Configuration

Configuration
	Chapter 267. ARM Versatile 926EJ-S Board Support

Overview

The VPB926EJS platform HAL package is loaded automatically when eCos is configured for a vpb926ejs 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 VPB926EJS platform HAL package supports four separate startup types:

RAM: This is the startup type which is normally used during application development. The board has RedBoot programmed into flash and boots into that initially. arm-eabi-gdb is then used to load a RAM startup application into memory and debug it. It is assumed that the hardware has already been initialized by RedBoot. By default the application will use the eCos virtual vectors mechanism to obtain certain services from RedBoot, including diagnostic output.
ROM: This startup type can be used for finished applications which will be programmed into flash at physical address 0x34000000. The application will be self-contained with no dependencies on services provided by other software. eCos startup code will perform all necessary hardware initialization.
ROMRAM: This startup type can be used for finished applications which will be programmed into flash at physical location 0x34000000. However, when it starts up, the application will first copy itself to RAM at 0x00000000 and then run from there. RAM is generally faster than flash memory, so the program will run more quickly than a ROM-startup application. The application will be self-contained with no dependencies on services provided by other software. eCos startup code will perform all necessary hardware initialization.
SRAM: This startup type exists only to support the installation of RedBoot via the JTAG interface. Functionally, it is equivalent to the ROM startup type except that the executable image is loaded into the static RAM at 0x38000000 rather than the flash ROM. It is of little use for other applications.

RedBoot 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 RedBoot.

If the application is required 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 RAM startup, disabled otherwise. It can be manually disabled for 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 VPB926EJS board contains two 32Mb 28F256K3 Intel StrataFlash flash devices, giving 64MB of flash in total. The CYGPKG_DEVS_FLASH_STRATA_V2 package contains all the code necessary to support these parts and the VPB926EJS platform HAL package contains definitions that customize the driver to the VPB926EJS board.

Ethernet Driver

The VPB926EJS board contains a SMSC LAN91C111 ethernet controller. The CYGPKG_DEVS_ETH_SMSC_LAN91CXX package contains all the code necessary to support this device and the CYGPKG_DEVS_ETH_ARM_VPB926EJS package contains definitions that customize the driver to the VPB926EJS board.

System Clock

By default, the system clock interrupts once every 10ms, corresponding to a 100Hz clock. This can be changed by the configuration option CYGNUM_HAL_RTC_DENOMINATOR which corresponds to the clock frequency. Other clock-related settings are recalculated automatically if the denominator is changed.

Compiler Flags

The platform 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 is just one flag specific to this port:

-mcpu=arm9: The arm-eabi-gcc compiler supports many variants of the ARM architecture. A -m option should be used to select the specific variant in use, and with current tools -mcpu=arm9 is the correct option for the ARM926E CPU.


Setup		The HAL Port

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