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Recent Updates to EventHelix.com.
(Please feel free to forward this e-mail to your friends interested in
Realtime and Embedded Software Development)
DMA and Interrupt Handling
In this article we will cover Direct Memory Access (DMA) and
Interrupt Handling. Knowledge of DMA and interrupt handling would be
useful in writing code that interfaces directly with IO devices. A
typical DMA operation is described here. Interactions between the main
CPU and DMA device are covered. The impact of DMA on processor's
internal cache is also covered. Processor handling of hardware
interrupts is also described in this section.
Hardware Device Design Pattern
The Hardware Device Design Pattern encapsulates the actual hardware
device being programmed. The main idea is to encapsulate device register
programming and bit manipulation into a single class dealing with the
device.
Very often the lowest level of code that interfaces with the hardware
is difficult to understand and maintain. One of the main reasons for
this is the idiosyncrasies of register level programming model of
hardware devices. Very often devices require registers to be accessed
in a certain sequence. Defining a class to represent the device can go a
long way in simplifying the code by decoupling the low level code and
register manipulation.
New
Section on TCP/IP Networking
Embedded system developers are increasingly working on systems that
interact with the Internet in some way or the other. This makes it
essential to understand the working of TCP/IP and other networking
protocols. Articles in section will describe various protocols as
sequence diagrams.
ICMP - Internet Control Message Protocol
pdf
Ping is a popular application used to check the presence of another
node. Ping uses the ICMP Echo and Echo Reply handshake message for this
purpose. The Echo and Echo Reply messages can be padded with additional
bytes. This feature is used to send pings of different sizes.
Trace Route utility relies on the ICMP Time Exceeded message to trace
the route from the source to the destination. A UDP message with low
time to live (TTL) value is used to trace the route from the source to
destination.
ARP - Address Resolution Protocol pdf
ARP (Address Resolution Protocol) is responsible for mapping from IP
addresses to network specific addressing mechanisms. For example, ARP on
Ethernet provides mapping between 32 bit IP addresses and 48 bit MAC
addresses. ARP is considered to be a low level protocol and it is
generally handled at the device driver level. ARP implementation is
dependent on the underlying network technology. Here we will be
describing an ARP implementation for Ethernet
-- EventHelix.com Team |
