Waveforms CAN bus

[jma_1]

I am new to the WaveForms software.  In browsing the protocol section, it lists CAN.  I'm happy and surprised to see this feature.  

How is this intended to be used?  For example, using an external CAN bus transceiver to DIO 0 and DIO 1?  A two wire CAN bus is a differential signal (similar to RS485) with clear limits on dominant / recessive states.   

 

I am using the Analog Discovery 2 hardware.  What are the recommended connections? 

I'm hoping any responses to this will also apply to the logic analyzer as well.  Having a CAN bus decoder would be awesome.  

 

WaveForms:

3.8.2 64 bit; Qt 5.6.3; Windows 7

Hardware:

Analog Discover 2

 

Cheers,

JMA

[Piotr Rzeszut]

You have to connect a CAN transceiver to the AD2 to provide a physical layer.

[attila]

Hi @jma_1

In case your CAN signal logic level is suitable (0/3.3V with 1.5V logic threshold) you could also connect it directly or using series resistor to the digital IOs.
For Analog Discovery you need series resistor to limit the sink current by the protection of Digital IOs, for signals above 3.3V
For Digital Discovery for signals above 5V.

Here PModCAN is controlled using SPI commands from Protocol tool, using DIO 0-3
The CAN Low signal is driven by 0/2.5V logic levels, see the Scope capture, so we can connect this safely to DIO.
You can see in the Logic Analyzer the last SPI command and the decoded CAN low signal on DIO 7

[jma_1]

Awesome - thank you for the responses.   

 

Cheers,

JMA

[usermacn]

On 9/18/2018 at 4:43 PM, attila said:

Hi @jma_1

In case your CAN signal logic level is suitable (0/3.3V with 1.5V logic threshold) you could also connect it directly or using series resistor to the digital IOs.
For Analog Discovery you need series resistor to limit the sink current by the protection of Digital IOs, for signals above 3.3V
For Digital Discovery for signals above 5V.

Here PModCAN is controlled using SPI commands from Protocol tool, using DIO 0-3
The CAN Low signal is driven by 0/2.5V logic levels, see the Scope capture, so we can connect this safely to DIO.
You can see in the Logic Analyzer the last SPI command and the decoded CAN low signal on DIO 7

What if I wanted to use the CAN interface to communicate with a vehicle?