Q: We just purchased the Komodo^™ CAN Duo Interface and CAN / I2C Activity Board Pro, and we're using Komodo GUI Software. Everything seems OK when we connect the CAN / I2C Activity Board to the Komodo CAN Duo Interface.

However, when connecting our development board to the activity board without the Komodo, there is a "flood" of CAN messages that makes is difficult to debug our development board software. What we have noticed:

• The activity board constantly transmits CAN messages (0x3A w/data 0x04). It appears that without the Komodo, the activity board is not receiving an ACK and thus runs continuously, retransmitting the same message.
• The PCA  IC for the joystick is OK, nothing is stuck high or low, which usually causes such behavior.

How do we correct this behavior - the activity board continuously transmitting when the Komodo is not attached?

Thanks for your question! Based on your description, the CAN/I2C Activity Board Pro is functioning normally.  The activity board is a great accessory for developers as it has multiple sensors and devices: a 3-axis accelerometer, light sensor, joystick, LEDs, and more.  Most likely, the CAN bus is pinging the sensors on the board, causing the sensors to broadcast their data continuously.

Our recommendation is to filter the data: only view what is needed from the protocol analyzer function of the Komodo interface.  The Komodo GUI Software provides an easy-to-use interface. However, for detailed, real-time analysis of bus transactions, we recommend using the Data Center^TM Software, which provides real-time analysis for monitoring CAN, as well as USB, I2C and SPI protocols.

With the Data Center software set to CAN mode, the CAN bus can be monitored without intrusion. Search fields in the Navigator pane can be set to filter data by ID, Data Length Code, and other metrics.  This setup allows focusing the analysis on a particular CAN node, or even a specific data pattern.  This should provide more visibility to the bus activity and provide more effective troubleshooting information to help identify bugs in your CAN application.

Figure 1: Data Center Software

For more details about using the Komodo CAN Duo Interface, as well as Data Center Software and the CAN / I2C Activity Board Pro, please refer to the following documents: