Hub to PC communication

[danielm08097]

I'm trying to get a two way communication system without my non pybricks code on my pc and my pybricks script on my spike prime hub. I know theres already a tutorial online about hub to pc communication but I find it misleading and unhelpful because its not hub to pc but rather pc to hub. So I know how to get my pc to send commands to my hub but I can someone just help me figure out how to get my hub to simply say 'done' or something like that to my pc back. Any help is help, many thanks

[dlech]

The example at https://pybricks.com/projects/tutorials/wireless/hub-to-device/pc-communication/ shows both directions.

On the hub, writing to stdout will send that data to the PC.

[danielm08097]

I'm still struggling to make it work, I've trying to my raspberry pi5 to send a command and destination target for my spike prime automatic warehouse and that data for example A3 like a chess board, gets sent to my pc and to my hub. The motors then move to that location and I want the hub to then send 'done' to my pc which would tell the pc that its ready to receive another destination target from the pi. However the problem I face is that the hub isn't sending the done message to pc or rather the pc isnt receiving it, I'm not sure. I can give you the code, but its quite complicated with 3 different python scripts so I'll just give you the pc and hub one. PC code: https://pastebin.com/axMeqSCe and pybricks hub code: https://pastebin.com/Zc3wnUvc. I understand that its quite long with both being like 100 lines of code but please help if you can, I ask Chatgpt and it gave me this but it still doesn't work. If I had to guess, its always listening to the pi and never listening to the hub so I ask chatgpt if it could fix it and thats what it did but it still doesnt work.

[BertLindeman]

Hi Daniel?

I did not struggle through all of the code lines,
but made a small test program with debugging for the send function:

def send(msg):
    print("try to send", msg)
    try:
        stdout.buffer.write((str(msg) + "\n").encode())
        stdout.flush()
    except Exception as exc:
        print(f"Failed {exc}")
        pass

Run shows:

try to send rdy
Failed 'str' object has no attribute 'encode'

Maybe the reason no data is sent?

Bert

[danielm08097]

Hello Bert, thanks for your help however I'm still struggling to make it work, when I run the code you sent, it says failed 'str' object has no attribute 'encode'. I'm trying to do it over Bluetooth and not with COM ports since the hub never shows up in my device mangers for some reason but with bluetooth, I have to run the pybricks code so that its downloaded onto the hub, disconnect it from the pybricks software (as in disconnect the bluetooth connection to the software) and then run my normal python code on my pc which connects to my hub and then press the button on my hub to start the downloaded code. Am I doing it all correctly? Because my hub never sends messages back and I don't know whats wrong.

[BertLindeman]

Daniel,

1. Maybe I misinterpret your post, but is the syntax error in your hub program fixed?

   At least make sure the syntax error in your hub program is fixed.
   This line is wrong:

   stdout.buffer.write((str(msg) + "\n").encode())

   I did not fix the error, I just showed you this is an error.

2. try / except statements with a pass in the except branch never show an error. These are hard to debug.

3. Maybe you can write a small PC program that only shows the data is coming in?
   That makes debugging a lot easier.

4. The order you show seems correct to me.

Bert

[danielm08097]

Thanks I'll try all of this but with the projects I'm currently working on, I only receive data after I stopped the program with button on the hub and the data I receive is just random gibberish

PS C:\Users\danie\OneDrive\Documents> python pc_ble_control.py
🔍 Scanning for hub...
✅ Found hub: 3B:60:EE:38:F1:10: Yellow Hub
🔗 Connected to hub.
📡 Waiting for Pi on port 5000...
🤝 Connected to Pi: ('192.168.1.156', 53690)
➡️ From Pi: A2
⬅️ Hub: @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@`The program was stopped (SystemExit).

As you can see here it just sends a bunch of @s, if I had to guess is it maybe random binary data being sent that for some reason my computer isn't decoding? Also it looks like I'm receiving that data and then stopping the program however its only when I stop the program where those @ symbols come in, if I never stopped the program the terminal would just stay on 'From Pi: A2' and nothing after that.