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

[Hal Murray]

address@hidden said:
>> I don’t think the issue is that the board designers cut cost -
>>there’s power regulation on the boards.
> I'm sure there is.  But not a lot of it.  Many are the reports of problems
> in the presence of wobbly power - I'd heard a few myself even before I
> started working with these boards. 

The regulators on the Pi provide 3.3V.  The Pi expects the 5V to be close to 
5V.

I think the basic problem is that the USB specs allow a lot lower than 5V and 
the Pi designers didn't leave room for that.

USB spec says:
All hubs and peripheral devices shall be able to provide configuration 
information with as little
as 4.00 V at the device end of their B-series receptacle. Both low and 
high-power devices need
to be operational with this minimum voltage.
Figure 11-5 shows the minimum allowable voltages. Note that under transient 
conditions, the
supply at the device can drop to 3.67 V for a brief moment.

The 24 AWG is a step in the right direction but not good enough if you expect 
5V.


-- 
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