I've been looking at the Raspberry Pi for a number of projects as well, and 
have been running one for a few weeks. 

My take on the early stability concerns/complaints are that the majority of 
those are due to poor power supplies, with some assistance from the Raspberry 
Pi design. 

Measure what you have for DC at TP1 and TP2; it should be close to 5 volts. 

The polyswitch self-resetting fuse on the power input introduces series 
resistance (in the wrong place); on my unit it measures 0.36 ohms (4-wire 
measurement with my HP33401A). Couple this with a cheepie USB supply that's 
already below 5 volts, and you're on thin ice. Do anything that spikes power 
consumption, such as Ethernet, GPU, or plugging in USB devices, and you 
generate more of an IR drop across the polyswitch which can cause erratic 
operation or resets. 

Use a good power supply -- 5 volts at an amp. Adafruit sells one that's 5V/2A 
for under $10. 

Or you can bypass some of the protection components and connect your +5 supply 
to TP1 and TP2. 

Running mine from a solid power source the only problems I've had are with my 
own crummy code... 

Bob K6RTM 

------------------------------ 

Message: 5 
Date: Tue, 16 Oct 2012 15:06:19 -0600 
From: x...@darksmile.net 
To: Discussion of precise time and frequency measurement 
<time-nuts@febo.com> 
Subject: [time-nuts] RasberryPi, timing and GPS receivers 
Message-ID: <20121016150619.16306sbpxvjy8...@darksmile.net> 
Content-Type: text/plain; charset=ISO-8859-1; DelSp="Yes"; 
format="flowed" 

Hello everyone, 

I started a new project for myself where I would use the RasperryPi 
Linux board 
as a NTP server. 

My goal is to design a custom board for the Pi and mount a GPS 
receiver on it. With this combination, I should be able to configure 
NTP for the Pi and thus have the Pi act as a Stratum 1 NTP server. 

The new RasberryPI has 512MB memory so it should be fine for running 
just ntpd. 

Question: What GPS timing module should I go with? No more Motorola 
Oncore so what's best right now? Who sell modules? What are the price 
ranges? 

Your comments are most welcome. 

-George, N2FGX 

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