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Hello,
I recently purchased the MEGA4: 4-Port USB 3.1 PPPS Hub for my Raspberry Pi 4B. I have a specific requirement where I need one of the USB ports to remain off even during and after the Raspberry Pi reboots. Currently, when I turn off a port and reboot the Raspberry Pi, the port automatically turns back on. I'm looking for a solution that not only keeps the port off across reboots but also allows me to reactivate it manually or through a script.
Is there a way to configure the MEGA4 or Raspberry Pi to achieve this? I'm particularly interested in any scripts or commands that can control the power state of the USB ports programmatically. Any help or guidance in this matter would be greatly appreciated.
Thank you!
Posted : 14/01/2024 1:16 pm
There is no such an option to keep specific USB port power off after reboot. However you may consider using an auto-run script that can turn off the port after the boot.
MEGA4's software is a wrapper of uhubctl, so you can call uhubctl command directly.
Posted : 15/01/2024 8:38 am
Hello,
I would like to know if there is any update about this topic which started one year ago. Is there a hope to have a way to power on the Mega4 board with the USB ports off. The problem which makes me leave this board, is when I power on my Raspberry pi 5 and the Mega4 with 3 scanners attached, the Raspberry loops restarting because of lack of power. And this happens before the Raspberry can launch the uhubctl to power off the USB ports. Even with a 15w power supply. It would be so much easier to start with the USB ports off, and then to power them sequentially.
Posted : 10/03/2025 12:23 pm
@alain-arditi 15W power supply is simply not enough for a Raspberry Pi 5 + 3 scanners. The official power supply for Pi5 is 27W.
This situation should really not be taken care of by MEGA4.
Posted : 10/03/2025 2:34 pm
Thanks for your prompt response. But precisely, we want to use a Mega4 to power only one scanner at a time, on demand. Everything works really well except the starting of the Raspberry which need a huge energy call.... For the moment, we use a Big7 + electrical relays + soldering on usb power pins to power USB ports on demand. The Mega4 would do the same without any soldering !
Posted : 10/03/2025 2:58 pm
@alain-arditi the problem here, is the PPPS device (MEGA4) needs to receive PPPS command via USB bus, to turn on/off certain ports. Without properly booting up the USB host (Raspberry Pi), there is no way to send out the correct PPPS command to MEGA4.
PPPS hub is not suitable such work: it doesn't function correctly until the Raspberry Pi is properly booted up.
Posted : 10/03/2025 3:15 pm
Thanks for your answer, it is clear to me !
Posted : 10/03/2025 3:42 pm