Planet HantsLUG

Syndicate content
Planet HantsLUG - http://hantslug.org.uk/planet/
Updated: 46 min 40 sec ago

Philip Stubbs: Arduino and NRF24L01 for Quad-copter build

Thu, 29/01/2015 - 16:28
As part of my Quadcopter build, I am using a couple of Arduino's along with some cheap NRF24L01 from Banggood for the radio transmitter and reciever. The idea came from watching the YouTube channel iforce2d.

When I started developing (copying) the code for the NRF modules, I did a quick search for the required library. For no good reason, I opted for the RadioHead version. Part of my thinking was by using a different library from iforce2d, I would have to poke around in the code a bit more and lean something.

All went well with the initial trials. I managed to get the two modules talking to each other, and even had a simple processing script show the stick outputs by reading from the serial port of the receiver.

Things did not look so good when I plugged the flight controller in. For that I am using an Afro Mini32. With that connected to the computer and Baseflight running, the receiver tab showed a lot of fluctuations on the control signals.

Lots of poking , thinking, and even taking it into work to connect to an oscilloscope, it looked like the radio was mucking up with the timing of the PWM signal for the flight controller. Finally, I decided to give an alternative NRF library a try, and from the Arduino playground site, I selected this one. As per iforce2d, I think.

Well that fixed it. Although, at the same time I cleaned up my code and pulled lots debugging stuff out and changed one if loop to a while loop, so there is a chance that changing the Library was not the answer. Anyhow, it works well now. Just need some more bits to turn up and I can start on the actual copter!
Categories: LUG Community Blogs

Steve Kemp: Recording gym-visits on Linux.

Tue, 27/01/2015 - 00:00

I go to the gym every couple of days. I lift things up, then put them down, and sometimes I repeat this process another 30 times. When I'm done I write down what I've done, how many times I did the lifty-droppy thing, and so on.

I want to see pretty graphs. I want to have records of different things. I guess I just need some simple text-boxes:

deadlift 3 x 7 @ 210lbs.

etc. Sometimes I use machines so I'd say instead:

converging seated-row 3 x 8 @ 150lbs

Anyway that's it. I want a simple GUI, a bit like a spreadsheet where I can easily add rows of each session. (A session might have 10-15 exercises in it, so not many.) I imagine some kind of SQLite database for the back-end. Or CSV. Either works.

Writing GUI software is hard. I guess I should look at GtK or Qt over the next few days and see if it is going to be easier to do it online via a jQuery + CGI system instead. To be honest I expect doing it "online" is liable to be more popular, but I think a desktop toy-application is just as useful.

Categories: LUG Community Blogs

Adam Trickett: Picasa Web: 2015-01-24

Sat, 24/01/2015 - 23:22
Date: 24 Jan 2015
Number of Photos in Album: 1

View Album

Categories: LUG Community Blogs

Philip Stubbs: Quad-copter Build Log - Part 2

Mon, 19/01/2015 - 10:37
Working TransmitterAfter a bit of fiddling, the transmitter works. I have not tested it for range, other than making sure it works across the length of the house. At the moment it only has the standard NRF24L01 module. Although the high-power module has turned up, the antenna for it is still in transit.
As there is still no Quad copter to control, most of the testing has been done by watching numbers scroll up the screen from reading the serial output from the receiver. As this was getting painful, a simple processing script was written to display the control positions on the screen. 
Almost as soon as I started this, I wondered if it would be possible to get the processing script to pass the stick controls onto a flight simulator. A quick look at FlightGear turned into a quick flight around L.A. That is a project for another day.
Flight Control BoardA flight control board has been ordered. I decided on the AfroMini32. This has the usual accelerometers, gyroscopes and a barometer. It also uses a 32 bit micro controller so should be a capable piece of kit. Hopefully it will all come together by the summer.
Categories: LUG Community Blogs

Steve Kemp: Here we go again.

Tue, 06/01/2015 - 00:00

Once upon a time I worked from home for seven years, for a company called Bytemark. Then, due to a variety of reasons, I left. I struck out for adventures and pastures new, enjoyed the novelty of wearing clothes every day, and left the house a bit more often.

Things happened. A year passed.

Now I'm working for Bytemark again, although there are changes and the most obvious one is that I'm working in a shared-space/co-working setup, renting a room in a building near my house instead of being in the house.

Shame I have to get dressed, but otherwise it seems to be OK.

Categories: LUG Community Blogs

Philip Stubbs: Quad-copter Build Log

Mon, 05/01/2015 - 21:06
Having enjoyed watching a series of videos on YouTube, I have been inspired to have a go at building a quad copter. I hope to include here some notes that will act as a reminder for myself. If anybody else decides to try this, please don't rely on this information alone, but please do your research.

