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Re: [gpsd-dev] Field reports from Raspberry Pi GPS HAT users?
From: |
Eric S. Raymond |
Subject: |
Re: [gpsd-dev] Field reports from Raspberry Pi GPS HAT users? |
Date: |
Tue, 19 Apr 2016 00:38:06 -0400 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
Frank Nicholas <address@hidden>:
> The issue is that they made a design decision on the Raspberry Pi 3 that ties
> the serial baud rate to the CPU clock rate (by default).
>
> This was done because the normal lines that fed the serial port were used for
> the built-in Bluetooth.
Well, that would explain a lot. Thanks.
> You have 2 x options - fix the CPU speed at a known, safe speed for serial IO
> to be consistent, or disable BT.
I'll take "Disable the *fuck* out of Bluetooth" for $1200, Alex.
> Most people opt to disable BT. See these posts to disable BT & re-map the
> lines properly to the serial port:
> http://www.briandorey.com/post/Raspberry-Pi-3-UART-Overlay-Workaround
> <http://www.briandorey.com/post/Raspberry-Pi-3-UART-Overlay-Workaround>
> https://openenergymonitor.org/emon/node/12311
> <https://openenergymonitor.org/emon/node/12311>
>
> There is an official Raspberry Pi post, but I couldn’t find it very quickly…
>
> If you look around, you can probably find the post about fixing the CPU clock
> speed also.
>
> Note that this does not affect ANY other Raspberry Pi (A, B, B+, Zero or 2),
> as they do not have built-in BT or WiFi.
Thanks, that was really useful and I think gives us a path forward. I plan
to throw out systemd first.
--
<a href="http://www.catb.org/~esr/">Eric S. Raymond</a>