Monday, 30 September 2013
Saturday, 7 September 2013
Yes, this is a different LCD to the one I mentioned previously. I bought two 2.8" cheap and nasty eBay specials and one arrived cracked and the other wouldn't respond to some test code using uTFT. I gave up and decided to buy something a little more professional. Sadly, I seem to have bought the last one RS are ever going to stock. I hope I don't break it.
Anyway, in preparation, I've enabled PLL support and added an option to clock the chip at 66.67MHz. I have a feeling that's going to be helpful later on.
See my github.
Sunday, 25 August 2013
There's so much going on at JP Towers that I feel the need to write some of it down, lest any of it leaks about of my brain.
I've talked about the Jaguar radio upgrade before so that's one.
I'm planning to implement while house temperature monitoring. This will use the cat6 running to (almost) every room and Dallas one-wire temperature sensors. I'll probably drive them as multiple busses using at Arduino as there are issues configuring a star as a single 'bus'. The sensors are in and have been tested on the Arduino, I just need to build an adapter to connect to my patch panel and build some sensor 'plugs' using standard 8P8C shells.
I've got a new boiler going in soon. I've selected a Viessmann 200-W a it has an IR control interface. This will allow me to disable the heating when we're out and restart it on our journey home using my phone. I can probably use the Arduino for this as well as it'll be in roughly the right location anyway.
My brother has fitted a quad-cam Lexus V8 (1UZ-FE) to his Mazda Bongo camper to replace the broken 2.5 diesel. Mechanically it is all fine but issues with the dash and the speed / RPM pickups mean we probably can't use the old dash clocks unchanged. The Lexus tacho needle driver will fit but the frequency of the input needs adjusting to get the numbers correct. For the speedo we've decided it'll simply be easier to fit a TFT where the speedo was and use a Stellaris Launchpad to output speed and odo/trip on the LCD. I did order a couple of cheap TFT modules off eBay - 2.8" units with an ILI 9325 driver and an SD card slot -but one was cracked in transit and neither appear to work at all. RS have something similar, but a bit bigger, so I'll give those a try. I also need to build a circuit to interface the micro with the 12v logic used by the Lexus electrics, but I'm hopeful I can use a standard USB PSU.
Sunday, 21 July 2013
Saturday, 20 July 2013
Well, fast forward a few months and quite a lot of planning, and the second Cambridge Raspberry Jam of 2013 came to Cambridge Consultants.
Mike Horne is the local Raspberry Jam organiser and we're all very grateful to him for arranging these Jams and giving us Pi enthusiasts somewhere to go and talk about what we love. Mike arranged all the ticketing, the demos and the speakers. I arranged with Darina at Cambridge Consultants so we could borrow the reception area, and have teas and coffees and cakes laid on, name badges, etc. Many thanks for Darina for sorting this!
Myself, Mike and our two marshals (Rebecca Hoath and Alan Egan) arrived early to get set up and help those with demos. Thanks to our marshals for coming in to work on their day off and helping make the day a great success.
We kicked off with a brief hello from Mike, followed by an introduction to Cambridge Consultants by Tim Fowler. Tim talked about what Cambridge Consultants do and some of the projects they've worked on in past. These include internet radios, satellite telephones, round tea bags for Tetleys (yes, really) and the ground breaking VideoCore processor which they span out as a company called Alphamosaic. That spin-out was then bought by Broadcom about 9 years ago and it formed the basis of Broadcom's Mobile Multimedia division. That division is, of course, responsible for the Raspberry Pi, which contains a fourth-generation VideoCore processor at its heart.
We had six excellent presentations on the day (including one surprise addition at the end). I'll try and recap them briefly here.
Up first was Ryan Walmsley. Ryan talked about his first year with the Raspberry Pi and listed the many projects he's been working on. You'll most likely know of Ryan through his Rastrack website, which now has 30,000 Raspberry Pi's listed and is registration is included as an option in the standard raspi-config script. He also talked about his efforts getting Raspberry Pi recognised as a valuable distributed computing platform, demonstrating some examples he'd built on the BOINC platform.
