Overview

A friend asked me if I could turn a damaged samsung LED TV into a coffee table, so I created this project. The TV was damaged in the Christchurch Earthquake a year or so ago, but only the front LCD panel was damaged. The backlight was still intact, so the TV made a really nice coffee table!

Disassembly

The first task was to disassemble the panel, which wasn't too hard to do. The circuitry was separated into the Power Supply and Computer board, and it turns out the Computer board isn't necessary to control the backlight.

Disassembled Panel

The next thing to do was to figure out how to control the backlight. After some experimentation shorting out various wires, I figured out how to turn on the PSU and LEDs.

It turns out the backlight is separated into 4 rows of LEDs, and I realised I could make some really cool patterns! You can see two of the rows active in one of the photos above.

Once I had figured out how to drive it, I started prototyping a circuit.

Electronics

I decided to use a dsPIC30F because I had one on hand, and I didn't want to waste one of my more powerful dsPIC33F chips. The project greatly benefited from the extra power, since it allowed me to have 4x 10 bit PWM channels. (much better than an Arduino!)

Prototype Circuit

Firmware

The firmware supports 4 animation channels, and a brightness channel. 

To make sure the animations look as smooth as possible, I used gamma correction to make it appear linear, and 10 bit PWM to give the widest dynamic range possible.

I discovered at 8 bits, the resolution of animations at low brightness was very poor, especially since I had applied gamma correction. After expanding it to 10 bit resolution, the animations were very nice.

I used inline assembly in parts to make use of the dsPIC instruction set. While not necessary, I wanted to learn it.

There are 8 modes that I added:

1. Fully on
2. Middle rows on
3. Outer rows on
4. Animated waves, from inner to outer rows
5. Animated waves, from one side to the other
6. Pulsing animation, varies from half to full brightness, kind of like a heartbeat 7. Slow flash mode
7. Fast flash mode (aka. Seizure mode!)

The screen is really really bright at full brightness, and it's very weird to look at since it's spread over such a large surface.

I am happy to provide source code on request!

Hardware

After I had gotten the firmware working how I wanted it to, I built a rough frame using spare lumber. It's a little rough around the edges, but it's not bad for a first try!

DIY Wood Frame

Final Product

All that was left was to add some buttons and mount it into its frame:

Sorry, no video of the animations yet.

I recently ordered some PIC24F32KA302 microcontrollers, but found out that my PicKit 2 wouldn't detect them!

Luckily, I found a way to add them to the software. First you need to download the PicKit 2 Device File Editor.

Open the PicKit 2 device file, usually located at
C:\Program Files\Microchip\PicKit 2\PK2DeviceFile.dat

I started by duplicating a similar device, the PIC24F16KA102. Most of the settings appear to be the same for that particular family, so by looking at the differences you can work out what needs to be modified.

But where do you get the missing numbers from? Eventually I stumbled across a datasheet by Microchip: PIC24FXXKA1XX/FVXXKA3XX Flash Programming Specifications

The fields that need to be updated are:

• PartName
• DeviceID
• ProgramMem

All the other fields appear to be the same.

Device ID

The Device ID is in Section 6 near the bottom, and for the PIC24F32KA302 it is 0x4502.

ProgramMem

The Program Memory Size is a little trickier. For example, the PIC24F08 family reports 0x0B00 in the device file, but 0x2BFE in the datasheet. I found the formula to be (0x2BFE + 2) / 2.

Thus for the PIC24F32KA302, the program memory field should be set to 0x2C00

Programming

Save the data file to the desktop, then copy & replace the original.

Now start PicKit 2, select PIC24 from the Device Family menu, and...

Success!

Overview

I recently ordered two RFM23BP radio modules, which transmit at 434MHz. They have a built in amplifier that can produce a 0dBW (1000mW) signal, so I'm hoping that they can reach a few km or so.

Because I live in New Zealand, I have to conform to the radio standards, and thus I decided that it would be better to operate on the 458MHz band where I'm allowed a maximum of -3dBW (500mW).

The RFM23 module supports three modulation modes: OOK (On-Off Keying), FSK (Frequency Shift Keying), and GFSK (Gaussian Frequency Shift Keying). I wanted to know what these modulation modes looked like, so I pulled out my handy RTL-SDR compatible dongle:

458MHz Spectrum

This is the total viewable bandwidth around the 458 MHz band. The red line is centered on that band, and the maximum allowable bandwidth around the band is 70kHz (Contrasted with a total viewable bandwidth of approx 2MHz)

You can also see a strong signal on the left, which appears to be some sort of coded signal.  The faint bands on each side are just artefacts.

OOK

OOK Modulation

The first mode I tried is OOK, where the signal is simply turned on and off to code the data. You can see faint bands on either side of the signal, this is spectral splatter from the sharp signal.

Unlike the next two modes, OOK operates at only one frequency, at 458.58MHz.

FSK

FSK Modulation

The next mode I tried was FSK, where the coded data switches between two frequencies on either side of the center frequency. As with the OOK modulation, there is unwanted spectral splatter on each frequency band, though not as visible here.

Incidentally, the bandwidth of 50kHz is just within the allowable frequency band for 458MHz.

GFSK

GFSK Modulation

GFSK is the module's most efficient mode, as it reduces spectral splatter.  As you can see, it spreads the frequencies out using some sort of gaussian function, which reduces the harshness of the signal.

Footnote

The above screenshots were captured without an antenna on the RFM23 module, with the power level set to only 1.3mW! So obviously it will have very good range once I add a proper antenna.

My next task will be to test the maximum range of this module, and hopefully it will extend far enough for my needs!

Overview

For Year 13 Graphics & Design, we were tasked to find a real client and design a project for them. My clients were my parents, who wanted to build a house on an empty section they have.

The project took a whole year, and I went through research, concept development, and numerous meetings to figure out what my clients wanted.

It was a great project, and these renders show the result of all my hard work!

Concepts

Renders

Screenshots

© Jared Sanson 2009