home  >  Zeaker2 < Zero2 > Double Vision 27 February 2024

Zero2 - by David Buckley July 1984
Zero2 - HM
Designed by David Buckley
Expandable Turtle controlled over an umbilical from an host computer, driven by stepper motors and capable of precise movements, is able to follow lines using the inbuilt line following sensors.
Sold by Intergalactic Robots Ltd.
Design started July 1984.
Size - 7" * 6" * 4".

IGR advert April 1985
IGR advert April 1985
    Maplin Magazine article
Maplin Magazine article
    Sinclair QL Zero2 control program
QL control program

QL-program Commands

I wanted to run Zero2 from my Zero2 control program that I wrote for the QL back in 1986 however floppy disks and microdrive cassettes for original QL computers have not survived too well the passing of time and so I tried various QL emulators for a PC. Only QPC-2 had an emulated serial port which connected to the original PC serial ports and also to USB/serial ports. However the PC operating system got in the way and operation of Zero2, which depended on a precisely timed byte stream through the serial port, was anything but smooth. UPDATE - at Feb 2024 using QPC-II v5.02 Zero2 operation is very smooth.

I was ill for the first four months of 2017 and couldn't walk much. Once I was a little better I decided to get Zeaker2 and Zero2 running from the PC by changing my QL program to send out ASCII commands instead of the byte stream and using an Arduino Uno to decode the ASCII commands and send out the required byte stream. I modified a program I had written for Bambino and built simple Arduino shields to take the umbilicals. Also I added a Pen-cam stop to allow automatic initialisation of the pen position to up.

Zero2 and Zeaker2

The Arduino programs, controlled fom a serial terminal, allow sixteen 32 byte command strings to be stored and replayed as well as allowing control by converting the ASCII commands from the PC.

  • Arduino Shield

    2023-09-07 Arduino Shield upgraded with an IR sensor and code upgraded to receive Sony commands from a handset
  • Arduino code
    receives ASCII serial commands @9600 from a terminal or program and controls Zero2

    Everything else about Zero2

    Late in 2005 I received a request for information on Zero2.
    These pages are the result of going through several box files of papers and running Zero2 under the Zero2 QL program in the QPCII emulator under Windows-XP.
    David Buckley
    30th August 2006


    Zero2 Microrobot

    @24 June 2017 -web # Quick Guide to using Zero2
    User Manual
    Robotics on the QL - David Buckley Robotics on the QL 1 Quanta magazine
    Robotics on the QL 2 Quanta magazine
    Robotics on the QL 3 Quanta magazine Feb/Mar 2007
    Article for Maplin Magazine 1985 - circuit explanation - David Buckley - [revised 22 January 2007]
    Maplin Magazine, March May 1985 - David Buckley - [revised 22 January 2007]
    Maplin Magazine, June August 1985 - interfacing - Dave Goodman
    Assembly Instructions - Colin Freestone
    # Power requirements
    # Programing
    # Programing Model - see Maplin Article for larger diagrams
    # Spectrum BBC interface
    # Spectrum/QL/PC-serial interface circuit
    # PC-serial interface photos
    # Motor Wiring
    # Motor and Speaker Cables
    # Add-Ons
    Zero2 software Sinclair QL SuperBASIC control program - David Buckley
    #Sinclair Spectrum #ZeroDrive Z80 code for Spectrum LOGO/BASIC - Richard Moyle #BBC-B
    #Research Machines 480Z
    Data Sheets folder view
    ID31-farnell23919.pdf - stepper motor
    ID31-1.jpg - stepper motor
    Proposed embeded Software-Utilities
    # Proposed Game
    # Proposed Trailer Lift
    # Spectrum RS232 4800 baud accuracy
    #Spectrum Interface-1 RS232 routines
    Development of Zeaker2 and Zero2
    UK Design Registration #Register Entry
    #Zero2 drawings
    History 1983 August - IGR - Inter Galactic Robots Ltd - incorporated.
    1984 June - Zero2 designed.
    1985 14th February - Press Launch of Zero2 at the Institution of Mechanical Engineers, 1 Birdcage Walk, London.
    1985 April - production of Zero2 started.
    1986 - Starting in First Quarter industrial action by teachers severely affected sales,
    1986 6 November - IGR ceased trading.
    1987 16 February - Statutory Meeting of Creditors.

    2017 Zero2 Robot - World of Spectrum.

    Quick Guide to using Zero2

    Power requirements
    12 volt 1 amp supply for the motors
    5 volt at ~150mA for the electronics

    The original power supply, 9V 12.6VA, gave 14v off load and 9v on load, and the original interface had a 5v regulator to supply the electronics, see the interface diagrams.

