CAN performance

NETMF & Gadgeteer
1

Hi,

I have tested how fast it’s possible to read CAN data.
The fastest read speed I got on the Embedded Master is 6ms/frame when I send frames at 1ms/frame from CANalyzer.

I need to have at least 1ms/frame in readtime.

Have anyone been able to read faster than 6ms/frame?

2

Are you reading one message or multiple messages from the driver? Can you show some code?

3

I am reading only one message, this to be able to set at timestamp when I recieved the message.


        public LogData Read()
        {
            if (_canHandler.GetRxQueueCount() > 0)
            {
                _splitTime = (int)((DateTime.Now.Ticks - _startTime) / 10000);
                // Timestamp in milliseconds 
                if (_lastTimeStamp != 0)
                    _logData.TimeStamp = _splitTime - _lastTimeStamp;
                else
                    _logData.TimeStamp = 0;

                _lastTimeStamp = _splitTime;

                _canHandler.GetMessages(_canMsgList);
                _logData.Id = _canMsgList[0].ArbID;
                _logData.Length = _canMsgList[0].DLC;
                _logData.Rtr = _canMsgList[0].isRTR;
                _logData.Extended = _canMsgList[0].isEID;

                for (_index = 0; _index < 8; _index++)
                {
                    if (_index < _logData.Length)
                        _logData.Data[_index] = _canMsgList[0].data[_index];
                    else
                        _logData.Data[_index] = 0;
                }
            }
            else
                _logData.Length = 0;

            return _logData;
        }
4

That is why!

TimeStamp is one of the things GHI will add in the new CAN drivers.

Here is a new post and lets get the new CAN drivers ready http://www.tinyclr.com/forum/6/2047/

5

Do you mean that the CAN driver is slow because I read one message at a time?

But even if I read more than one message the buffert in the CAN driver must be able to read more than 1 frame/ms.

I found that the GC mess up the reading alot and timestamp.

6

What you are trying to do has to be done on the driver side. How soon you must have the new CAN drivers?

7

I am evaluating both the USBizi and Vinculum-II chip.

But I like to go for the USBizi because of the NETMF.

So answer to your question: Next week would be great.

8

I’m also waiting (already for a month now) for the new CAN driver before implementing my protocol. I’ll use it on the FEZ Cobra.

9

Does Vinculum compare to USBizi?! Maybe to the raw LPC23xx processor but not USBizi.

We will not have new CAN driver for about 4 weeks but you can use the existing driver for now (with its known limitations). I hope this will not slow you down.

10

In my point of view it’s possible to compare them, they both have hardware driver libraries for CAN and USB host.

Flash update on the “field” and some more equal functions.