RadioThis seems like a good place to start. If this bit can't be made to work, then nothing has been wasted on motors, batteries ESC's etc.
Rather than build an entire transmitter, an old DigiFleet transmitter will be gutted and used for the housing, control sticks, knobs and switches.
I had been hanging onto this transmitter, thinking that I would use it someday, but in the meantime, the NiCAD cells had spilt their guts and pretty much wrecked the circuit boards inside. So nothing was lost by tossing out the control boards, to make space for an Arduino. At the same time, all the parts were removed to give everything a good clean.
Some parts were ordered from Banggood to get started on the radio. An Arduino Pro Mini to use as the reciever, and Arduino Leonardo for the transmitter, and a couple of NRF24L01 boards for the 2.4GHz radio link.

Connecting Arduino to NRF24L01 BoardsAfter receiving the Arduino boards, the first thing was to load new Blink programs. This confirmed that they worked, and I could program them. The only issue was for some reason the Leonardo will only work as root. When it cam to connecting the the NRF modules to the Arduino, it was again the Leonardo that was proved to be more challenging. In addition to the power lines, the NRF's require five extra connections. Three of those connections are not available on the standard header, but are available on the ICSP header. As the remaining two connections can be assigned to any digital pin, it is possible to have all of the Leornardo's 12 analogue input pins free to use. This would make it possible to connect up all the controls on the radio, if needed.

The diagram below shows how the NRF boards were connected for initial testing.

With this set-up, it has been possible to communicate between the boards from different locations in the house.

SoftwareThe YouTube videos that started this mentioned a specific library for the RF modules. For no good reason, for this test, the Radio Head library has been used.
Learnt so far
  • Getting the radios to work was easy.
  • The Leonardo is not quite as simple to use as the pro-mini. Mainly due to the build in USB has to be handled by the Arduino software in a different way.
  • Choosing the Leonardo for the transmitter will allow me to use all 12 analogue inputs.
  • Just because a NRF24L01 board has a plug for an aerial does not mean that it is the high power version!
Categories: LUG Community Blogs

Steve Kemp: Reducing, or redirecting at least, charitable donations.

Tue, 30/12/2014 - 00:00

This is the time of year when there are lots of adverts shown on TV solicating donations for charities, which frequently end with the two words "thank you".

I've always felt there were too many charities in the world, and that it was hard to half-heartedly give money to one charity this month, one the next, and still another next year. On that basis I decided long ago to give my money solely to three charities. If I had money that was spare, or I felt generous that month, I would give it to one of "my" charities. Any other appeals I just ignored (with minor exceptions for one-off events like tsunamis, etc).

I won't claim credit for this idea, it came directly from my mom who does the same thing. I've given money to the same three charities for twenty years now. Maybe not thousands, but hopefully enough to be useful. Certainly more than I'd have given if my donation were split between more recipients.

Now I'm changing. As of next year only one charitable organization will get my pennies. The other two haven't done anything bad, wrong, or failed/succeeded (sadly), but it feels better for me to stick to a single recipient.

Happy Christmas.

(Details shouldn't matter, but to answer the obvious question the charity I've kept is the RNLI.)

Categories: LUG Community Blogs

Martin A. Brooks: Elite Dangerous: Tips for explorers

Sun, 28/12/2014 - 17:45

If you’re not into, or don’t have the equipment to go bounty hunting, exploring in Elite Dangerous can be a lucrative way to make money.  Here are some tips for Commanders wanting to have a go.

You will need a detail scanner which costs CR250,000.  You can explore with just the basic scanner, but it’s much harder.  Assign the scanner to your secondary fire group. It you want to explore deeper space, then you’ll need a fuel scoop, too.   You can get by without a scoop to start with but it means you need to be careful not to stray too far from an inhabited system.  It’s a good idea to keep track of the last inhabited system you were at, if you start to run low on fuel, head back.

Pick a system where there’s no navigation information available, look for the red system information icon in the galaxy map. Systems with an actual name rather than a designation are likely inhabited.

As you jump into the system, whilst still in witchspace, set the throttle to zero. You’re going to arrive very close to the local primary and don’t want to get too hot.  As soon as you exit, press and hold secondary fire to charge the scanner, it takes a few seconds before firing.  The first object you’ll immediately pick up is the star, point the ship at it and hit your “target ahead” key.  You’ll see your ship start scanning it, this takes a little while.  If your detail scanner picks up any other nearby bodies, you’ll get an alert telling you.

Target each unexplored object in turn, working from closest to furthest away.   Anything within 5ls you can scan just by rotating your ship and pointing at it, however at some point you’ll need to start moving around the system.

Be careful near the star, it’s easy to overheat your ship.   If an object is on the other side of the star just point your ship away from the star to get some altitude and, when the heat levels decrease, gradually turn to get the target in your sights.

Learning to jockey the FSD’s autothrottle is essential.  If you keep overshooting objects then you’ll just waste time.  Once the object is in your sights, push the throttle forward until the power line turns blue and leave it there.  Your ship will now automatically accelerate and decelerate for you.  You’ll need to get each object within range to scan, the distance depends on the mass of the object.  Stars can be scanned from a long way out, gas giants from about 100ls, planets from around 20ls or 10ls and rock belts 5ls.

