[gpsd-dev] GR-701W hangs on Pi-3

Gary E. Miller gem at rellim.com
Thu Jun 2 19:57:27 UTC 2016

Yo Oliver!

On Thu, 2 Jun 2016 12:00:07 +0100
Oliver Jowett <oliver at mutability.co.uk> wrote:

> On 2 June 2016 at 11:25, Hal Murray <hmurray at megapathdsl.net> wrote:
> > > I just swapped the 701 on a Pi-3 with a 601 on a Pi-2.  
> >
> > That didn't take long.  The 601 just hung on the Pi-3.

I have had no issues with a GR-601W on my Gentoo/Pi3

> Do you trust your power? The Pi 3 is even more picky than the Pi 2.

The Pi people say 2 amps is not good enough, they recommend 2.5A.

I have a USB Volt/Amp meter on my Pi3, never seen it pull more
than 700 mA while compiling a kernel, and running gpsd, ntpd and the
GR-601W.  But no keyboard, mouse or HAT.  Soon to have a HAT.

Unless your USB cable is real short (1 foot, or less) you also need
20AWG USB cables.  700mA can cause a large voltage drop on a thin USB
cable There are a lot of really bad USB cables on the market.

28AWG is 0.064 ohms per foot.  Double that for out and back to 0.128
ohms/ft of USB cable.

Anecdotally, the Pi3 need 4.8V minimum to run.  That means with a stiff
power supply your USB 28AWG can be no longer than 2 feet.  Shorter with
a mouse, keyboard, etc.

Everyone should have a USB V/A meter, they are cheap.  Here is one for


One that computes Watts and WattHours is under $9:


Just be sure your meter can do 9V for the new Quick Charge standard.

Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem at rellim.com  Tel:+1 541 382 8588
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