MicroCANopen

About the Current Release: V3.30

For many embedded networking applications CAN, the Controller Area Network, is a preferred choice as CAN interfaces are present on microcontrollers from more than 25 different chip manufacturers. However, CAN itself is not sufficient to implement a communication network - a higher-layer protocol is needed to provide pre-defined communication functions. For applications that just use a few nodes and messages, many engineers still tend to develop their own higher-layer protocol, as full protocol stacks like CANopen seem to be an overkill for their application.

What is MicroCANopen?

MicroCANopen is a minimal CANopen implementation targeted at embedded networking applications. To learn more about CANopen, go to CANopen.us. The tutors of ESAcademy implemented MicroCANopen with several goals in mind:

1. Adapt the basics
   MicroCANopen does not aim at 100% CANopen conformance. While it can be made 100% conformant (since V2.00), the primary idea behind MicroCANopen is to simply adapt the minimal set of features that is required to cover standard communication methods and that allow making use of exiting CANopen tools like configurators and analyzers. If the system growths in the future, an upgrade path is already laid out - upgrading to "true" CANopen does not require any changes in the communication channels.
2. Minimal resource requirements
   Full-size CANopen implementations require more resources than some of the latest 8-bit microcontrollers with CAN interface have. On 8051 derivatives, MicroCANopen can fit in as little as 4k of code and about 170 bytes of RAM. Full-featured CANopen implementations often require a multiple of these resources.
3. Minimal learning curve
   MicroCANopen reduces the learning curve for newcomers to CANopen. As advanced features are not implemented, engineers do not need to learn about them immediately.
4. Easy Source Code Configuration
   Since release V3.30 MicroCANopen can include C source files generated by the electronic data sheet editor CANopen Architect EDS. Using this editor, developers can specify the CANopen features and functions required and export C source files for MicroCANopen.
5. Easy Migration to MicroCANopen Plus
   The 'Plus' Version of MicroCANopen includes the most often needed CANopen functions. MicroCANopen Plus is part of our CANopen Magic ProDS Development System.

Implementation

MicroCANopen requires two interfaces.

There is a CAN hardware interface between the CAN controller and the CANopen stack. To keep MicroCANopen simple and portable, this driver has to take care of all microcontroller specific and real-time issues that occur in embedded applications. This includes both timer and CAN interrupt service routines.

The application interface towards the user program provides the functions to initialize the communication and pass on process data back and forth.

Learn more about the interfaces:

• MicroCANopen Hardware Interface
• MicroCANopen Application Interface

Learn more about the implementation

• MicroCANopen Implementation
• MicroCANopen Implementation Examples

Comparison of CANopen with MicroCANopen

Trace window showing the boot-up-sequence of a MicroCANopen Node

Node ID is 3, the heartbeat time is 2.5 seconds and the node has two transmit PDOs using their default (pre-defined) CAN identifiers.

Request MicroCANopen Source Code

Request the free MicroCANopen source code with examples for the NXP LPC2119 and the Atmel T89C51CC01. Once you registered, the distribution file will be emailed to you.

We have an online class explaining MicroCANopen V1.xx and walking through an implementation example. View it now.

Commercial Usage

Although we allow the free download of MicroCANopen the license included is purely an educational license and not for usage in commercial projects.

Support and Feedback

Your feedback is gratefully appreciated. We will consider all suggestions for improving MicroCANopen. For bugs and feedback please send Email to:

Note that due to a high amount of spam email received the link above is not an active link anymore. Please use your email program and hand-type the address into the TO: field to send us an email. We apologize for the inconvenience.

MicroCANopen related publications:

• Entry-level CANopen implementation by ESAcademy,
  Control Engineering
• Approximating CANopen,
  Embedded Systems Programming
• Embedded Networking with MicroMessaging,
  Circuit Cellar
• Embedded Networking with CAN and CANopen,
  Book about the CANbus (Controller Area Network) and CANopen
  RTC Books

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