Not all systems contain planets, or they might be out of the range of your detail scanner.  You can try looking round the sky for objects moving relative to the background, I don’t bother and just move on the the next system.

Data you gather can be sold at any station provided you’ve travelled at least 20LY from where you got it.  The least you’ll get is a few hundred credits, however even a single star explored will usually net you around CR1200.   More interesting systems, with high metal content planets, will net you much more.  The highest I’ve seen to date is CR53000.  There seems no point in hoarding the data, the price doesn’t change regardless of distance.

Every so often, seems to be about 1 in 20, you’ll get an interdiction attempt.  It’s up to you whether you fight or flee but if you lose your ship, you will also lose any navigation data you have not sold.  If you get something juicy, it’s probably worth making a deliberate trip to an inhabited system to cash it in.

As you travel around a solar system, you’ll see blips on your scope marked Unidentified Signal Source.  If you investigate these then you may be lucky and it’s free cargo (albeit it will be marked stolen), or it may be dumped toxic waste, or it may be a trap.  The traps are not usually hard to evade if you don’t feel like a fight.  Stolen cargo can be offloaded at the black market, you might have to carry it around for a while before you find one.  I usually limit myself to investigating one USS per system, usually once I’m done with exploring.  If it turns out to be a trap then I just jump to the next system.

 

Categories: LUG Community Blogs

Steve Kemp: Switched to using attic for backups

Fri, 19/12/2014 - 00:00

Even though seeing the word attic reminds me too much of leaking roofs and CVS, I've switched to using the attic backup tool.

I want a simple system which will take incremental backups, perform duplication-elimination (to avoid taking too much space), support encryption, and be fast.

I stopped using backup2l because the .tar.gz files were too annoying, and it was too slow. I started using obnam because I respect Lars and his exceptionally thorough testing-regime, but had to stop using it when things started getting "too slow".

I'll document the usage/installation in the future. For the moment the only annoyance is that it is contained in the Jessie archive, not the Wheezy one. Right now only 2/19 of my hosts are Jessie.

Categories: LUG Community Blogs

Steve Kemp: An anniversary and a retirement

Thu, 11/12/2014 - 10:56

On this day last year I we got married.

This morning my wife cooked me breakfast in bed for the second time in her life, the first being this time last year. In thanks I will cook a three course meal this evening.

 

In unrelated news the BlogSpam service will be retiring the XML/RPC API come 1st January 2015.

This means that any/all plugins which have not been updated to use the JSON API will start to fail.

Fingers crossed nobody will hate me too much..

Categories: LUG Community Blogs

Steve Kemp: I eventually installed Debian on a new desktop.

Sun, 07/12/2014 - 08:12

Recently I build a new desktop system. The hightlights of the hardware are a pair of 512Gb SSDs, which were to be configured in software RAID for additional speed and reliability (I'm paranoid that they'd suddenly stop working one day). From power-on to the (GNOME) login-prompt takes approximately 10 seconds.

I had to fight with the Debian installer to get the beast working though as only the Jessie Beta 2 installer would recognize the SSDs, which are Crucual MX100 devices. My local PXE-setup which deploys the daily testing installer, and the wheezy installer, both failed to recognize the drives at all.

The biggest pain was installing grub on the devices. I think this was mostly this was due to UFI things I didn't understand. I created spare partitions for it, and messaged around with grub-ufi, but ultimately disabled as much of the "fancy modern stuff" as I could in the BIOS, leaving me with AHCI for the SATA SSDs, and then things worked pretty well. After working through the installer about seven times I also simplified things by partitioning and installing on only a single drive, and only configured the RAID once I had a bootable and working system.

(If you've never done that it's pretty fun. Install on one drive. Ignore the other. Then configure the second drive as part of a RAID array, but mark the other half as missing/failed/dead. Once you've done that you can create filesystems on the various /dev/mdX devices, rsync the data across, and once you boot from the system with root=/dev/md2 you can add the first drive as the missing half. Do it patiently and carefully and it'll just work :)

There were some niggles though:

  • Jessie didn't give me the option of the gnome desktop I know/love. So I had to install gnome-session-fallback. I also had to mess around with ~/.config/autostart because the gnome-session-properties command (which should let you tweak the auto-starting applications) doesn't exist anymore.

  • Setting up custom keyboard-shortcuts doesn't seem to work.

  • I had to use gnome-tweak-tool to get icons, etc, on my desktop.

Because I assume the SSDs will just die at some point, and probably both on the same day, I installed and configured obnam to run backups. There is more testing and similar, but this is the core of my backup script:

#!/bin/sh # backup "/" - minus some exceptions. obnam backup -r /media/backups/storage --exclude=/proc --exclude=/sys --exclude=/dev --exclude=/media / # keep files for various periods obnam forget --keep="30d,8w,8m" --repository /media/backups/storage
Categories: LUG Community Blogs