Micrium uCOS-II ARM Port
Introduction
uC/OSII has been running on ARM based processors since 1995 (in fact C/OS V1.x has).
There has been a number of ARM ports posted on the Micrium web site. The differences
have mostly to do with differences in compilers and what target board they run on.
This application note describes the official’ Micrium port for uC/OSII. Figure 11 shows a
block diagram showing the relationship between your application, uC/OSII, the port code
and the BSP (Board Support Package). Relevant sections of this application note are
referenced on the figure.
Note that the port described in this application note applies to both ARM7 and ARM9
processors and you can use this port for both ARM and Thumbbased applications.
Previous ports either worked in ARMmode or in Thumbmode. This port handles both.
Relationship between modules.
The ARM programmer’s model
Some of the most popular variant of the ARM processors are the ARM7TDMI and
ARM92xT. The four letters stand for:
T (Thumb)
The T stands for Thumb instruction set which addresses the issue of code
density. Specifically, Thumb mode allows instructions to be 16bits instead of
32bits thus reducing code density. A processor having the T suffix can thus
run Thumb code.
D (Debug)
The D stands for debug support. This means that the specific ARM7 you are
using offers onchip debug support, generally through a JTag interface.
M (Multiply)
The M means that the CPU contains a hardware multiply instruction.
I (EmbeddedICE macrocell)
Is the debug hardware built into the processor that allows breakpoints and
watchpoints to be set.
ARM Register Model
The visible registers in an ARM processor are shown in Figure 21. The ARM has a total of
37 registers. Each register is 32 bits wide. At any time, only 18 of those registers are
directly visible’ by the processor: R0 through R15, CPSR and SPSR (SPSR is not visible
in SYS mode).
R0-R12
Micrium uCOS-II ARM Port — EmbSys 2012 documentation http://courses.washington.edu/cp105/uCOS Port/uCOS Port.html
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