4 ms·

You can never trust software to block data flows. There is no such thing as "charge-only" as long as the cable still has data wires in it. > We found that in s

You can never trust software to block data flows. There is no such thing as "charge-only" as long as the cable still has data wires in it. > We found that in some cases the "charge-only" USB mode may also fail to block AT commands.

ForHackernews 8y ago
This is a good point. I wonder if there's a market for "power-only" USB cables without data? Or would those fail to negotiate the right wattage?
- kageurufu 8y ago
  USB-C has separate lines for the "Configuration Channel", that is used to negotiate voltage and amperage. I'm unaware if the specification allows for cables without data lines, but I don't believe they would be required. It would only work on USB-C host devices as well though, USB-A would still revert to either 500mA as long as the data lines are tied with a resistor
- joezydeco 8y ago
  There's the USB Condom: https://int3.cc/products/usbcondoms https://int3.cc/products/usbcondoms http://syncstop.com/ http://syncstop.com/
  - digi_owl 8y ago
    While not at guaranteed, killing the data wires (or shorting them) makes the device think it is dealing with a charge only port. Thus various companies have made devices that conditionally apply said short. Here is one example: https://www.startech.com/Cables/USB-2.0/USB-Adapters/USB-2-Fast-Charging-Adapter~USB2CHADP https://www.startech.com/Cables/USB-2.0/USB-Adapters/USB-2-F...
    - joezydeco 8y ago
      The USB condom is more for situations where you are in public and wish to charge your device from an unknown and possibly hostile USB-A receptacle.
      - DarkStar851 8y ago
        That Startech device still isolates the data line, it just has the added bonus of adding fast charging support. It'd be effective as a "USB condom" alternative.
- c22 8y ago
  I have several cables like this. It's always briefly mystifying when I accidentally grab one to sync some data. No negotiation, my fancy devices just charge at 500mA using these cables.

ForHackernews 8y ago

This is a good point. I wonder if there's a market for "power-only" USB cables without data? Or would those fail to negotiate the right wattage?

kageurufu 8y ago
USB-C has separate lines for the "Configuration Channel", that is used to negotiate voltage and amperage. I'm unaware if the specification allows for cables without data lines, but I don't believe they would be required. It would only work on USB-C host devices as well though, USB-A would still revert to either 500mA as long as the data lines are tied with a resistor
joezydeco 8y ago
There's the USB Condom: https://int3.cc/products/usbcondoms https://int3.cc/products/usbcondoms http://syncstop.com/ http://syncstop.com/
- digi_owl 8y ago
  While not at guaranteed, killing the data wires (or shorting them) makes the device think it is dealing with a charge only port. Thus various companies have made devices that conditionally apply said short. Here is one example: https://www.startech.com/Cables/USB-2.0/USB-Adapters/USB-2-Fast-Charging-Adapter~USB2CHADP https://www.startech.com/Cables/USB-2.0/USB-Adapters/USB-2-F...
  - joezydeco 8y ago
    The USB condom is more for situations where you are in public and wish to charge your device from an unknown and possibly hostile USB-A receptacle.
    - DarkStar851 8y ago
      That Startech device still isolates the data line, it just has the added bonus of adding fast charging support. It'd be effective as a "USB condom" alternative.
c22 8y ago
I have several cables like this. It's always briefly mystifying when I accidentally grab one to sync some data. No negotiation, my fancy devices just charge at 500mA using these cables.