Strobit M8 Files

Jans Gentsch has made his compact version of the Strobit Triggr available to the community, his version, the Strobit M08 based on AVR design can be found here.   Please note that there are a couple of things that need doing to the PCB, if you get a chance to implement Jans design, please post back any changes to me so I can make them available.

Hello Stephen,

I’ve attached the Eagle-Design-Data as well as the source code. I haven’t found time to do anything on those since my post, so the are not in the best state. There are a few Problems with the board design:

Transmitter – There is a connection missing between the processor and NIRQ of the transmitter-module (the transmitter module doesn’t have a fifo, so that the nirq-line is needed to clock out the data). I just added a piece of loose wire during assembly.
Receiver – NIRQ isn’t connected as well, so I am constantly polling, not really a power saving design. however I am still running on the first set of batteries so it’s not like they are being drained empty immediatly.
IO-Board – Thr optocoupley was meant to sit on the bottom side but I got confused. It has to sit on top now.

Getting everything into the housing was a major challenge.

The source code has been developed using avr-gcc and the eclipse ide.
As it stands only the most basic function, tiggering, is working. The control flow will have to be reworked in order to add the rest of the functionality. And of course my “magic” trigger id should be changed.

Have fun!

Alle the best
Jan

Files

You will need Eagle PCB to view/edit the schematics and PCB files, found here –http://www.cadsoft.de/

The firmware is written using winavr found here – http://winavr.sourceforge.net/

Protocol

Protocol:

Full Detail can be found here on the wiki – http://wiki.everythingrobotics.com/index.php?title=Draft_Proposal

The trigger packet transmitted is 7 bytes long.  Preamble(3 bytes), Sync(2 bytes), trigger command (1 byte) and CRC byte.

The Preamble is used by the the RF module to tune the Receiver.

The Sync word is used by the RF modules receiver circuit to know when a valid transmission is occuring and not just interference.  This SYNC word can be used as a future PAN address, i.e. all your units are set to the same unique SYNC pattern then your units operating in the same area as other trigger units on the same frequency will not be triggered by your units and visa-versa.

If an invalid packet is detected by the CRC then the packet is dropped and the strobe will not fire.  This is where some future work can be done with forward Error Correction, so a corrupt packet could be rebuilt and still used by the slave, i.e. the strobe could still fire even if some corruption is detected.

Currently the slaves so not communicate back to the master in anyway.

Back – Firmware Triggr Home

Prototype

Prototype boards RF module Testing

Prototype Specs:

  • PIC16F88 running on internal 8MHz Clock – low cost and very popular, free development tools available, i.e. C compiler.
  • Works in unlicensed 915MHz ISM Band(Australia/US), can work at 433Mhz by changing RF module(US/EU/Australia).
  • RF uses FSK Modulation – Less prone to interference sources.
  • All aspects of the RF module is configurable via the firmware, i.e. frequency, Tx power, receiver bandwidth, modulation, datarate etc.
  • Indoor Range – ~30m+ works all through my house non line of sight, i.e. through multiple single brick walls, with transmitter at furtherest end, close to AV, TV & WIFI (i.e. interference sources) and receiver roaming throughout the house in different rooms, microwave oven also in the mix. No packets lost or dropped so far, but more testing needing to be done.
  • Outdoor Range – Untested, but from indoor tests I would guess 150-250m easily.
    Update:
    Outdoor Test Results here
  • Antenna – Simple 8cm whip (i.e. a single piece of wire), these RF units are matched to 50Ohm so an SMA antenna could be used
  • Sync to 1/125 – in theory it could easily sync upto 1/1000 as the Rf modules are capable of the bitrate necessary, however range will be affected by the higher the speed, also the processor / oscillator arrangement may need to be revised to handle the higher interrupt rate to process data, i.e may need to use a chip with onboard SPI support etc.
  • Can act as Master or Slave.
  • Can be programmed to use any frequency from 902Mhz to 928Mhz (using the 915Mhz module), using the 433Mhz Module will allow similar channels.
  • Can be triggered by a contact closure on Trigger Input. i.e. from camera
  • Can be manually triggered by test button.
  • Trigger output is isolated upto 400V, i.e. can safely trigger old stobe units with high voltage on hotshoe / sync terminals
  • Powered by x3 AA batteries. Currently no power management in the firmware.
  • Cost per prototype board AUD$ ~25

Note on the costs:

  • Most components are sourced via local retail outlets so are probably definately more expensive that sourcing elsewhere, i.e. this can be built a lot cheaper i.e. Sub $10 in parts.
  • Some of the components I had lying around at home so I’ve just used market prices in my estimates.
  • No freight was added to construction costs.
  • Some components have minimium order quanties such as the RF module.

Back – Triggr Home Next – Firmware

EBAY Trigger Receiver PCB

A couple of design changes,  main one being I could not physically fit a single design into the existing housings that would encompass the Tx and RX, the RX housing is the problem as it’s a fairly small board so that means I’ve had to change the processor so that I can physically fit everything as well as the RF onto the board, so now a single design using the PIC 16F873A now becomes 2 circuits, Tx and Rx using a PIC16F88 as the MPU.

Receiver PCB

Continue reading “EBAY Trigger Receiver PCB”

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….