More E-TTL info from Bill

As mentioned in a previous post, Bill Grundmann has been documenting his investigation into Canons E-TTL protocol.  Bill has just released a PDF summarising what he has found so far.

I’ve yet to go over it in detail, but for those looking at doing some E-TTL investigation of their own this document is a must.

http://billgrundmann.files.wordpress.com/2009/03/ettl_grundmann.pdf

Firmware

Firmware Details:

At the moment it’s pretty basic, but works!  Source is available via SVN (see download page)

The mode is set at powerup by pressing the manual trigger button. If pressed then mode is set to Master, default powerup is in slave mode (i.e.. do nothing). Master mode is identified by a single flash of the LED, Slave is a double flash. This way any of the units can be master or a slave.

Master mode sends a remote trigger command to the slaves when the manual trigger button is pressed, or a trigger signal is detected on the Trigger Input. The LED is light briefly when triggered.

Slaves will only trigger the local strobe if trigger test button is pressed, or a remote trigger command is received via RF. The status LED will light briefly when triggered by either of these means.

The Master will send out a keep-alive broadcast once every 5 seconds. The units LED (master and slaves) will blink briefly to indicated successful RF Link.

Back-Prototype Triggr Home Next – Protocol Details

StrobIt Triggr

Introduction

20/03/09 *UPDATE * This project now has a new home and is actively being developed on Google code project hosting http://code.google.com/p/strobit/

IMPORTANT    This page is no longer being being maintained please go to the new project page.

Welcome to the Strobit Triggr Project, an open source hackable wireless trigger used in photography lighting by using low cost strobe units triggered remotely via RF. This was started while trying to find a cost effective and reliable solution to the commercial alternatives out there. At one end of the market is the Ebay or Cactus Trigger, which is low cost but rather unreliable. At the other end of the market there is the industry standard, Pocket Wizards, very reliable, but very expensive (i.e. way out of my price range).

What I wanted to do was to create an open platform that anyone can easily build for a low cost and then be expand upon by the community. The pair of prototypes I’ve built were a proof of concept that I can get a camera to trigger a strobe unit reliably at a low cost. From early tests it appears that I’ve succeeded in my goal, but further testing is required.

triggr0103

Project Status :

– Prototype successfully working in single master/slave configuration !

– (20/03/2009) Project now has a home at Google Code – http://code.google.com/p/strobit/

Still Todo:

  • Specifications
  • Hardware Design
    • Schematics
    • PCB
  • Software Design
    • Wireless
    • User Interface
    • Protocol
  • Hardware Prototype

License

The strobit hardware design is covered by The TAPR Open Hardware License. Please see http://www.tapr.org/ohl.html for further details.

Schematics:

Strobit Triggr Block Diagram Strobit Triggr Topology StrobIt Triggr Schematic

Prototype Details

Firmware Description

Protocol Description

Downloads – Files associated with the project

Tests – Tests done so Far

In the Wild – Version of this trigger made by others

I’m toying with the idea of putting together a low cost kit for the enthusiast. i.e. PCB, pre-programmed PIC, etc. So we could all benefit with a bulk order of the components. If your interested please email me using the contact form the top menu or use the mailing list signup on the right to give me an indication of numbers interested. Once I finaliaze the design and get some idea of numbers I’ll get a better idea of price. At the moment it will only be available in kit form due to FCC and other Licensing regulations.

Future Improvements:

  • Higher Sync Speed.
  • Frequency Hopping.
  • Forward Error Correction.
  • Power management.
  • UI to change settings, Channel etc.
  • Save settings in Flash memory.

BuzzBot

Introduction 

The Buzzbot idea came to me when i was trying to think what can i do to learn the picaxe uController, something practical, well rather than just flashing Leds and buzz buzzers anyway. What I wanted to do was something robotic that is cheap and easy as I don’t have much of a workshop facility available to me just yet to assemble any bases. 

Recycle 

We had just moved house and whilst doing the spring clean of some toy boxes and throwing alot of my childrens toys into thte “garage sale” box I came across the Buzz Lightyear Remote control buggy.  Basically a 6 wheel buggy with a psycho looking buzz with missile launchers as hands that raises and releases the missiles.  Well the missiles were long lost and what interested me was in using it as the base for my “buzzbot” is that most of the work is already done for me. i.e. I don’t have to build a base and look for motors etc.  I just want to get down to the nitty gritty of interfacing the PICAXE into something and playing around with it. Another thing that I think will work in my favour is that the Left and right wheel drives seem to be independant of each other as this thing from memory could turn on a dime, so therefore there must at least two motors, and the necessary driver circuits in place for me to use.

 BuzzBot Buzz Buggy Side

The Autopsy

Upon dissasembly it looks as though I was right, a gearbox and motor for the left and right drives (front two wheels on each side are geared , while the rear is free wheeling) also a circuit board with a simple RF Receiver and a heap of transistors, which after some initial tracing leads me to suspect are the H-Bridge Drive implementation for the motors, Left, right and the psycho buzz torso aka Missle launcher (he raises up to fire) woohoo, most of the work is already done.

Buzz Buggy InsideBuzzBot Drive Trainbuzzbot control boardbuzzbot -  inside buzz

Man he must be on crack!

buzzbuggy - psycho buzz

Next Steps…..

Ok since I have now dissected the Buzzbuggy it will now be re-assembled back into the “buzzbot”  minus the psycho buzz torso, as I just want to use the base as my test platform for the PicAxe.  I now need to trace through the circuit and see where I can tap into for the motor control, and also add some sensors. 

 Stay Tuned….