Configuration

Name

Configuration -- Platform-specific Configuration Options

Overview

The Zoom L138 platform HAL package is loaded automatically when eCos is configured for the zoom-l138 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 platform HAL package supports two 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. 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 also be used for applications loaded via JTAG.

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 configuration option CYGSEM_HAL_USE_ROM_MONITOR 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.

Flash Driver

The Zoom board contains an 8Mbyte Numonyx M25P64 SPI serial NOR flash device. The CYGPKG_DEVS_FLASH_SPI_M25PXX package contains all the code necessary to support this part and the platform HAL package contains definitions that customize the driver to the Zoom L138 board. This driver is not active until the generic Flash support package, CYGPKG_IO_FLASH, is included in the configuration.

This driver is capable of supporting the JFFS2 filesystem. However, note that the SPI interface means that this file system has reduced bandwidth and increased latency compared with other implementations. All that is required to enable the support is to include the filesystem (CYGPKG_FS_JFFS2) and any of its package dependencies (including CYGPKG_IO_FILEIO and CYGPKG_LINUX_COMPAT) together with the flash infrastructure (CYGPKG_IO_FLASH).

Ethernet Driver

The Zoom L138 board uses the OMAP L138's internal EMAC ethernet device attached to an external SMSC LAN8710A PHY. The CYGPKG_DEVS_ETH_ARM_OMAP package contains all the code necessary to support this device and the platform HAL package contains definitions that customize the driver to the ZOOM L138 board. This driver is not active until the generic Ethernet support package, CYGPKG_IO_ETH_DRIVERS, is included in the configuration.

RTC Driver

The ZOOM L138 board uses the OMAP L138's internal RTC support. The CYGPKG_DEVICES_WALLCLOCK_ARM_OMAP_L1XX package contains all the code necessary to support this device. This driver is not active until the generic wallclock device support package, CYGPKG_IO_WALLCLOCK, is included in the configuration.

Watchdog Driver

The Zoom L138 board uses the OMAP L138's internal watchdog support. The CYGPKG_DEVICES_WATCHDOG_ARM_OMAP_L1XX package contains all the code necessary to support this device. Within that package the CYGNUM_DEVS_WATCHDOG_ARM_OMAP_L1XX_DESIRED_TIMEOUT_MS 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 configuration.

UART Serial Driver

The Zoom L138 board uses the OMAP L138's internal UART serial support as described in the OMAP L1xx processor HAL documentation. Only one serial connector is available on the board, which is connected to UART2. This connector has the RTS/CTS hardware flow control lines connected in addition to the data lines.

MMC/SD Driver

As the OMAP L1xx MMC/SD driver is part of the OMAP L1xx HAL, 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 dependencies (including CYGPKG_LIBC_STRING and CYGPKG_LINUX_COMPAT for FAT).

Various options can be used to control specifics of the MMC/SD driver. Consult the OMAP L1xx HAL documentation for information on its configuration.

This board has the MMC/SD socket's card detect and write protect lines connected to GPIO lines. The card detect line is additionally monitored by an interrupt handler. Thus the disk I/O layer's removeable media support will detect when cards have been inserted or removed, and the FILEIO layer's automounter can be used.

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 are just three flags specific to this port:

-mcpu=arm926ej-s

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=arm926ej-s is the correct option for the ARM926EJ-S CPU in the OMAP L1xx.

-mthumb

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 CYGHWR_THUMB.

-mthumb-interwork

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 configuration option CYGBLD_ARM_ENABLE_THUMB_INTERWORK.

2017-02-09
Documentation license for this page: eCosPro License