XIAO ESP32-C6: CSI streaming does not start automatically on boot

[cledic]

Hello everyone,

I am using a XIAO ESP32-C6 board to experiment with μESPectre and micro-espectre.

I created a main.py file in the root of the flash with the following code:

from src.csi_streamer import stream_csi

def main():
    # Start streaming to the PC
    stream_csi('192.168.1.8', 0)

if __name__ == "__main__":
    main()

My goal is to automatically start CSI data streaming at board boot, so that data can be continuously acquired without keeping the PC connected to the board via serial.

---

❌ Problem

When the board boots and executes main.py, the output is:

============================================================
  CSI UDP Streamer
============================================================
Setting External Antenna... Done!
Connecting to WiFi...
WiFi connected - IP: 192.168.1.5
Chip: ESP32-C6 CSI Optimized with ESP32C6
Traffic generator: 100 pps
Waiting for first CSI frame...
CSI: 64 subcarriers (128 bytes)

Streaming to: {192.168.1.8}:5001
Packet size:  132 bytes
Duration:     infinite

Press Ctrl+C to stop
============================================================

Sent 0 pkts | 0 pps | seq: 0
Sent 0 pkts | 0 pps | seq: 0
Sent 0 pkts | 0 pps | seq: 0
...

No packets are sent, which is also confirmed on the receiving side:

python me collect --label baseline --duration 30
...
❌ No packets received!
...
❌ No samples collected

---

✅ What works

Everything works correctly if I start streaming manually using the me command over serial:

python me stream --ip 192.168.1.8

In this case, packets are sent correctly and received on the PC:

Sent 100 pkts | 96 pps | seq: 100
Sent 200 pkts | 100 pps | seq: 200
...

---

❓ Question

• What am I doing wrong when trying to start streaming automatically from main.py?
• Is there something missing in the initialization sequence when running without the me CLI?
• What is the correct way to always start CSI streaming automatically at board power-on?

Any help or pointers would be greatly appreciated.
Thanks in advance!
Clemente

---

[francescopace]

Ciao Clemente,

I tested your exact code and it works correctly on my ESP32-C6. The auto-start from main.py works fine.
Looking at your output (0 pps), apparently the traffic generator thread is not generating incoming traffic.
Please try this:

1. Let the board boots and executes your main.py

2. In another terminal, ping the ESP32:

   ping -i 0.01 192.168.1.5   # Your ESP32 IP, 100 pings/second

This will generate incoming traffic to the ESP32, which produces a CSI frame for each ping.
If this works, we will need to further investigate the Traffic Generator Thread (there may be some race condition issues).

Let me know if the ping workaround helps.

[cledic]

Ciao Francesco,
I ran the test you suggested, but unfortunately it did not work.

Even when sending a “fast” ping to the ESP32-C6, the streaming output always remains at 0 pps.
Running the same commands manually from the REPL leads to the same result.

The only way I can make it work is by using mpremote.
In fact, from a PowerShell prompt, if I run:

mpremote connect COM31 exec "from src.csi_streamer import stream_csi; stream_csi('192.168.1.8', 0)"

it works correctly and packets are sent.

Honestly, this is quite strange 🙂

Let me know if you have any ideas or if there’s something else I should try.

TIA
Clemente

[cledic]

Quick update that might be useful:

I see the same behavior on a XIAO ESP32-S3 Sense as well.
Streaming starts only when launched via:

mpremote connect COM34 exec "from src.csi_streamer import stream_csi; stream_csi('192.168.1.8', 0)"

If the same code is executed from main.py at boot, or manually from the REPL, the result is always 0 pps.

So this does not seem to be specific to the XIAO ESP32-C6 board.

Clemente

[francescopace]

Hi Clemente,

I hadn’t realized you were on Windows 😅

Jokes aside, the issue might be file encoding or line endings. Windows uses CRLF (\r\n) while Unix/Mac uses LF (\n), and MicroPython can be picky about this.

This would explain why:

• mpremote exec "inline code" → works (code passed as string, not from file)
• main.py created on Windows → doesn't work (wrong line endings)

Please try creating your main.py with Unix line endings:

Option A - Use Notepad++:

• Open your main.py
• Go to Edit → EOL Conversion → Unix (LF)
• Go to Encoding → Convert to UTF-8 (without BOM)
• Save and re-deploy

Option B - Create file directly via mpremote:

mpremote connect COM31 exec "f=open('main.py','w'); f.write('from src.csi_streamer import stream_csi\nstream_csi(\"192.168.1.8\", 0)\n'); f.close()"

Then reset the board.

Let me know if this helps!

[cledic]

Found it!!!

It was not a terminator issue, but rather how I was calling the function.
After looking at your code, I noticed that you were calling stream_csi in a different way.

I changed my main.py from this:

from src.csi_streamer import stream_csi

def main():
    # Start streaming to the PC
    stream_csi('(192.168.1.8)', 0)

if __name__ == "__main__":
    main()

to this:

from src.csi_streamer import stream_csi

def main():
    # Start streaming to the PC
    stream_csi("192.168.1.8", 0)

if __name__ == "__main__":
    main()

And now it works! 🎉

My Python knowledge is quite basic, so honestly I don’t fully understand why calling the function like this:

stream_csi('(192.168.1.8)', 0)

does not work, but at least the root cause is clear now.

Thanks again for the help!

[francescopace]

That's interesting! In Python, single quotes ' and double quotes " are exactly equivalent, so that shouldn't make a difference.

My guess is that you had smart quotes (typographic curly quotes) instead of straight quotes. This can happen if you copy code from Word, email clients, or some websites that auto-convert quotes.

• Wrong: 'text' or "text" (curly/smart quotes - look similar but are different characters!)
• Correct: 'text' or "text" (straight quotes)

Glad it works now!

[cledic]

I ran a few more tests, and this is not a smart quotes issue.

When calling the function as:

stream_csi('(192.168.1.8)', 0)

the IP address passed to stream_csi is actually:

'(192.168.1.8)'

Inside the function, the following variable is defined:

dest_addr = (dest_ip, STREAM_PORT)

which therefore becomes:

('(192.168.1.8)', 5001)

Later in the code handling the UDP send with sock.sendto, I added a print inside the except Exception block and confirmed that an error is always raised in this case:

# Build and send packet
try:
    packet = struct.pack(packet_format, MAGIC_STREAM, num_sc, seq_num, *iq_values)
    sock.sendto(packet, dest_addr)
    packet_count += 1
    seq_num = (seq_num + 1) & 0xFF
except Exception:
    print("sock.sendto ERROR!")
    pass

This is the resulting output, with the error printed and counters staying at zero:

============================================================
  CSI UDP Streamer
============================================================
Setting External Antenna... Done!
Connecting to WiFi...
WiFi connected - IP: 192.168.1.5
Chip: ESP32-C6 CSI Optimized with ESP32C6
Traffic generator: 100 pps
Waiting for first CSI frame...
CSI: 64 subcarriers (128 bytes)

Streaming to: (192.168.1.8):5001
Packet size:  132 bytes
Duration:     infinite

Press Ctrl+C to stop
============================================================

sock.sendto ERROR!
Sent 0 pkts | 0 pps | seq: 0
sock.sendto ERROR!
Sent 0 pkts | 0 pps | seq: 0

So yes — my apologies for the confusion and for wasting your time 🙏
The parentheses simply must not be there in the IP address.

Thanks again for your time and patience!

Best regards
Clemente

[francescopace]

No worries at all, and thanks for the detailed follow-up. It will help others who might face similar issues!