USB power management on SL

[Jean-Marc]

Hello everyone,

I have a Lua script reading data from a Linky meter via an FT232 USB-to-serial converter connected to /dev/ttyUSB0.

My script has robust error handling and can detect communication failures, but sometimes the FT232 chip gets "stuck" and a simple USB reset is not sufficient to recover. The chip needs a complete power cycle (5V cut) to restart properly.

Currently I'm using a reset function from user library, but it only does a software USB reset which doesn't cut the 5V power supply.

Question: Is there a way from a Lua script (or system command via os.execute()) to completely cut and restore the 5V power supply to a USB port on the SL?

I've considered:

• uhubctl (if available on SL)
• GPIO control (if USB power is GPIO-controlled)
• SL-specific system commands

Any suggestions or experience with this kind of USB power management on SL?

Thanks in advance!

[Jean-Marc]

Hello everyone,

I have a Lua script reading data from a Linky meter via an FT232 USB-to-serial converter connected to /dev/ttyUSB0.

My script has robust error handling and can detect communication failures, but sometimes the FT232 chip gets "stuck" and a simple USB reset is not sufficient to recover. The chip needs a complete power cycle (5V cut) to restart properly.

Currently I'm using a reset function from user library, but it only does a software USB reset which doesn't cut the 5V power supply.

Question: Is there a way from a Lua script (or system command via os.execute()) to completely cut and restore the 5V power supply to a USB port on the SL?

I've considered:

• uhubctl (if available on SL)
• GPIO control (if USB power is GPIO-controlled)
• SL-specific system commands

Any suggestions or experience with this kind of USB power management on SL?

Thanks in advance!

[Erwin-vd-Zwart]

@Jean-Marc 

You can power cycle USB port like this:

Code:

io.writefile('/dev/usbctrl', 'low')

os.sleep(1)

io.writefile('/dev/usbctrl', 'high')

os.sleep(1)

Make sure that serial port is not open in a script when doing the power cycle. Otherwise the port name might change and script won't work. Also make sure to allow "unsafe scripts" in the general configuration otherwise the io.writefile is not executed.

If this does not work your only option is to fully restart the controller by using os.execute('reboot') but be careful with this, if you loop controller in constant reboot, the only way out of that is a full hardware factory reset, so be sure to have a recent backup before trying this.

[Jean-Marc]

Thanks Erwin,

I already tried the function ('/dev/usb ctrl', 'low') it doesn't work. For now I use the reboot but I don't like this solution at all

 BR

[Jean-Marc]

For those who are interested, here is the solution:

function hardResetUSB()
log("Hard reset USB FT232 - Méthode authorized")

-- Déauthoriser le device USB (coupe la communication)
os.execute('echo "0" > /sys/bus/usb/devices/1-1/authorized')

-- Attendre déconnexion complète
os.execute('sleep 3')

-- Réauthoriser le device USB (reconnecte)
os.execute('echo "1" > /sys/bus/usb/devices/1-1/authorized')

-- Attendre reconnexion et re-création de /dev/ttyUSB0
os.execute('sleep 3')

log("Hard reset USB terminé - FT232 réinitialisé")
end

[Erwin-vd-Zwart]

@Jean-Marc 

Always target the source of the issue instead of putting bandages in place..

I would replace the USB dongle for a better one that probably keeps working..