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© 2007 Microchip Technology Inc. DS01108A-page 1
AN1108
INTRODUCTION
The Microchip TCP/IP Stack with BSD (Berkley Socket
Distribution) Socket API provides the socket library for
Internet TCP/IP communications. The generic socket
programming interface was originally developed by
University of California at Berkeley. Many popular oper-
ating systems such as Microsoft
®
Windows
®
, UNIX
®
,
Linux
®
, eCOS™, and many commercial TCP/IP stacks
support BSD socket API. With a common programming
interface, applications can now be ported easily across
completely different platforms. For example, network
applications written for a PC environment can also be
compiled in an embedded environment, provided the
embedded platform supplies the BSD library API.
This application note describes the Microchip TCP/IP
stack with BSD socket API. It is intended to serve as a
programmer’s reference guide. Topics discussed in this
application note include:
• Creating client/server applications in an
embedded environment
• TCP/IP stack components and design
• Building the stack
• Socket functions included in the API
ASSUMPTION
The author assumes that the reader is familiar with the
Microchip MPLAB
®
IDE, MPLAB
®
REAL ICE™
in-circuit emulator, C programming language, and
socket programming. Terminology from these technol-
ogies is used in this document, and only brief over-
views of the concepts are provided. Advanced users
are encouraged to read the associated specifications.
FEATURES
The TCP/IP Stack with BSD socket API incorporates
these main features:
• Concurrent server support
• Application can be a server or a client, or both
• Optimized for embedded applications
• Full duplex communication
• Stream and datagram socket support
• IP address resolution done in background
• Can be used with or without a kernel/RTOS
LIMITATIONS
The stack is designed for the embedded PIC
®
-based
platform, so there are some inherent limitations associ-
ated with the embedded environment. The limitations
include:
• The socket API implements a subset of the
original BSD socket library.
• The behavior of the API function may differ
slightly from the BSD library.
• All API functions are non-blocking.
SYSTEM HARDWARE
The Microchip TCP/IP stack with BSD socket is devel-
oped on the Microchip Explorer 16 platform. The net-
work chip is a Microchip ENC28J60, a 10 Mbps
integrated MAC/PHY Ethernet controller. The stack can
easily be ported to other PIC microcontrollers. Micro-
chip will release updates of the stack as new PIC
microcontrollers are released.
A block diagram of the Microchip TCP/IP stack with
BSD socket API is presented in Figure 1.
FIGURE 1: MICROCHIP TCP/IP STACK
HARDWARE BLOCK
DIAGRAM
Author: Abdul Rafiq
Microchip Technology Inc.
MAGNETICS
ENC28J60
Ethernet
Controller
SPI
PIC
®
Microcontroller
Microchip TCP/IP Stack with BSD Socket API
