The MPC5554DEMO platform HAL package is loaded automatically when eCos is configured for an mpc5554demo 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.
The MPC5554DEMO platform HAL package supports three separate startup types:
This is the startup type which is normally used during application development. The board has RedBoot programmed into flash at location 0x00020000 and boots from that location. powerpc-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.
This startup type can be used for finished applications which will be programmed into flash at location 0x00020000. The application will be self-contained with no dependencies on services provided by other software. eCos startup code will perform all necessary hardware initialization.
This startup type can be used for finished applications which will be loaded into external RAM via a JTAG debugger. The application will be self-contained with no dependencies on services provided by other software. The JTAG debugger should initialize the hardware enough to load the code into RAM, eCos startup code will perform any further hardware initialization.
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 supposed to make use of services provided by a
ROM monitor, via the eCos virtual vector mechanism, then the
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.
The MPC5554 microcontroller contains 2MiB of flash memory. The
CYGPKG_DEVS_FLASH_MPC5500 package contains all the
code necessary to support access to the flash. The MPC5554DEMO
platform HAL package contains definitions that customize the driver to
the MPC5554DEMO board.
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.
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 are two flags specific to this port:
The powerpc-eabi-gcc compiler supports many variants of the PowerPC architecture. A
-moption should be used to select the specific variant in use. The MPC5554 is a Book E processor, and the current tools do not have an option to select this processor directly so instead we select a processor that is also Book E based and which is supported: the MPC8540.
The PowerPC processor used in the MPC5554DEMO boards does not have a floating point unit. Therefore it is necessary to translate any floating point operations into software emulation. This option tells the compiler to do that.