channel-e information in an electronic age.
Is this the world's first hardware and software upgradable radiator cover?
Back in February 2004 I had to make a radiator cover for Elliot's room. It was going to be a simple project, 6mm MDF sheet with Mexican style geometric shapes cut out of it. But as I thought about it it transformed into a week long electronics project.
The front of the radiator cover is, as planned, 6mm MDF sheet glued and screwed to a frame of (something like) 40mm square timber. This allows for various shapes to be cut from the front. These are backed with fabric or mesh so that the heat can escape. The illuminated shapes (all lit with 5mm LEDs) are listed below (front left and right). There are also twenty yellow 3mm LEDs that give the effect of distant stars. (image)
I used speaker cable for wiring as it's cheapest I could find, though a little heavy for the job. Power is provided by a 5 volt mains transformer.
The timing of the LEDs is controlled by a Microchip PIC16F84 microcontroller. There are two logic chips on the board too, a 74LS154 and a 74LS137. The schematic diagram also gives details of the edge connections from the board to the wiring in the cover itself. The touch sensor was never implemented.
The control program is was written in assembler and compiled used the standard Microchip MPLab application suite. The chip was flashed with a PICStart Plus programmer.
The controller sleeps until INT0 on PORTB is triggered. Note that the LEDs are strobed. The clock speed (approx. 386KHz) was chosen to give the stars a gentle shimmering effect. The watchdog timer is not used, though I may review this in future projects.
The sequence starts when the photo transistor detects a light to dark transition. The first transition causes all the stars and the planet to light. Every few minutes there is a countdown from three followed by the rocket launching. Offset by a minute or so the four LEDs along the side of the UFO flash in sequence and the alien lights up green. After about 12 minutes the stars extinguish. At about 16 minutes the moon lights and a minute later the planet goes dark too. After 20 minutes the system goes back to sleep ready for next time.
Some basic programming is built in. If the bedroom lights are flashed a second time then all but one of the stars extinguish. Another flash turns this star off too. (Another flash brings all of the stars back on.)
The control program is not perfect on this. Sometimes it crashes and stops with various bits lit up. A reset is then required to get it going again. For this reason I will add a reset button on the next one I do. I would also like better sensitivity control of when it switches on. On cloudy days it can switch on as the sun moves in and out of cloud.
I'm on with Imogen's now. It is a Strange Emily theme. Emily sits in the middle, surrounded by three of her cats. The cat eyes fade between green and red. The top and bottom of the cover are lit with red LEDs These strobe in various patterns and can fade in and out. I'm using the watchdog timer on this one, hoping to avoid the need for a reset button. Once I have finished I'll make the code and design available here.
Released under the GNU General Public License. Download or view.
