Adding a GPS Module (hat/shield) on a Raspberry Pi

[Mori Hiroki]

Hi

I use GPS module on RT3050(mips).

I consider solution at serial port for not conflict u-boot.

https://translate.google.com/translate?sl=ja&tl=en&js=y&prev=_t&hl=ja&ie=UTF-8&u=https%3A%2F%2Fqiita.com%2Fyamori813%2Fitems%2F54d6b1a8b7d0e3be6c07&edit-text=


----- Original Message -----
> From: Shamim Shahriar <shamim.shahriar at gmail.com>
> To: freebsd-arm at freebsd.org
> Cc: 
> Date: 2018/2/3, Sat 20:15
> Subject: Adding a GPS Module (hat/shield) on a Raspberry Pi
> 
>G ood morning all
> 
> I had been searching for a solution for the last 3 days, and tried various 
> different things based on the google results, but so far no luck. Hope someone 
> from the list can shed some light and maybe point me to the correct direction.
> 
> Here is the scenario:
> 
> Device: Raspberry Pi B (pi 1 model b, the 512M RAM version, or more precisely 
> v1.2)
> GPS Module : Ublox hat that sits perfectly on the Pi, with PPS on GPIO-18
> FreeBSD version: 11.1 RELEASE for RPI-B
> 
> As I understand, the serial ports on the GPIO is activated by default, and if I 
> attach "ONLY" a serial console (USB to serial), I can interact with 
> the Pi through the console. Remove serial console cable, attach the Pi to a 
> display (via HDMI), boot it up -- it works just fine.
> 
> If now I add the GPS module/hat/shield, all I get is series of dots (depending 
> on how soon the GPS finds the satellites and starts sending the data) and the Pi 
> does not boot at all.
> 
> Based on
> https://forums.freebsd.org/threads/59485/
> https://lists.freebsd.org/pipermail/freebsd-arm/2017-March/015845.html
> https://vzaigrin.wordpress.com/2014/12/13/liberation-of-the-serial-console-in-the-freebsd-on-the-raspberry-pi/
> 
> I have managed to get to the point where I can see that if I have only the 
> serial console cable attached, it stops interacting with the boot process after 
> a while (the boot continues, and I can see that on the HDMI output). But that 
> also stops interacting with whatever signal is being sent via that console).
> 
> And if I attach the GPS module now, it refuses to boot and drops me to a 
> loader> prompt
> 
> My understanding (and I might be very very wrong) is, the u-Boot system is now 
> being affected and hence cannot boot.
> 
> I am not new to FreeBSD, had been using it since the 4.4BSD Lite days, but I am 
> seriously baffled by how difficult (nearly impossible) it had been to get rid of 
> the serial console (something so easy and taken for granted on the i386 or other 
> similar architecture). One of the links I found 
> (https://www.cryptomonkeys.com/2014/01/freebsd-raspberry-pi-gps-ntp/) even 
> suggested that I need to create custom image to get PPS working. Well, working 
> PPS comes *after* being able to boot the device with the GPS hat/module/shield 
> on -- and I am still stuck at that level.
> 
> Any help/pointer/suggestion/direction in this respect is greatly appreciated.
> 
> Best regards
> 
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