Two motors and two 12v Gel Cells on a piece of wood I might use as the base board (December 2002)

First thing was to choose a suitable computer to get a motherboard from. I have several computers I could have used but the one I chose was more suitable because:

• It was a 386- Not worth much if I break it, not too low powered and easy to program

• It had onboard mouse(PS2), keyboard(PS2), VGA, parallel and 2 COM ports. This means it is essentially a single board computer except it had a daughter card with expansion slots and a card to replace the optional extended memory cache. Once I figure out which pins connect to which others, I should be able to puts loops of wire in and get rid of the need for any extra boards at all.

• It had an onboard speaker and power LED. There were no other switches. It had a main power switch on the PSU and that was it.

I got the computer from a company that was throwing them out. It refused to recognize the hard drive no matter what I tried so I disconnected the hard drive and all its cabling. The case was a massive metal thing, but the motherboard was tiny for that age machine so I took the motherboard out and put it in a cardboard box. The next thing was to figure out how to power the motherboard without using its PSU. I used a digital multimeter to measure the output voltages on the motherboard and floppy dive power connectors. The results I got were as follows:

Motherboard connector
 ____________________________________________________________
|White|Orange|Blue|Black|Black|Black|Black|Yellow|Red|Red|Red|
|  +5 |  +12 | -12|  0  |  0  |  0  |  0  |  -5  | +5| +5| +5|
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Large power connectors
 ______________________________
| Yellow | Black | Black | Red |
|  +12v  |   0v  |  0v   | +5v |
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Small power connectors
 ______________________________
| Yellow | Black | Black | Red |
|  +12v  |   0v  |  0v   | +5v |
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I was intending to make the robot primarily out of wood because I am better at making things out or it than I am at making things out of metal. I was thinking of a plywood base with blocks underneath to hold axles etc. So far I have some wheels and axles and 1 motor(12v wheelchair type). The motor has a reduction box fitted to it that brings it down to about the right speed (Have used it in a go-cart).

Housing for motherboard completed(September 2003)

I'm trying to power the motherboard from batteries. I'm going to need something to drop the voltage from 12v to 5v for the motherboard logic. I'm a bit lacking in knowledge on that area so I might just do some of the programming side instead.

	A view of the drive chain to the rear wheels (7th Feb 2004)
	Plan view of the back of the robot showing offset motor (7th Feb 2004)
	Cables connected to ports on motherboard (7th Feb 2004)
	A plan view of my robot(7th Febuary 2004)

I've collected some 78xx series voltage regulators, they are from many different common electrical appliances and power supplies. I collect old broken electronic equipment so it was just a job of desoldering the components and making them work in my circuit. The above pics show the circuit that provides regulated +12v and +5v relative to GND. The outputs all come out to the strip of terminal block in the foreground.

	This is the circuit I built done freeform with bits of terminal block. Unfortunatly when powered up like this the regulators shut down after about a minute from thermal overload and I have to wait for it to cool down before trying again.
	Plan view showing the regulators bolted to a piece of aluminium
	Another view showing the motherboard working from the 7Ah gel cell
	A picture showing the steering arm and stub axle assembly. Here you can see the poor quality of my welding but hey, nobody's perfect.
	A plan view of the chassis showing the position the front steering will go.

M_CNTRL2.BAS
'This program controls two motors attached to H-Bridge control
'circuits that are attached to lpt1.
'1-4 is motor1, 5-8 is motor2
'1,2,5,6 are high side drivers
'3,4,7,8 are low side drivers
'
'Programmed by Ralph Hughes 2004
'
DECLARE SUB center (t$)
DIM pin(1 TO 8)
FOR i = 1 TO 8: pin(i) = 0: NEXT i
m1stat = 0: m2stat = 0
CLS
LOCATE 6: center ("Ralph's Interface/Motor Controller")
LOCATE 7: center ("(Use numpad for controlling)")
LOCATE 9, 17: PRINT "Motor A"
LOCATE 10, 17: PRINT "7:Forward"
LOCATE 11, 17: PRINT "4:Stopped <"
LOCATE 12, 17: PRINT "1:Reverse"
LOCATE 9, 57: PRINT "Motor B"
LOCATE 10, 57: PRINT "8:Forward"
LOCATE 11, 57: PRINT "5:Stopped <"
LOCATE 12, 57: PRINT "2:Reverse"
DO
  DO
    a$ = INKEY$
  LOOP UNTIL a$ <> ""
  SELECT CASE a$
    CASE CHR$(27)
      OUT 888, 0
      END
    CASE "1": GOSUB m1rev
    CASE "4": GOSUB m1stop
    CASE "7": GOSUB m1fwd
    CASE "2": GOSUB m2rev
    CASE "5": GOSUB m2stop
    CASE "8": GOSUB m2fwd
    CASE ELSE: LOCATE 1, 1: PRINT "Key doesn't do anything": SLEEP 1: LOCATE 1, 1: PRINT SPACE$(60)
  END SELECT
  GOSUB out2motors
  GOSUB drawstat
LOOP UNTIL a$ = CHR$(27)
END
drawstat:
LOCATE 10, 17: PRINT "7:Forward  "
LOCATE 11, 17: PRINT "4:Stopped  "
LOCATE 12, 17: PRINT "1:Reverse  "
LOCATE 10, 57: PRINT "8:Forward  "
LOCATE 11, 57: PRINT "5:Stopped  "
LOCATE 12, 57: PRINT "2:Reverse  "
LOCATE 11 - m1stat, 27: PRINT "<"
LOCATE 11 - m2stat, 67: PRINT "<"
RETURN
out2motors:
t = 0
IF pin(1) = 1 THEN t = t + 128
IF pin(2) = 1 THEN t = t + 64
IF pin(3) = 1 THEN t = t + 32
IF pin(4) = 1 THEN t = t + 16
IF pin(5) = 1 THEN t = t + 8
IF pin(6) = 1 THEN t = t + 4
IF pin(7) = 1 THEN t = t + 2
IF pin(8) = 1 THEN t = t + 1
OUT 888, t
RETURN
m1fwd:
pin(1) = 1:pin(2) = 0:pin(3) = 0:pin(4) = 1
m1stat = 1
RETURN
m1stop:
pin(1) = 0:pin(2) = 0:pin(3) = 0:pin(4) = 0
m1stat = 0
RETURN
m1rev:
pin(1) = 0:pin(2) = 1:pin(3) = 1:pin(4) = 0
m1stat = -1
RETURN
m2fwd:
pin(5) = 1:pin(6) = 0:pin(7) = 0:pin(8) = 1
m2stat = 1
RETURN
m2stop:
pin(5) = 0:pin(6) = 0:pin(7) = 0:pin(8) = 0
m2stat = 0
RETURN
m2rev:
pin(5) = 0:pin(6) = 1:pin(7) = 1:pin(8) = 0
m2stat = -1
RETURN
SUB center (t$)
LOCATE , 40 - (LEN(t$) / 2): PRINT t$
END SUB