    Using an original Zero2 PSU
    Zero2 total current 870mA @ 9.75v
    Zero2 electronics only, 130mA @ 12.9v

    Setup Zero2 as in the photograph and connect to a computer Serial port through a suitable interface, see the interface diagrams.
    Zero2 responds to character codes sent at 4800 baud, no parity, and 2 stop bits.
    Each time a motor code is sent the motors will step to their next position, if codes are sent out of sequence then the motors will just judder.
    When driving the motors a small delay must be inserted after each character to give time for the motor to turn. When Zero2 was conceived time delays generally were not necessary because the computers were not too fast. If a delay can't be inserted then sending the same character several times will have the same effect. In fact the QL software supplied with Zero2 did just that.

    Sending the codes  5, 0,10,15  makes Zero2 go forwards four 0.5mm steps
    Sending the codes  5, 0,10,15  again makes Zero2 go forwards another four steps
    Sending the codes  5, 0,       will make Zero2 go forwards another two steps
    Sending the codes       10,15  will make Zero2 go forwards another two steps

    Sending the codes 10, 0, 5,15 makes Zero2 go backwards four 0.5mm steps Sending the codes 10, 0, 5,15 again makes Zero2 go backwards another four steps Sending the codes 10, 0 will make Zero2 go backwards another two steps Sending the codes 5,15 will make Zero2 go backwards another two steps

    similarly Sending the codes 6, 0, 9,15 makes Zero2 turn right four 1 degree steps Sending the codes 9, 0, 6,15 makes Zero2 turn left four 1 degree steps and Sending the codes 7, 3,11,15 makes Zero2 turn right two degrees only the left wheel moves four 0.5 degree steps Sending the codes 13,12,14,15 makes Zero2 turn left two degrees only the right wheel moves four 0.5 degree steps

    You will note that all the sequences have been arranged to end on 15 so no matter what the next sequence is that is sent it will continue on without missing any steps.
    By sending individual codes in the correct sequence Zero2 can be made to move in 0.5mm steps
    and turn through 0.5 degree (only one wheel is moved).

    for detailed information see the Manual Chapter 4 - Writing to Zero2

    Programming Model

    Spectrum/BBC interface

    Spectrum interface
    The D9male on the Spectrum interface can be plugged into a standard PC D9 serial connector using a female/female gender changer.
    However direct control of Zero2 from a Windows PC program will be poor because of Window's Serial Buffers.
    D9 serial interface 12v power 3.5mm jack-socket, tip +ve

    Spectrum/QL/PC-serial interface circuit

    PC-serial interface 2006

    The umbilical for Zero2 uses Sinclair QL CTL/Joystick connectors, similar to BT phone connectors but left-handed and with 'W' style polarisation.
    Ordinary ribbon cable can be used with them by stripping the ends and lightly touching the ends with solder to make them easier to insert in the plugs, there are holes just to the end of the contacts so you can see the cores going to each contact, make sure a core goes to each contact before pressing down the contacts.

    6-way W-polarisation socket
    3.5mm jack socket for standard Zero2 12v 1A 12.6VA PSU (14v off load)
    5v 1A 7805 regulator
    1A In4001 diode
    2x 0u1 disc ceramic
    100u 6v
    green LED
    220R resistor
    9pin D R/A socket
    The Four way header [1:0v][2:--][3:Tx][4:Rx] in the bottom right is to connect the interface to to a Parallax Stamp board, [1:0v][2:--][3:Rx][4:Tx]
    and the three way header is my standard serial header [1:Rx][2:0v][3:Tx].

    Motor Wiring

    Motors are ID31004 2.8N.cm 175mA per coil @12v, 7.5deg/step max 240step/sec, so 350mA per motor.
    drive boss is 0.301"dia giving 24.02 circumference so each step is 0.5mm

    Motor and Speaker Cables - PCB v3

    Note - all motor cable connectors are wired the same.
    Using the above colour code, when plugged onto the PCB
    - on the RHS the green wire should be at the top
    - on the LHS the green wire should be at the bottom


    A lifter and pallets to allow Zero2 to do a horezontal Towers of Hanoi. The pallets were stacked in a line rather than the normal way of stacking rings vertically. The vertical column is fixed in place of the pen.
    This is similar to the proposed Trailor-Lift.

    2023-05-19 added note re Spectrum interface connecting to a PC
    2023-05-19 added photos of Spectrum interface
    2023-05-19 corrected - "The umbilical for Zero2 uses Sinclair QL serial connectors" to "..CTL/Joystick connectors"