Von Count is unbearably loud

[DoomHammer]

Something must have changed recently (as in: last few months) because most of the time Von Count's fan is screeching hellishly loud which impacts working conditions in HS.

I see two ways out of this unfortunate state, but maybe there's more:

1. Move the CPU-intensive OpenCV processing out of Von Count and onto a dedicated server. This way Von Count becomes just the image acquisition part, while all the processing happens in a different place. This could also help us scale to having more Counts in different areas of HS. We already have MQTT integration so all we need to do is to send raw image data (ideally encoded/enciphered) instead of the final number.
2. Change the fan threshold somehow probably by utilizing some Balena-related magic that currently only @reinhrst knows about.

To spice up the deal I propose a bounty to whoever delivers this in a satisfiable (ie. quiet) manner: a pizza of your choice from Zajezdnia.

[reinhrst]

😣

I will try to have some time for this soon.

How about option 3, cut one of the wires to the fan 😬

[reinhrst]

Soon as in: definitely not this week.

I then have to see if I have the same hardware here so that I can replicate the problem, else it might be hard to iterate on. From what I remember it's a bit of trial and error.

[badzia]

How about option 4, replace RPi with fan to other device that doesn't need fan but do the same job?

[DoomHammer]

Soon as in: definitely not this week.

I then have to see if I have the same hardware here so that I can replicate the problem, else it might be hard to iterate on. From what I remember it's a bit of trial and error.

Maybe you can share the process and someone else can follow it through?

[DoomHammer]

How about option 4, replace RPi with fan to other device that doesn't need fan but do the same job?

Will it also have such cute case with Count's happy face on it? :D

Sounds good overall, but what would you suggest?

[reinhrst]

There might still be some balena-hacking involved with this latest solution. As I recall I needed some special commands to enable the camera under balena, which may or may not port to new hardware.

One solution may just be a rpi 4, yolov11, and then longer sleeps. In theory that should keep things cool.

(Btw I'm not sure which percentage of the heat comes from the device and which pct from the PoE hat).

[DoomHammer]

Do we have a way to measure that?

[reinhrst]

Feel which chip is warmer 😬

[DoomHammer]

So glad we usually have two hands, will be easier to compare

[reinhrst]

Also good if you burn one....

[reinhrst]

ChatGPT says its all not that hard. I will give it a try

Yes, you're right—when running on BalenaOS, the fan on the Raspberry Pi 3's official PoE HAT tends to kick in at relatively low temperatures (typically around 40–45°C), which can be unnecessarily noisy, especially under light loads. BalenaOS uses a container-based architecture and typically follows the Raspberry Pi OS defaults or its own lower thresholds for thermal management, unless overridden.

Here are a few approaches to manage or reduce the fan noise:

---

✅ 1. Use a Custom Fan Control Script

You can run a container that monitors the CPU temperature and toggles the fan based on your own thresholds.

Steps:

• Disable automatic fan control (see below).
• Add a service to your docker-compose.yml or Balena application that runs a Python or Bash script to control the GPIO pin used by the PoE fan (usually GPIO 14).

Example Python control script:

import RPi.GPIO as GPIO
import time

FAN_PIN = 14
ON_TEMP = 60  # °C
OFF_TEMP = 50  # °C
SLEEP_TIME = 5  # seconds

GPIO.setmode(GPIO.BCM)
GPIO.setup(FAN_PIN, GPIO.OUT)
fan_on = False

def get_temp():
    with open("/sys/class/thermal/thermal_zone0/temp", "r") as f:
        return int(f.read()) / 1000.0

try:
    while True:
        temp = get_temp()
        if temp >= ON_TEMP and not fan_on:
            GPIO.output(FAN_PIN, GPIO.HIGH)
            fan_on = True
        elif temp <= OFF_TEMP and fan_on:
            GPIO.output(FAN_PIN, GPIO.LOW)
            fan_on = False
        time.sleep(SLEEP_TIME)
except KeyboardInterrupt:
    GPIO.cleanup()

🧠 You can modify the ON_TEMP and OFF_TEMP values to suit your noise and cooling preferences.

---

✅ 2. Use Device Tree Overlays to Disable Automatic Fan Control

If BalenaOS is using the default Raspberry Pi device tree overlay for fan control (rpi-poe), it can be disabled or modified.

How to disable automatic control:

1. Go to your Balena dashboard.

2. In your device's config.txt, add:

   dtoverlay=disable-poe-fan
   

3. Reboot the device.

This will stop the kernel from automatically toggling the fan, giving your custom script full control.

---

✅ 3. Use a Quieter Fan or Physical Modifications (if applicable)

If software solutions aren't enough, consider replacing the PoE HAT fan with a quieter model (some users desolder it and install a silent 5V fan), or adding a passive cooling heatsink to reduce the need for active cooling altogether.

---

✅ 4. Switch to Passive Cooling if Load Is Low

If your RPi load is consistently low and thermal headroom is available:

• You might disable the fan entirely (dtoverlay=disable-poe-fan) and rely on heatsinks.
• Regularly monitor CPU temp using vcgencmd measure_temp or cat /sys/class/thermal/thermal_zone0/temp.

---

Let me know if you'd like a full working Balena-compatible container example to handle this.

[DoomHammer]

Am I right to assume that the 1 option looks like the easiest to implement?