This documentation explains how the eCos HAL specification has
been mapped onto the MCB1700 board hardware, and should be
read in conjunction with that specification. The MCB1700
platform HAL package complements the ARM architectural HAL and the
LPC1XXX variant HAL. It provides functionality which is specific to
the target board.
Startup
Following a hard or soft reset the HAL will initialize or
reinitialize many of the on-chip peripherals. There is an
exception for RAM startup applications which depend on a ROM
monitor for certain services.
For ROM and JTAG startup, the HAL will perform additional
initialization, programming the various internal registers
including the PLL, peripheral clocks and GPIO pins. The details
of the early hardware startup may be found in the
src/mcb1700_misc.c in both
hal_system_init and
hal_platform_init.
Memory Map
The platform HAL package provides the memory layout information
needed to generate the linker script. The key memory locations are
as follows:
Internal RAM
This is located at addresses 0x10000000 and 0x2007C000 of the
memory space, and is 64KiB in size, divided into two 32KiB
blocks. The eCos VSR table occupies 512 bytes at 0x10000000. The
virtual vector table starts at 0x10000200 and extends to
0x10000300. The top
CYGNUM_HAL_COMMON_INTERRUPTS_STACK_SIZE
bytes down from 0x10008000 are reserved for the interrupt
stack.
The second 32KiB block is divided into two 16KiB parts,
reflecting its organization in the hardware. The lower 16KiB,
at 0x2007C000, are available for application use. The upper
16KiB, at 0x20080000, are used by the ethernet driver for
packet buffers. If the ethernet device is not used, this memory
may be used by applications.
Internal FLASH
This is located at address 0x00000000 of the memory space.
This region is 512KiB in size. ROM applications are by default
configured to run from this memory.
On-Chip Peripherals
These are accessible at locations 0x40000000 and 0xE0000000
upwards. Descriptions of the contents can be found in the
LPC1XXX User Manual.
Linker Scripts
The platform linker scripts define the following symbols:
hal_vsr_table
This defines the location of the VSR table. This is set to
0x10000000 for all startup types, and space for 128 entries is
reserved.
hal_virtual_vector_table
This defines the location of the virtual vector table used to
communicate between an ROM monitor and an eCos
application. This is allocated right after the VSR table, at
0x10000200. To permit expansion and possible addition of other
tables, the linker scripts then allocate further sections from
0x10000400.
hal_startup_stack
This defines the location of the startup stack. This is
allocated to the top of internal SRAM, 0x10008000. For RAM
applications the linker script allocates this
stack CYGNUM_HAL_COMMON_INTERRUPTS_STACK_SIZE
bytes below the top of RAM to allow space for the stubrom's
interrupt stack.
