Dec 212012
The Self-resetting Raspberry Pi

Recipe for auto-reset Pi. Take one Rev 2 Raspberry Pi, a few carefully selected slices of fresh Python, one GPIO port (’25 vintage, preferably), one relay (a twin pack is OK, but not AA), one Darlington array (leave the spikes on), a sprinkling of mixed wires and arrange it all carefully with a breadboard. It should end up looking something like this… I decided to take the P6 reset header one step sillier further. Just for fun. ;) The idea here is to use one of the Pi’s own GPIO ports to switch a relay […more…]

Dec 182012
Making a Reset Switch for your Rev 2 Raspberry Pi

One of the changes on the Rev 2 Raspberry Pi board, which I haven’t seen anybody write about yet, (apart from Eben in his original announcement) is the addition of two holes for a header at P6. These were added to enable a reset facility. Shorting those two pins together resets the processor. This was too good an opportunity for my curious mind to pass up, so I decided to add a 2 pin header there and try it out. As luck would have it It just so happened that last week I was given […more…]

Dec 142012
Using a Darlington Array as an inverter for reverse polarity RGB leds

RGB LED RIP :( Last week, I was wiring up a demo with a three colour RGB LED, and accidentally wired the pin for the red component straight to 3V3 (plugged it into the wrong port). It went “crackle” and then turned black. Ooops. Now it’s a GB LED, the red’s a gonner. :( “Dammit. I wanted to shoot a video with the Quick2Wire Interface running the RGB LED. It’s 7pm and if I order some they won’t be here for two days.” “Oh I know. I’ve got an RGB LED in an old Christmas […more…]

Dec 082012
Plan 9 operating system for the Raspberry Pi - demonstration by Richard Miller

There’s not much I can say about this except that it’s tremendously impressive – if you’re a bit of a geek (like me). If you think computers are all about fancy-pants graphics and visual effects, this one might not be for you. ;) Richard Miller demonstrated his recently finished Raspberry Pi port of the Plan 9 operating system at the Oxford Raspberry Jam in November 2012. I caught most of it on film. Plan 9 is a very lightweight and powerful operating system that is written for software developers. I find it very impressive indeed. […more…]

Dec 072012
Quick2Wire Pi Interface Board Beta Review

Quick2Wire Pi Interface (Beta) review The Quick2Wire Pi Interface Board is a new interface board for the Raspberry Pi. It’s not yet released, but it is in Beta. I managed to get hold of one of the Beta kits for research and review. :) I also had a chat with Romilly Cocking, Director of Quick2Wire (more on that at the end).   So, What’s in the kit? 1 PCB 1 Ribbon cable (nice colours) 4 jumpers 11 assorted headers 2 FETs 1 tantalum capacitor 1 LED 1 push button 3V3 voltage regulator 1 diode array […more…]

Nov 302012
Review of ModMyPi case for the Raspberry Pi

I was looking for a Rev 2 Pi, as I wanted one to see if the revision checker function of the Python Gertboard programs worked properly. Farnell was quoting up to 3 weeks lead time, RS are out of stock. :-( Nobody else seemed to have it in stock, but over at ModMyPi, they said they would have some in within a few days. Sold to the man in a hurry :-P It turned out that it was with me within 48 hours, which was excellent. If you buy a Raspberry Pi from ModMyPi you […more…]

Nov 232012
Pi controlled light and fan from mains power socket

Don’t try this unless you know what you are doing. Mains electricity can kill you. Update Since publishing this blog post, I’ve had some feedback about the way I’ve done this and it needs improvements and a redesign to make it safer. Please don’t copy this. I’ve removed some photos so I’m not setting a bad example. Back to the original post Ever since getting my Gertboard in late September, I’ve been thinking about using a Raspberry Pi to switch “proper things”. By “proper things” I mean real, useful, BIG things using mains electricity. :eek: […more…]

Nov 132012
Temperatures, light levels, pressure, logging, LCD, PCB - bringing it all together

Ever since getting the LCD working and temperature and light level logging using COSM and the Pi Cobbler, I’ve wanted to compact all of this onto a single add-on board. I’ve mentioned this in forum posts and other blog articles, but a part of me thought it wouldn’t happen. It took me a few weeks to bring it all together, but it’s finally done and it works :) The circuit I don’t have a full circuit diagram. I may try to put one together later. :) It’s a bit messy but I’ll try to describe […more…]

Nov 072012
How to set up a Barometric pressure sensor BMP085 on Raspberry Pi with Raspbian

Works with Raspbian hf Aug/Sept 2012 Under Pressure From previous blog posts, you’ll know I have a Raspberry Pi set up to read two temperature sensors and two light sensors (inside and outside) and log the data online at COSM Setting up temperature sensors and COSM feed But, as ever, “we want more than that!” So I thought it would be fun to add a barometric pressure sensor. Looking around, it seemed like the BMP085 was a good bet. Even better than that, Adafruit have written Python libraries for it and some setup instructions here. […more…]