial support as described in the AT91 processor HAL documentation. Two serial ports are available: the serial debug port which is mapped to virtual vector channel 0 in the HAL diagnostic driver or "/dev/dbg" in the interrupt-driven driver; and USART 0 which is mapped to virtual vector channel 1 and "/dev/ser0". Only USART 0 supports modem control signals such as those used for hardware flow control.

Compiler Flags

The SAM7 variant HAL defines the default compiler and linker flags for all packages, although it is possible to override these on a per-package basis. Most of the flags used are the same as for other architectures supported by eCos. There are just three flags specific to this port: