Deloptes  wrote:
> Chris Green wrote:
>
> > I was talking about pre-4 Pis, they have USB 2 and the specification
> > on that (except for some 'power only' ones, which the Pi's USB isn't)
> > is a maximum of 500mA.  So cables which are perfectly OK for the USB
> > 2.0 specification don't necessarily have to be able to carry the
> > current required by the Pi.
> >
> > I agree that with the advent of USB C/3 on the Pi 4 the Pi is well
> > within the specifications for those cables/interfaces so cables
> > conforming to the specifications should be capable of carrying the
> > required current.
>
> Chris, you are again mixing up things. The one thing is the power supply (we
> are talking about) the other thing is the USB port on the device - here you
> are right it would supply about 0.5A

What we were *actually* talking about was the *cable*.  What I was
originally trying to say was that USB 2.0 *cables* are not rated to
carry the current that the Pi takes.

I said that even a Pi 2 I am running takes more current than many/most
USB 2.0 cables carry without a significant voltage drop.  I found that
only about 1 in 4 cables kept my Pi 2 happy.  The point was that these
cables fulfil the USB 2.0 specification but are not heavy enough to
carry the current a Pi requires.

--
Chris Green
·

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