I have found many hints mentioning that setting max_usb_current=1 in /boot/config.txt allows USB ports to draw up to 1.2 A

My question is what are other possible values that can be assigned to max_usb_current? if I worte max_usb_current=0.5 does that mean max allowed current is 500 mA? or 1 means logic 1 ?

2 Answers 2


max_usb_current is a boolean.

It is on (1) or off (0).

If set it means let the maximum USB current flow.

  • 2
    The spice must flow! Uhm, the current, I mean the current.
    – Ghanima
    Commented Apr 26, 2016 at 9:29

In the Pi2 and B+ this increases the total USB current across all 4 ports to 1200mA (from 600mA). Each USB port is still limited to 500mA.

It has no effect on the Pi3 (which allows more current by default) and earlier models (which have very low current capacity).

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