Configuration

Name

Configuration -- Platform-specific Configuration Options

Overview

The MX1ADS/A platform HAL package is loaded automatically when eCos is configured for a mx1ads_a or mxlads_a 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 MC9328MX1 SoC is supported by a separate HAL, CYGPKG_HAL_ARM_ARM9_MC9328MXL, which supports all the devices on the MC9328MX1/L that eCos uses.

Startup

The MX1ADS/A platform HAL package supports four 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 at physical address 0x10000000. The application will be self-contained with no dependencies on services provided by other software. eCos startup code will perform all necessary hardware initialization.

ROMRAM

This startup type can be used for finished applications which will be programmed into flash at physical location 0x10000000. However, when it starts up the application will first copy itself to RAM at 0x00000000 and then run from there. RAM is generally faster than flash memory, so the program will run more quickly than a ROM-startup application. The application will be self-contained with no dependencies on services provided by other software. eCos startup code will perform all necessary hardware initialization.

SRAM

This startup type is used for applications that are downloaded via the JTAG interface. The application is loaded into SRAM at location 0x08040000 and started by executing from that address. The application will be self-contained with no dependencies on services provided by other software. eCos startup code will perform all necessary hardware initialization. However, it is assumed that the machine has been set up from the JTAG interface as described earlier for installing RedBoot.

This configuration is primarily present to provide support for installing RedBoot in the FLASH. It has some limitations with regard to functionality since the MMU is not enabled and no exception vectors are installed at location zero, hence no interrupts can be handled.

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 MX1ADS/A board contains two 16 bit AMD Am29PDL127H flash devices arranged in parallel to form a 32 bit wide interface. The CYGPKG_DEVS_FLASH_AMD_AM29XXXXX package contains all the code necessary to support these parts and the CYGPKG_DEVS_FLASH_ARM_MX1ADS_A package contains definitions that customize the driver to the MX1ADS/A board.

Ethernet Driver

The MX1ADS/A board contains a Cirrus Logic CS8900A ethernet MAC. The CYGPKG_DEVS_ETH_CL_CS8900A package contains all the code necessary to support this device and the CYGPKG_DEVS_ETH_ARM_MX1ADS_A package contains definitions that customize the driver to the MX1ADS/A board.

System Clock

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.

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 is just one flag specific to this port:

-mcpu=arm9

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=arm9 is the correct option for the ARM920T CPU in the MC9328MXL.

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