This documentation explains how the eCos HAL specification has been
mapped onto the MPC5554DEMO hardware, and should be read in conjunction
with that specification. The MPC5554DEMO platform HAL package complements
the PowerPC architectural HAL and the MPC55XX variant HAL. It provides
functionality which is specific to the target board.
Following a hard or soft reset the HAL will initialize or
reinitialize most of the on-chip peripherals. There is an exception
for RAM startup applications which depend on a ROM monitor for certain
For ROM startup, the HAL will perform additional
initialization, setting up the external RAM and programming the
various internal registers. This is all done in the
hal_hardware_init function in the assembler
source file mpc5554demo.S.
Linker Scripts and Memory Maps
The platform HAL package provides the memory layout information needed
to generate the linker script. The key memory locations are as follows:
This is located at address 0x00000000 of the physical memory
space. It is mapped by the BAM 1-1 to virtual address 0x00000000 with
caching enabled, and by eCos to 0x10000000 with caching disabled.
This is located at address 0x20000000 of the physical memory space.
The first 512 bytes are used for the VSR table and the next 256 bytes
are normally used for the eCos virtual vectors, allowing RAM-based
applications to use services provided by the ROM monitor. The next 512
bytes are used for a shared interrupt state table, recording mask and
priority values for each interrupt source. For ROM and JTAG startup, all
remaining SRAM is available. For RAM startup, available RAM starts at
location 0x00008000, with the bottom 32kiB reserved for use by
RedBoot. The SRAM is mapped 1-1 with cache enabled at virtual address
0x20000000 and uncached at 0x30000000.
These are available via 1-1 uncached mappings at 0xFFF00000 and
The tm_basic kernel test gives statistics gathered about the real-time
characterization and performance of the kernel. The sample output is shown here
The MPC5554DEMO platform HAL does not affect the implementation of other
parts of the eCos HAL specification. The
MPC55XX variant HAL, and the PowerPC architectural HAL documentation
should be consulted for further details.