The HAL Port

Overview

This documentation explains how the eCos HAL specification has been mapped onto the STB200 hardware, and should be read in conjunction with that specification. The STB200 platform HAL package complements the MIPS architectural HAL, the PNX8310 variant HAL, and the PNX83xx support HAL. It provides functionality which is specific to the target board.

Startup

Following a hard or soft reset the HAL will set up some of the on-chip peripherals appropriately for eCos, but most peripherals are left to their default settings. Full details of this initialization can be found in the function hal_platform_init in stb200.c.

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:

Clock Support

The platform HAL provides configuration options for the eCos system clock. This always uses the hardware timer TMR1, part of the PR1910 core and is accessed via coprocessor 0. The actual HAL macros for managing the clock are provided by the PNX8310 variant HAL. The specific numbers used are a characteristic of the platform because they depend on the processor speed. TMR2 is used by the gprof-based profiling code, or is available for application use when profiling is not enabled. TMR3 is normally used only for the watchdog.

MIPS16 Support

The STB200 platform HAL enables MIPS16 support in the architecture HAL. This allows application code to be compiled using MIPS16 options and linked against the 32 bit mode eCos library.

To compile for MIPS16 the standard flags that are used in eCos and exported to the ecos.mak file should be used except that the -mips2 flag should be replaced by -mips16 -fwritable-strings. The -mips16 option enables MIPS16 compilation and the -fwritable-strings option is a work-around for a bug in the compiler.

Other Issues

The STB200 platform HAL does not affect the implementation of other parts of the eCos HAL specification.