Chris and I did the first Student Robotics “training” lecture yesterday. Not quite as many people turned up as we wanted, but I think it was well received by the people who were there. Hopefully it’ll be the first in a series of sessions that try to fill some of the gaps between undergraduate courses and what Student Robotics needs.
This talk was about how to use subversion, a versioning system. The slides are available here.
Chris and I just finished our presentation about Student Robotics at the Robotics in the Curriculum event. We think it went down pretty well. I’ve made the slides available here.
Ever since Student Robotics began there’s been a monotonically increasing knowledge barrier presented to new university student members. We’ve always tried to ease the assimilation process, but our methods haven’t been too effective. However, Chris is now our president. Chris has been through most of this wall of knowledge, which has put him in a good position to understand some of the issues in becoming a new member — and is thus helping the whole group understand this problem.
In a meeting last academic year we decided that we’d run a few sessions on various bits of stuff that would be useful for new members. The first one that we’re running is about Subversion and is happening on Thursday at 18:00 in seminar room 1, Zepler building. Chris and I are doing this presentation and it should last about an hour including questions.
Chris and I are also doing another presentation on Thursday at the “Robotics in the Curriculum” event. Unfortunately it’s a private event, but it should hopefully help us get the message about Student Robotics out to some people who may be interested in helping us expand the scheme.
Of course, I’m also doing my PhD. I spent today’s PhD hours reading about real and artificial Gecko feet. They’re just witchcraft.
Tom has been around here for the past few days working on the new Student Robotics kit with me. We got to the point where Tom needed to use msp430-gdb so he could debug the firmware for the msp430 on the power board. I’ve previously packaged the compiler, mspgcc, but I hadn’t got around to packaging gdb.
I decided that my time would be better invested if I finished packaging msp430-gdb rather than performing another source install on someone else’s machine. Whilst I was at it, I also packaged msp430-gdbproxy and the udev rule required to get the UIF to work.
Now all the msp430 packages packages are available for Fedora 9:
- msp430-binutils 2.18
- msp430-gcc 3.2.3
- msp430-libc (from CVS on 2008-08-28)
- msp430-gdb 6.8
- msp430-gdbproxy 0.7 (includes udev rule).
You’ll find the specfiles and source RPMs in the same directory.
You can install them all by running:
su -c "rpm -Uvh http://users.ecs.soton.ac.uk/rds/rpm/mspgcc/msp430-binutils-2.18-1.fc9.i386.rpm \ http://users.ecs.soton.ac.uk/rds/rpm/mspgcc/msp430-gcc-3.2.3-1.20080827cvs.fc9.i386.rpm \ http://users.ecs.soton.ac.uk/rds/rpm/mspgcc/msp430-libc-0-1.20080828cvs.fc9.noarch.rpm \ http://users.ecs.soton.ac.uk/rds/rpm/mspgcc/msp430-gdb-6.8-1.fc9.i386.rpm \ http://users.ecs.soton.ac.uk/rds/rpm/mspgcc/msp430-gdbproxy-0.7.1-1.fc9.i386.rpm"
I’m still waiting for someone to review my request to get binutils for msp430 into Fedora. :-/
I present you with Screwfix man:
That’s just under one Screwfix catalogue and about three hours work. Thank you Faye and Joe for helping me with the assembly.
I thought that I’d publish an update on the Student Robotics situation to try and explain to people what’s going on. At the moment, we’re as busy as we can be. SR 2009 has just been kicked off, so there are a lot of people expecting stuff from us at colleges. At the same time, we have to perform recruitment on the University side of things — which we’re just not at all prepared for.
This time last year, we were trying to do the same thing. We were recruiting new people and sorting out college stuff. We didn’t pay enough attention to the new Uni people, and didn’t introduce them enough to the new situation, which lead to almost all the new members not turning up again. This time around we’re trying not to suddenly present members with a massive wall of information that’s really challenging to get through (Chris made it though!), but reduce the learning curve by letting them experience .
Chris and I are working on the website as much as we can at the moment. We are close to releasing the new web-IDE as well. It’s quite stressful, as we’ve got people from 3 sides trying to get us to do things: the colleges, the rest of the SR group and the new SR members who are waiting for their induction session.
The next few weeks are going to be a big grind for us, but hopefully we’ll come out the other side with some awesome.
Because Orcad Capture’s “DSN” files aren’t a free or open format, I’ve converted the beagleboard schematics into a PDF on Uni machines. Enjoy. The PDF file is a derivative work of the files produced by the beagleboard project, and is licensed under a Creative Commons Attribution-Share Alike 3.0 license.
Our house used to have a shed that looked like this:
Jeff and I decided that we needed to upgrade the shed. So we removed the old shed, which we think may have been an Anderson shelter — although it seems to differ a bit from the description on wikipedia. So we chopped it up:
Then we shoved it in Jeff’s car and took it to the dump:
Next came the clearing of the area for the new shed. There was a lot of bits of dead tree and stuff in this area, which we burnt. We wanted to burn these really quickly as we had a lot of stuff to get through — so we raised the fire, in the shopping trolley that we found under a tree in the garden, in order to give it more ventilation. Faye generously leant us her hairdryer, which was then attached to some tubing that we pointed into middle of the fire. This made the fire insanely hot:
(That’s a marshmallow on a stick). Jeff melted some aluminium in the middle of the fire, and then managed to get some steel red hot in it (see the flickr pics). It’s surprising what you can do with a hair dryer and some wood!
