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

[Gary E. Miller]

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
$6:

http://www.newegg.com/Product/Product.aspx?Item=9SIAASP40K5443&cm_re=usb_voltmeter-_-0AF-001N-000C6-_-Product

One that computes Watts and WattHours is under $9:

http://www.newegg.com/Product/Product.aspx?Item=9SIA7BF34D5523&cm_re=usb_voltmeter-_-9SIA7BF34D5523-_-Product

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

RGDS
GARY
---------------------------------------------------------------------------
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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