资料介绍
Advances in data communications have created
efficient methods for several devices to communicate
over a minimum number of system wires. The
Controller Area Network (CAN) is one of these
methods. CAN sends and receives messages over a
two-wire CAN bus. The nodes broadcast their
individual messages over the CAN bus. Meanwhile, the
receivers are set up to accept the message and
anticipate an Acknowledgment (ACK) signal, indicating
the receipt of a non-corrupted message. The protocol
of the CAN has two states and the bits are either
dominant (logic ‘0’) or recessive (logic ‘ 1’). Nodes may
attempt to transmit a message at the same time. To
ensure that collisions do not reduce the throughput of
the bus, there is an arbitration scheme. In this scheme,
a node will continue to transmit until a dominant bit is
detected, while that node is expecting a recessive bit
(in the ID field) on the CAN bus. The node(s) that lost
arbitration will automatically terminate their transmis-
sion and switch to Receive mode. After the CAN bus
enters an Idle state, these nodes attempt to retransmit.
If the node did not lose arbitration, it completes its
transmission. (For additional information on the CAN
protocol, refer to AN713, “Controller Area Network
( CAN) Basics”, DS00713.)
The bus configuration operates by the multi-master
principle, and allows several Node Boards to connect
directly to the bus. If one Node Board fails in the
system, the other Node Boards are not affected. The
probability of the entire network failing is extremely low
compared to ring type networks. Ring type networks
have a high probability failure rate, due to the fact that
if one node malfunctions, the entire network becomes
inoperable. The CAN controller seeks to solve this
problem. AN212
Smart Sensor CAN Node Using the MCP2515 and PIC16F876
MODULE OVERVIEW
Author: Mike Stanczyk
Diversified Engineering, Inc. The module hardware can be divided into two
components. These are:
CAN-NET Node Board
INTRODUCTION CAN-NET Analog Input Board
Advances in data communications have created These boards can be purchased from Diversified
efficient methods for several devices to communicate Eng
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