Jeff and I were contractually obliged to give Justyn a single unsalted roasted peanut. I won’t go into the details too much here, but there was a bet that involved university wifi and our house. Jeff and I lost, hence the peanut.
Unfortunately, it was difficult to purchase an unsalted roasted peanut from the shops, so I roasted it myself.
My good friends Joe and Lou left for Morocco in a modded Transit van in early July. Since then, they’ve been performing copious amounts of windsurfing and kite surfing and probably some other water-sports that I’m unaware of. They made it to Morocco a while back and are now on their way back. This week they had a guest appearance on their blog.
In the month running up to their departure, Joe worked really hard at modding the interior of his van so that they could sleep and cook in it and store all the equipment they’d need — including windsurf boards, sails, bikes, kites and many more things. It was an impressive feat, and it was finished days before they were due to leave.
Earlier this year, in February I think, I subscribed to fitting a dimmed LED lighting system into the back of the van for Joe. I didn’t actually get around to doing this until about a week before Lou and Joe were due to leave. At this time I was working for ECS and was due to leave for Iceland in a few weeks. Unfortunately, the electronics that we needed to take to Iceland really needed a few more months until I’d certify it as shippable — so I was already working reasonably long hours (the extremely long hours didn’t start until the week before we left for Iceland, but I’ll leave this story to another time) and only had a few hours each evening to work on it. Thus I had to bodge the dimmer together fairly quickly.
The dimmer was an MSP430F2002 connected to two FETs and two pots. The MSP430 used PWM to control the lights. Joe and I put the circuit into wall-mounted dual-knob dimmer switch casing and recycled its pots. I bunged the circuit onto stripboard in an ad-hoc manner and then Joe and I gave it a test in the van. There were two major problems:
- The lights would flicker. Due to the hardware limitations of the chip I was using, the PWM outputs had to be switched on and off by the software from a timer interrupt. I realised that I’d been suffering from a similar problem Alexis and I had before on the SR PWM board, and moved all other functionality out of the interrupt routines so that nothing could add noise to the PWM timing. This mostly solved the problem, but not completely. I think there was quite a lot of noise in the readings from the pots, but I didn’t get to the bottom of this in time. In the end, I added two filters — a moving average and an IIR filter that both acted to low-pass the readings from the pots.
- The MSP430 would brown-out sometimes when the board was initially switched on. This meant that the electricity supply to the back of the van needed power cycling every time this happened (there is a switch on the dashboard). This was really annoying and could have been solved by a reset controller. Unfortunately, I had none.
-
The pots turned out to be non-linear. In my initial investigation of the pots, I’d put my multi-meter across it’s terminals and seen a linear change in resistance. I obviously hadn’t investigated this thoroughly enough, as when I came to fit the pots into the circuit I found that the thing acted non-linearly. On closer examination, the resistance changed linearly between two terminals of the pot and the other two were linked by a fixed resistance. If you do your sums, you’ll find that this results in a non-linear change in output voltage if you just use this thing as a voltage divider.
I went mad. Then Jeff took apart one of the pots. We looked at it. We cried. We scratched off some of the resistive track that formed the fixed resistance. If we could reconnect the now free terminal to one end of the track then we’d be done. After a rather unsuccessful attempt at doing this with a rivet, we gave up on that approach.
If we could get our hands on the innards of a linear pot that was the right size, then maybe everything would turn out alright. We ferreted around in the pots we had lying around. It turned out that a pot that I had from a project we’d been doing about four years ago was exactly the right size. And I had two of them. Perfect. Jeff spent a few of the early hours in the morning cutting away bits of the pot casing to fit the new ones in. Success. The first pot was now linear. Then came the second pot. I was dead at this point, so I went to bed. Something went wrong with the second pot mod. Luckily, Maplin still sell a pot that’s of a compatible size! Joe went there the next day. Problem solved.
Jeff also spent the last few days in the run-up to Lou and Joe’s departure building a dashboard-mounted battery monitor for them. I’m sure he’ll blog about it soon.
Then they left. I heard very little about my precious LED controller for two months. Jeff heard nothing of his battery monitor either. We were worried. Was the electronics working? Lou and Joe were blogging, but about the wrong things! They were talking about wind surfing, kite surfing and camp sites. Were they avoiding blogging about the electronics because it had stopped working? It was great to hear about their progress along the way, but come on guys! Where were the electronics posts?! All Jeff and I could think about whilst we were walking around on an Icelandic glacier was “is the van electronics still working?”*.
So. September began. Jeff decided that he was going to fly out and stay with Joe and Lou for a week. Obviously he chose to do this to find out how the electronics was doing. And pretty soon after his arrival he provided me with an update. Now he’s managed to get the required information into their blog.
And the moral of the story is: if you need to find out about the status of a remote system you’ve put together, send an Engineer. Wait, that’s not entirely connect. Perhaps this is better: If you need to find out about the status of a remote system you’ve put together, sending an Engineer works.
* OK. So that’s not entirely true.
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