Meeting: 13th August 2012 – Raspberry Pi Part 1


  • Topic: Raspberry Pi
  • Host: Hands on
  • I got my Raspberry Pi a while back now and after plugging everything in and creating a bootable SD card stood back and awaited the wonders to unfold, lines and lines of text with most being error messages soon dampened my enthusiasm. I did persevere for an hour or so but with no luck. As the August meeting was due and the talk was on the Pi I decided to give it another go, managed to get Debian Wheezy up and running but it seemed unstable and would constantly crash, Rasbmc and Xbian just seemed to load and then hang up. At the meeting Jon was trying to compile for his Pi and Martin brought his Pi with an industrial grade PSU to boot. After playing around with Martins set up and trying my Pi and setup on his PSU it was clear that the problem lay with my power supply. The next day I went back on several of the Pi forums and watched several Youtube videos on problems relating to the Pi and power, I then dug out my trusty multimeter and started some tests of my own, low and behold the seat of all my problems was revealed very soon. The Pi runs from a 5V supply but has a minimum threshold of 4.7volts, I broke open my USB lead and measured the voltage going into the unit, this measured 5.1V, with everything unplugged from the Pi I checked at TP1 and TP2, the voltage was only 4.7V, as I plugged the HDMI and USB hub in this dropped to 4.5V and the problems showed up immediately, I then dug out a quality power supply but got the exact same results, this lead me to now question the actual lead, even though I had broke into the lead close to the micro USB plug I realised that the actual plug itself must be the source of the power drop, I went out and bought a quality Micro USB lead (Nikkai pure connectivity) and plugged it in, now everything suddenly works, I even used the original power supply that I thought was dodgy, I checked the voltage on the Pi and even with a keyboard and mouse plugged directly into the Pi and not through a USB hub I still get 4.8V. I have read many articles talking about using good power supplies but that is only half the tale, a good cable is just as important and I can now start to enjoy using the Pi and try other things on it. I know I may have gone on a bit but for those who are looking at buying a Pi then ensure you also buy quality cables to suit.
  • Regards USB hubs, Pi’s are also very fussy about which ones they like, I have a Logik LP2HUB10 that works fine, I also have 2 D-Link hubs that work DUB-H4.
  • I have tried Debian Wheezy which seems quite stable and runs well, Rasbmc works OK as does Xbian but both need further development.
  • Now that everything is running fine I am keen to explore other uses, Tim gave me a cool script to get Chrome running on Wheezy but it seemed slow.
  • We said that due to the holidays we would would be looking at another meeting soon covering the Raspberry Pi and I will be keen to see what else can be done with these little gems.
  • Some useful links

Peter Mitchell

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