SPI mode and bitrate cannot be changed in Arduino DUE

I'm using MATLAB R2016a with Arduino DUE. When a SPI device object is created using spidev, it cannot correctly change SPI mode and bitrate. Mode is alway 0 and bitrate is always 4Mbps. I have tried this also with R2019a and it is the same.

For example, I try to use this command to change Mode to 3 and bitrate to 1Mbps:

spidev(a,'D10','Mode',3,'Bitrate',1000000);

But it does not change anything there.

Is there a bug there? How can it be fixed?

Thanks in advance.

[Andrey Kiselnikov]

Before using the interfaces you should create the system object that will control the board. Can you attach your script here?

Answer 1

[Andrey Kiselnikov]

Right now I have no Arduino Due, but I can check your script next week. If it will be actual, let me know please.

[Massoud Tohidian]

Yes, please do so. I have spent few days struggling with it and couldn’t fix it. Thanks.

[Andrey Kiselnikov]

Hi, I remember what i promised!

>> a = arduino()

a = 

  arduino with properties:

                  Port: 'COM6'
                 Board: 'Due'
         AvailablePins: {'D2-D53', 'A0-A11'}
  AvailableDigitalPins: {'D2-D53', 'A0-A11'}
      AvailablePWMPins: {'D2-D13'}
   AvailableAnalogPins: {'A0-A11'}
    AvailableI2CBusIDs: [0, 1]
             Libraries: {'SPI'}

>> dev = spidev(a,'D10','Mode',3,'Bitrate',1000000)
Warning: Function spidev will be removed. Use device instead.Click here to turn off this warning. 

dev = 

  spidev with properties:

    ChipSelectPin: D10
             Pins: SPI-4(MOSI), SPI-1(MISO), SPI-3(SCK)
             Mode: 3               (0, 1, 2 or 3)
         BitOrder: msbfirst        ('msbfirst' or 'lsbfirst')
          BitRate: 1000000         (Hz)

And...... I'll create an "issue" in MW inner support service to research this bug and properly describe all limitations. If it was useful for you, mark the answer as accepted.

[Massoud Tohidian]

Thanks so much. Please also note that Mode is not properly set to 3, and it is still in Mode 0. In Mode 3 data should be stable at falling edge, not rising.

I appreciate if you could follow it up with Mathworks and post here again any solution you find.

Answer 2

[Massoud Tohidian]

Yes fore sure I have created the system object beforehand. Here is the complete code:

a = arduino()
dev = spidev(a,'D10','Mode',3,'Bitrate',1000000)
writeRead(dev,15);

And it returns this:

a = 
 
arduino with properties:

                    Port: 'COM3'
                   Board: 'Due'
           AvailablePins: {'D2-D53', 'A0-A11'}
               Libraries: {'I2C', 'SPI', 'Servo'}
               
dev = 

  spidev with properties:

    ChipSelectPin: D10
             Pins: SPI-4(MOSI), SPI-1(MISO), SPI-3(SCK)
             Mode: 3               (0, 1, 2 or 3)
         BitOrder: msbfirst        ('msbfirst' or 'lsbfirst')
          BitRate: 1000000     

But in real measured bitrate (on oscilloscope) is still 4Mbps and in Mode 0.

[Andrey Kiselnikov]

"The 'spidev' function is being replaced by the 'device' function, which may perform better in this situation. " Hi, can you try this way?

[Massoud Tohidian]

Both are tried. No difference. I guess something is wrong with Arduino’s Firmware.