Archive for the ‘Projects’ Category

Developing a Robot

Monday, August 24th, 2009

The aim of developing this robot is to learn more about low level electronics and practice low-level software engineering, and just to have fun. The technical goal is to have the robot autonomously explore a room and map it out via use of its sensors. Then, after a ‘cold start’ in an unknown position in the room it should be able to locate itself as quicky as possible by identifying the nearest unique features. Much of this challenge comes later at the software stage. For now I am assembling the motor and drive electronics, as well as the ultrasound sensor based radar, IR reflectance sensors and wheel encoder and connecting these to an AVR microprocessor. This microprocessor will present the sensors and actuators to the host PC via an uplink provided by a bluetooth enabled mobile phone.

You can see some images, which I’ll be adding to, here: http://chrishatton.homeip.net/gallery2/main.php?g2_itemId=3093

Retrofitting a Compaq n610c with an SSD Drive

Monday, March 30th, 2009

Retrofit 1. To provide (a jet, automobile, computer, or factory, for example) with parts, devices, or equipment not in existence or available at the time of original manufacture.

I have just finished replacing the mechanical hard disc in my Compaq Evo n610c laptop with a Mtron Mobi 3000 SSD drive. Having used it for just a few hours, I can safely say it was worth it – the increase in responsiveness under Ubuntu Linux is immediately obvious from first boot.

Here is a brief account of the upgrade for the benefit of anyone thinking of doing the same: particularly owners of the Compaq n610 – or laptops of a similar era – which can be given a whole new lease of performance despite being products that are firmly into their middle age…

Never one to make it easy on myself, I bought a 1.8″ ZIF size drive, instead of the standard 2.5″ IDE that the Compaq takes (I was able to find it a fair bit cheaper on eBay). While I realised this woud require a little modification to fit the drive caddy, I han’t anticipated that because of the Compaqs very flimsy caddy design, I would be physically unable to apply the pressure needed to connect the IDE socket deep inside the machine, without there being a full size drive in it.

One bent & twisted caddy later, I downloaded the Compaq Service manual to get straight to the heart of the matter. I would recommend anyone opening their laptop to search for a service manual first; opening a laptop isn’t nearly as obvious and predictable as a desktop machine; they are dense, layered affairs, with clips and screws that need to be removed and replaced in a precise order to avoid snapping or stressing some as yet unrevealed structure. I can’t speak for other manufacturers, but it is to Compaqs credit that they make these manual publicly available.

So, here we go… full access to the hard drive bay required complete disassembly of the laptop, even the screen.

n610_SSD_1

With bay now open, the ZIF drive was put in position. I constructed a crude but effective cradle from slot-together cardboard pieces, there are 3 cardboard ‘ribs’ running under the drive and it is held quite securely in position. The small PCB which I am holding is a ZIF to IDE adapter, to which I have also attached the proprietary socket part of the original caddy. Be careful when attaching a ZIF ribbon cable: the design of the ZIF slots appears to have pins which contact the cable both top and bottom, where in fact only one side is the correct, active orientation. Refer to any guides at hand if you are doing this as one mistake here could cause electrical damage and cost you that lovely new expensive SSD.

n610_SSD_2

The next image shows the underside of the motherboard, held over the bottom half of the laptop case. Only in this position could the ZIF/IDE adapter board be attached to the proprietary hard drive connector on the motherboard. The adapter board is very light and is sufficiently held on by this connector alone.

n610_SSD_3

The motherboard is lowered into position; some last-centimeter-gap poking with a biro is required to persuade the fairly taut ZIF ribbon to flex into the space behind the drive, rather than be fatally crushed between it and the motherboard.

n610_SSD_4

With the motherboard secured back over the bay, the still dismembered laptop is powered up to ensure the drive is compatible, and has a proper electrical connection, before the slightly lengthy process of reassembling the machine. Note the installation of Ubuntu in progress :-)

n610_SSD_5

Performance and other notes to be amended…

Tree2D Applet Online

Monday, February 23rd, 2009

Here is a Java pet project I’ve been working on, partly out of an interest in procedural graphics but mainly just for some good old Java practice and to make the train journeys go a bit faster:

Tree2DApplet

Theres still a number of glaring bugs in the UI code, which I’ll be fixing, but its ready for an idle play. Random feature requests welcome!

The Applet will prompt you to confirm a security certificate since it allows saving of images and vector files to your local hard drive.