Configuration — Platform-specific Configuration Options
The AT91SAM9G45-EKES platform HAL package is loaded automatically
when eCos is configured for the
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 platform HAL package supports two separate startup types:
- 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.
- This startup type can be used for finished applications which will be programmed into NAND Flash. 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 is the startup type which can be used during application development via a JTAG device such as the PEEDI. arm-eabi-gdb is used to load a JTAG startup application into memory and debug it. Hardware setup is divided between the initialization section of the PEEDI configuration file and software in the loaded application.
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 AT91SAM9G45-EKES board contains a 4Mbyte Atmel AT45 DataFlash
package contains all the code necessary to support this part and
the platform HAL package contains definitions that customize the
driver to the AT91SAM9G45-EKES board. This driver is not active
until the generic Flash support package,
CYGPKG_IO_FLASH, is included in the
The AT91SAM9G45-EKES board uses the AT91SAM9G45's internal EMAC
ethernet device attached to an external Davicom DM9161A PHY. The
CYGPKG_DEVS_ETH_ARM_AT91 package contains all
the code necessary to support this device and the platform HAL
package contains definitions that customize the driver to the
AT91SAM9G45-EKES board. This driver is not active until the generic
Ethernet support package,
CYGPKG_IO_ETH_DRIVERS, is included in the
The AT91SAM9G45-EKES board uses the AT91SAM9G45's internal RTC
contains all the code necessary to support this device. This
driver is not active until the generic wallclock device support
CYGPKG_IO_WALLCLOCK, is included in
The AT91SAM9G45-EKES board uses the AT91SAM9G45's internal watchdog
contains all the code necessary to support this device. Within
that package the
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
The ATSAM926x processor will boot with watchdog support enabled, and the watchdog configuration is write-once. That is, if it is disabled, it cannot be re-enabled. Due to its nature, RedBoot disables the watchdog when it starts so any eCos applications with watchdog support enabled that are run by RedBoot will not function correctly.
USART Serial Driver
The AT91SAM9G45-EKES board uses the AT91SAM9G45's internal USART
serial support as described in the SAM9 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 1 which is mapped to virtual
vector channel 1 and "
/dev/ser1". The debug
port has no additional signals, but USART 1 supports RTS/CTS.
As the SAM MCI driver is included in the hardware-specific
configuration for this target, nothing is
required to load it. Similarly the MMC/SD bus driver layer
CYGPKG_DEVS_DISK_MMC) is automatically
included as part of the hardware-specific configuration for this
target. All that is required to enable the support is to include
the generic disk I/O infrastructure package
CYGPKG_IO_DISK), along with the intended
filesystem, typically, the FAT filesystem
CYGPKG_FS_FAT) and any of its package
CYGPKG_LINUX_COMPAT for FAT).
If the generic disk I/O infrastructure is needed for some
other reason, and you do not wish to also include the MCI driver,
then the configuration option within this platform HAL
CYGPKG_HAL_ARM_ARM9_SAM9G45EK_MMCSD can be
used to forcibly disable it.
Various options can be used to control specifics of the SAM MCI driver. Consult the SAM MCI driver documentation for information on its configuration.
The MCI driver at present can only handle a single MCI interface,
the configuration option
Only MMC/SD socket 1 permits detection of the write-protect (or "lock") switch present on SD cards. "Locked" cards will therefore not be detected on socket 0 which means that despite the switch position, it is still possible to write to them since the lock switch does not physically enforce write protection.
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 just three flags specific to this port:
The arm-eabi-gcc compiler supports
many variants of the ARM architecture. A
-moption should be used to select the specific variant in use, and with current tools
-mcpu=arm9is the correct option for the ARM926EJ CPU in the AT91SAM9G45.
The arm-eabi-gcc compiler will
compile C and C++ files into the Thumb instruction set when
this option is used. The best way to build eCos in Thumb mode
is to enable the configuration option
This option allows programs to be created that mix ARM and
Thumb instruction sets. Without this option, some memory can be
saved. This option should be used if -mthumb is used. The best
way to build eCos with Thumb interworking is to enable the
The HAL port includes a low-level driver to access the on-board
Micron MT29F2G08ABD NAND flash memory chip. To enable the driver,
activate the CDL option
CYGPKG_HAL_SAM9G45EK_NAND and ensure that the
CYGPKG_DEVS_NAND_MICRON_MT29F package is
present in your eCos configuration.
If set, this option configures the driver to wait for NAND operations to complete by waiting for the chip to deassert its Busy line. This is the default behaviour and is recommended, but may be disabled if you need to use the line (PIO C8) for some other purpose. (If disabled, the memory controller is configured to stall NAND accesses until they complete, which will interfere with multi-threading.)
The number of microseconds delay in the polling loops which wait for NAND operations to complete.
Partitioning the NAND chip
The NAND chip must be partitioned before it can become available to applications.
A CDL script which allows the chip to be manually partitioned is
if you choose to use this, the relevant data structures will
automatically be set up for you when the device is
initialised. By default, the manual config CDL script sets up a
single partition (number 0) encompassing almost the entire
device. The first block of the device contains AT91Bootstrap and
the second and subsequent blocks contain RedBoot, or a ROM
application. The first partition should therefore start above
this. The default is set to block 8, leaving 1MiB at the base of
NAND for bootstrapping.
It is possible to configure the partitions in some other way,
should it be appropriate for your setup, for example to read a
Linux-style partition table from the chip. To do so you will have
to add appropriate code to
|2022-10-12||eCosPro Non-Commercial Public License|