falstaff – yet another tech blog

About

LightScythe is a two meter long stick to draw pictures into the air while taking a photograph using long time expsoure. The two meter stick has LED’s on it which light up to draw the picture column wise.

Aus LightScythe

My LightScythe is based on The Mechatronics Guy‘s implementation. Thanks to him for sharing his idea! This implementation reads the pictures from a USB flash disk and extends the functionality with a remote shutter function for Nikon DSLR cameras and two buttons to select a picture.

Part List

To create a LightScythe you need the following parts

• 2 Meter LED Stripe (http://www.adafruit.com/products/306)
• Arduino/Seeeduino (http://www.seeedstudio.com/depot/seeeduino-v22-atmega-328p-p-669.html)
• VDIP1 (http://www.watterott.com/de/VDIP1)
• A powerful 5V source (I opted to use my 11.1V LiPo with a DC-DC converter)
• LiPo 2650mAh (http://www.hobbyking.com/hobbycity/store/uh_viewItem.asp?idproduct=8915)
• DC-DC converter (http://ch.farnell.com/jsp/search/productdetail.jsp?SKU=1705263)
• High Power IR LED (http://ch.farnell.com/jsp/search/productdetail.jsp?SKU=1779662)
• Some switches, transistors and resistors (see Schema)

Hardware

Aus LightScythe Hardware

You can download my Schema here. The connection of the LightScythe is from ladyada.net.

Software

My LightScythe Software is written using the default Arduino IDE. I’m using some libraries:

• Multi Camera IR Control from Sebastian Setz
• HL1606-LED-Strip-PWM from Limor Fried
• NewSoftSerial from Mikal Hart

You can find the source code of the Arduino Firmware on Github:

https://github.com/falstaff84/LightScythe/

Install the libraries above and download the Firmware from the Github Website using the Download button on the Top-Right side. Unpack the ZIP file to your sketch folder and download the firmware.

Pictures

You can created pictures using any software. But you need to store your picture in a specific Format:

• Filename: Number + “.bmp” (e.g. 1.bmp)
• 4-Bit indexed BMP-File (8-Bit is WIP)
• The pictures need to be rotated counter clockwise by 90°

The rotation is needed because the BMP file format saves the picture column-wise. But the LightScythe Firmware needs the picture row-wise. The CPU would need to much RAM to turn the picture itself, and it would make the firmware also more complicated.

I use a specific Color palette which only contains the color my LightScythe supports. I use GIMP to create the pictures and created a 3-Bit palette. I Usually do the following steps:

1. Create a new Picture (Height 64 Pixel, Width whatever needed)
2. Draw/Paste something
3. Picture => Transformation => 90° Counter Clockwise
4. Picture => Mode => Indexed… => (Import/Choose the LightScythe 3-Bit Color palette)
5. Save the picture as Bitmap file (ending *.bmp)

Copy the picture on a USB flash disk. The flash disk need to be formated with a FAT-Filesystem. You should make sure you don’t have any important files on your USB flash disk! I do not take responsibility for data loss! 🙂