Microchip Technology MA330018 Data Sheet

DS70291G-page  254

© 2007-2012 Microchip Technology Inc.

The ECAN module transmits various types of frames 
which include data messages, or remote transmission 
requests initiated by the user, as other frames that are 
automatically generated for control purposes. The 
following frame types are supported:
• Standard Data Frame:

A standard data frame is generated by a node when 
the node wishes to transmit data. It includes an 11-bit 
Standard Identifier (SID), but not an 18-bit Extended 
Identifier (EID).

• Extended Data Frame:
• An extended data frame is similar to a standard 

data frame, but includes an extended identifier as 
well.

• Remote Frame:
• It is possible for a destination node to request the 

data from the source. For this purpose, the 
destination node sends a remote frame with an 
identifier that matches the identifier of the 
required data frame. The appropriate data source 
node sends a data frame as a response to this 
remote request.

• Error Frame:
• An error frame is generated by any node that 

detects a bus error. An error frame consists of two 
fields: an error flag field and an error delimiter 
field. 

• Overload Frame: 
• An overload frame can be generated by a node as 

a result of two conditions. First, the node detects a 
dominant bit during interframe space which is an 
illegal condition. Second, due to internal condi-
tions, the node is not yet able to start reception of 
the next message. A node can generate a maxi-
mum of 2 sequential overload frames to delay the 
start of the next message.

• Interframe Space:
• Interframe space separates a proceeding frame 

(of whatever type) from a following data or remote 
frame.