User manual

PicoScope 6 User's Guide 177
Copyright © 2007-2013 Pico Technology Ltd. All rights reserved. psw.en r32
9.6
Serial protocols
The serial decoding feature of PicoScope understands the following serial protocols.
9.6.1
CAN protocol
You can decode CAN Bus data using the serial decoding feature built into PicoScope.
About CAN Bus
CAN (Controller Area Network) Bus is a serial protocol used in automotive and
industrial machinery to allow microcontrollers to communicate with each other. The
standard was originally developed in 1983 by Robert Bosch GmbH. It typically uses
differential signalling (with signals named CAN H and CAN L) to increase noise
immunity.
The in-window view of the data looks like this:
The columns in the data table are as follows:
Column
Description
No.
Serial number of the frame (decimal). If Accumulate mode is off,
this counts from the start of the selected waveform. If Accumulate
mode is on, this counts from the start of the first waveform in the
waveform buffer.
ID
Identifier (hexadecimal). Should be unique for a specified data
type. Base frames have an 11-bit identifier, and extended frames
have a 29-bit identifier.
Frame
CAN Bus data is divided into frames, each consisting of a
number of bits. A frame can be any of the following types:
Data: contains data destined for a node
Remote: a request for the transmission of a specific identifier
Error: transmitted by a node that detects an error
Overload: inserted to add a delay between frames
Interframe: time interval preceding data frames and remote
frames
Any frame can also be a base frame or an extended frame.
RTR
Remote transmission request
SRR
Used only in extended frames
IDE
Identifier extension bit