Digital Signal Processing Reference
In-Depth Information
for devices with memory size in the tens to hundreds of kilobytes and with real-
time requirements.
eCos was developed by Cygnus Solutions and was later bought by Red Hat. In
2002, Red Hat ended development of eCos and the developers then formed,
eCosCentric, in order to continue development and provide support for eCos.
Red Hat agreed to transfer its eCos copyrights to the Free Software Foundation
in October 2005. eCosCentric has a version of their eCosPro distribution that
has been ported to the Nios II processor.
18.3 µC/OS-II
µC/OS-II is a highly portable, scalable, preemptive, real-time, multitasking
kernel for microprocessors and microcontrollers. µC/OS-II is written in C
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.
Since its introduction in 1992, µC/OS-II has been used in a wide array of
products including cell phones, climate controls, audio/video processors, credit
card processing units, and electrical instrumentation.
µC/OS-II can manage up to 255 tasks and provides services such as
semaphores, mutual exclusion semaphores, event flags, message mailboxes,
message queues, task management, fixed-size memory block management, and
time/timer management.
µC/OS-II has been ported to the Nios II processor (Altera usually refers to it as
MicroC/OS-II). Altera distributes MicroC/OS-II in the full commercial version
of the Nios II EDS software and supports the Nios II port of the MicroC/OS-II
kernel. Examples of MicroC/OS-II programs are included with the Nios II EDS
software.
The license for the Nios II MicroC/OS-II port is available from Micrium.
Micrium offers free OS licensing for universities and students. A MicroC/OS-II
reference manual and tutorial are available on the DVD and from Altera.
As seen in Figure 18.3, the MicroC/OS-II kernel operates on top of the
hardware abstraction layer (HAL) system library for the Nios II processor. By
using the HAL, programs based on MicroC/OS-II are more portable to other
Nios II hardware systems and are somewhat flexible with respect to hardware
changes. MicroC/OS-II programs can use all HAL services and use the HAL
APIs described earlier in this text.
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The internal architecture of µC/OS-II is described in "µC/OS-II, The Real-Time Kernel" by Jean J. Labrosse.
