How to connect to the vcp on computer side

[zhengyunqq]

Very useful docs, thanks for your effort. Cloud you please give an example of how to connect to the vcp，send/read data to/from the vcp on the computer side？

[NStrijbosch]

The script on the computer side can basically be in any programming language that supports serial communication over a COM port. I am most experienced in Matlab, hence my example scripts are in Matlab. Given that not everyone has access to Matlab I did not include these. In the future I may try pySerial and add an example of this. For now you can check out: https://pythonhosted.org/pyserial/shortintro.html

Let me know if this helped you!

[zhengyunqq]

Thanks a lot. I will try and give feedback then. BTW, look forward to the hub2hub lib👍.

[zhengyunqq]

The script on the computer side can basically be in any programming language that supports serial communication over a COM port. I am most experienced in Matlab, hence my example scripts are in Matlab. Given that not everyone has access to Matlab I did not include these. In the future I may try pySerial and add an example of this. For now you can check out: https://pythonhosted.org/pyserial/shortintro.html

Let me know if this helped you!

It works!
The hub side code:

from hub import BT_VCP
com = BT_VCP(0)
while 1: 
    if com.isconnected():
        hub.speaker.beep()
        message = com.recv(4, timeout=400)
        message = str(message.decode('UTF-8'))
        hub.light_matrix.write(message)
        del message

The computer side code:

import serial
ser = serial.Serial('/dev/tty.LEGOHub380B3CADEAB0-Ser')
ser.write(b'5555')

The hub beeps and the light matrix correctly displays 5555.

[NStrijbosch]

Great work! I will test your code soon, and add a similar example for others to get started on a computer side script too.

[zhengyunqq]

Great work! I will test your code soon, and add a similar example for others to get started on a computer side script too.

I met a problem when serial.read() from the computer side.
As the internal hub constantly sends logs like,

b'{"m":0,"p":[[0, []], [0, []], [0, []], [0, []], [0, []], [0, []], [-6, -120, 999], [0, 6, 0], [51, 0, 6], "", 0]}
{"m":0,"p":[[0, []], [0, []], [0, []], [0, []], [0, []], [0, []], [-9, -121, 998], [0, 6, 0], [51, 0, 6], "", 0]}'

the data I sent from the hub side is mixed into above internal hub logs. Do you know how to stop the hub itself send the logs?
Thanks

[NStrijbosch]

The hub indeed constantly sends those messages. If you would connect to the through for example Putty pressing CTRL-C will interrupt these messages from the hub. I believe the command serial.write('\x03') in your script running on the computer will have the same result. Another option that you could try is pressing the left and center button simultaneously to start the hub instead of only the center button.