Up next was the original Raspberry Pi designer Gert van Loo. Gert gave a really interesting talk on designing electronics for mass production. Did you know, the cost of a small capacitor or resistor is dwarfed by the proportional amount it costs you to hire the pick and place machine for the half-second it takes to lay out the component? For example, if you can get four resistors in a single package but they happen to cost, say 10 times the price, that might not actually be a bad deal because the robot will lay one large part much quicker than four smaller ones. Quicker layout means more boards per hour which means less cost per board. He also talked about the value of adding lots of 'just in case' options to your early designs - although you will of course always forget to add the one you need - and the simple joys of the physical effects you can generate when working with embedded programming. As an embedded engineer, I second that sentiment entirely.
Gert also brought along his son, David, and four Raspberry Pis set up to the audience to try their hand at embedded programming and drive a few Gertboards. This was a very popular activity.
I took the third presentation slot and talked about the work I'd been doing at Cambridge Consultants with the Zoological Society of London (ZSL). We've been building some remote camera traps for wildlife monitoring, but working with the tricky requirement that they had to upload images to the internet in near-realtime, from anywhere on the planet. Oh, and they had to last for ages on a single charge, survive extremes of temperature, submersion in water, angry hyenas, the usual. We've built some prototype cameras using Atmel XMega processors for low power consumption, and linked them with a bespoke wireless protocol to a central node, which houses a Raspberry Pi and an Iridium satellite modem. This modem incidentally, was designed by Cambridge Consultants so we know it inside-out. I was also able to share some pictures of the field trials - undertaken in an actual field at ZSL Whipsnade Zoo!
We then took a break for coffee and cake and everyone had a chance to look around the exhibits in the atrium people had brought along for the day.
Suitably refreshed, we sat back down for our fourth talk, which was given by Boris Adryan. Sticking to our entirely accidental "Embedded Engineering" theme, Boris talked about the trials and tribulations of monitoring the temperature of his wife's greenhouse wirelessly and how he was then able to use the technology at work to diagnose a dodgy refrigeration unit whose demonstrably poor temperature control was causing problems with some of his experiments.
Our fifth and final scheduled speaker was Jim Darby who also continued the embedded theme, by talking about how the Arduino board can be used in conjunction with a Raspberry Pi. Rather than using a slideshow, Jim bravely proceeded to talk through a whole series of live demos, from using a Pi to program an Arduino with a basic 'blinking light' demo, through to his amazing chain of colour changing LEDs, arranged as a 600-bit shift register. Here's a brief video and remember, each of these LEDs is individually controllable, so just about any pattern conceivable is possible:
Our final 'surprise' speaker of the day was High Altitude Balloon hero Dave Ackerman, who regaled us with tails of chasing his balloons across Europe, having sent them up so high they were able to take pictures of the curvature of the earth. Dave also brought along his latest project - a Babbage bear from the Raspberry Pi shop that had been stuffed with a Raspberry Pi, batteries, camera and long-range wireless modem. Babbage hung around the Cambridge Consultants atrium, taking in the view and broadcasting it live to anyone in the area with a suitable receiver.
We then retired to the atrium again to chat and look around some more demos. The event was so popular, people stayed around for over an hour past the official closing time. It's just too much fun talking to like minded individuals about all the projects we either have undertaken or want to undertake next!
I was very grateful that Eben and Liz Upton could join us on the day and I know many of the jammers were very excited to meet them in person.
Here are a few more pictures from the day.
I'm looking forward to the next Jam already!
Saturday, 9 February 2013
The linker script has become more complicated, but I've tried to explain what (I think) it all does.
Saturday, 22 December 2012
The example software bundle is over 340MB and requires signing up for an account, along with requesting 'permission' to see the code. The drivers seem to be BSD licensed, but the example programs cannot be redistributed. I also tried to get the popular 'Code Sourcery' GCC compiler they recommend but all I got was login screens and talk of professional versions.
On Github you will find my solution. You can use either the ARM Linux toolchain in the Ubuntu repostories (yes, even for bare-metal programming) or fetch the one built by ARM. No click throughs. No legalese. Just free software. The bits I wrote are even under the MIT license so you can crib away, guilt-free.
So far, the example flashes an LED and changes the colour if you press either of the buttons. I think I'll build up a simple library for GPIO and UART because, you know, that stuff's fun.
Thanks to http://eehusky.wordpress.com/, http://scompoprojects.wordpress.com/ and http://recursive-labs.com/ who gave me some great pointers (although I've used the mildly-insane SCons build system rather than the deeply-insane and incomprehensible Make).