Hiskey.us

This remote control car cost about $10 at fred meyer, which was interestingly cheaper than buying equivalent wheels / motors / base seperatley.

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To power this device and the microcontroller I attached 4 AA batteries in series. Technically this provides about double the voltage the original RC circuit needed, but it didn't seem to hurt the motors any running them at this voltage level. 4 AA's were needed in order to provide the appropriate voltage for the Basic Atom Pro 24. I just duct taped the battery holder to the back of the robot, which worked well.

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In this picture you can see the front of the robot with the light sensitive resistors and my custom made touch sensor. The touch sensor basically works by having the basic atom pro reading the voltage on that line, if the front part is pressed it closes the circuit and so pulls the voltage high. There is a resistor there as well on the actual circuit part to prevent short circuiting. Again we see obligatory judicious usage of gorrilla duct tape, which is essential for any project.

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In this picture you can see the circuit itself mounted on the RC car with gorilla duct tape. For significantly greater detail click the image. Basically though, as I said above, it just has 4 light sensitive resistors (see week 3) pointed forward, left/forward, right/forward, and up. The RF transmitter there is connected up to send robot state back to a reciever (see week 7 for more details). The chip you see there is an H-Bridge (see week 5 for more details) which controls the motors. The H-bridge handles inductive flow from the motors as well as allows for very easy switching of directions of the motors. One side is connected to the rear motors for going forward/backward. The other side of the H-bridge is connected to the front wheels motor which handles turning left or right. The front wheels are spring loaded to return to the centered position if the motor is off. I added a bunch of capacitors there on the power lines to even out the power flow as in the past I've found when dealing with battery powered motors connected on the same line as the basic atom pro 24 microcontroller that tends to be needed to avoid some weird microcontroller behavior such as resetting and what not. In this case it might not have been needed as usually I use a 9 volt battery to power and that only gives .3 amps, but in this case with the AA's that provide about 2.5 amps and plenty of voltage, it probably wouldn't have been a problem. But just in case I added the cap's anyways.

LightLeft VAR WORD
LightRight VAR WORD
LightFront VAR WORD
LightTop VAR WORD
TouchFront VAR BIT
TouchFront2 VAR WORD

MotorStateForward CON 0
MotorStateBackward CON 1
MotorStateLeft CON 2
MotorStateRight CON 3
MotorStateStraight CON 4

MotorStateCurrent VAR BYTE

TransmitterPin CON P14

TouchFrontPin CON P11

LightLeftPin CON P0
LightRightPin CON P3
LightFrontPin CON P1
LightTopPin CON P2

MotorRearPin1 CON P7
MotorRearPin2 CON P6
MotorRearEnablePin CON P5

MotorFrontPin1 CON P8
MotorFrontPin2 CON P9
MotorFrontEnablePin CON P10

TurnToggle VAR BYTE

Initialize:
    Input LightLeftPin
    Input LightRightPin
    Input LightFrontPin
    Input LightTopPin

    MotorStateCurrent = MotorStateForward
    TurnToggle = 0
;end initialize

Main:

    GoSub FollowLight

goto main

FollowLight

    GoSub SetTouchValue

    if(TouchFront = 1) then
        GoSub TurnRandom
    endif

    if((LightRight > LightLeft) AND (LightRight > LightFront) AND (LightRight > LightTop)) then
        GoSub GoForward
        GoSub TurnRight
    elseif((LightFront > LightLeft) AND (LightFront > LightRight) AND (LightFront > LightTop))
        GoSub GoForward
        GoSub GoForward
    elseif((LightLeft > LightFront) AND (LightLeft > LightRight) AND (LightLeft > LightTop))
        GoSub GoForward
        GoSub TurnLeft
    elseif((LightTop > LightFront) AND (LightTop > LightRight) AND (LightTop > LightLeft))
        GoSub StopMotors
    endif

    GoSub SendState

return

SendState

    PULSOUT 0, 1200 'used for synchronization
    SEROUT 0, I9600, ["!", LightRight.HIGHBYTE, LightRight.LOWBYTE, LightFront.HIGHBYTE, LightFront.LOWBYTE, LightLeft.HIGHBYTE, LightLeft.LOWBYTE, LightTop.HIGHBYTE, LightTop.LOWBYTE, TouchFront2.HIGHBYTE, TouchFront2.LOWBYTE, MotorStateCurrent.HIGHBYTE, MotorStateCurrent.LOWBYTE]

return

SetTouchValue

    TouchFront = In11
    if(TouchFront = 1) then
        TouchFront2 = 1
    else
        TouchFront2 = 0
    endif

return

SetLightValues
    ADIN LightLeftPin, LightLeft
    ADIN LightRightPin, LightRight
    ADIN LightFrontPin, LightFront
    ADIN LightTopPin, LightTop
return

TurnRandom
    GoSub Gobackward

    if(TurnToggle = 0) then
        GoSub TurnRight
        TurnToggle = 1
    else
        GoSub TurnLeft
        TurnToggle = 0
    endif

    Pause 1000
return

GoForward
    High 8
    Low 7

    MotorStateCurrent = MotorStateForward
return

GoBackward
    High 7
    Low 8

    MotorStateCurrent = MotorStateBackward
return

TurnRight
    High 2
    Low 1

    MotorStateCurrent = MotorStateRight
return

TurnLeft
    High 1
    Low 2

    MotorStateCurrent = MotorStateLeft
return

GoStraight
    Low 1
    Low 2

    MotorStateCurrent = MotorStateStraight
return

StopMotors
    Low 1
    Low 2

    Low 7
    Low 8
return

EnableMotors
    High 0
    High 9
return

DisableMotors
    Low 0
    Low 9

    Low 8
    Low 7

    Low 1
    Low 2

return

LightRight VAR WORD
LightFront VAR WORD
LightLeft VAR WORD
LightTop VAR WORD
TouchFront VAR WORD
MotorState VAR WORD

main:

    SERIN 0, I9600, [Wait("!"), LightRight.HIGHBYTE, LightRight.LOWBYTE, LightFront.HIGHBYTE, LightFront.LOWBYTE, LightLeft.HIGHBYTE, LightLeft.LOWBYTE, LightTop.HIGHBYTE, LightTop.LOWBYTE, TouchFront.HIGHBYTE, TouchFront.LOWBYTE, MotorState.HIGHBYTE, MotorState.LOWBYTE]
    SEROUT s_out, I4800, ["LightRight: ", DEC LightRight, 10, 13, "LightLeft: ", DEC LightLeft, 10, 13, "LightFront: ", DEC LightFront, 10, 13, "LightTop: ", DEC LightTop, 10, 13, "TouchFront: ", DEC TouchFront, 10, 13, "MotorState: ", DEC MotorState, 10, 13]

goto main