Notes re ignition timing schematic (ign_schm.jpg)

    The main IC is an ATMEL 8535 microcontroller.  The display IC (on the
    right) is an AMPIRE 162B (2 lines of 16 chars).  The crystal is 8MHz.

    Connectors on left :

    a) 6 pins - to car electrics
        a) analogue input 2 (unused)
        b) analogue input 1 - from MAP sensor
        c) analogue +5V
        d) earth
        e) ignition switch (0 = off, +ve = on)
        f) throttle switch (0 = closed, +ve = open)

    b) 5 pins - SPI programming link

    c) 3 pins - points and coil
        a) points input (0 = closed, +ve = open)
        b) earth
        c) coil control (0 = on, +ve = off)

    d) 2 pins - power in
        a) +5V
        b) earth

    Connectors on right :

    a) 3 pins - to display panel potentiometer
        a) +ve to right terminal
        b) earth to left terminal
        c) from centre terminal

    b) 6 pins - to SPDT switch and push button switches
        a) earth for push button switches
        b) to YES button switch
        c) to NO  button switch
        d) to top of SPDT centre-off switch
        e) to bottom of SPDT centre-off switch
        f) to centre of SPDT centre-off switch

    The LED connected to PB7 flashes each 500ms
    The LED connected to PD6 flashes when coil on

    The trim pot near the display sets the voltage for display contrast


    This circuit runs on 5 volts and must interface with a car running on
    about 14 volts.  Inputs have outwards diodes so they can be pulled low
    or allowed to float high.  The coil control output supplies 5ma to keep
    the coil off or supplies 0ma to energise the coil.


    The control panel on the front of the box contains :
    a) the display that shows timing and feedback when changing entries
    b) a potentiometer that functions as a 16 position switch
    c) a three position switch (normal, admin, or live entry mode)
    d) 2 push button switches (YES and NO buttons)