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  The simple two wheel robot above is constructed by taping two servos to the back and attaching hobby airplane wheels to the servo shaft. The servo has been modified by removing the internal stopper notch and potentiometer. The potentiometer is replaced with a fix voltage divider resistor or a trim pot. This allows the servo to be used as a continuous spinning motor. The speed and direction, instead of position, can then be controlled with the SV203B or SV203C. The two bump sensors are just switch contacts connected to two of the A/D ports. 

The code below can be compiled and downloaded to the SV203B/C and run autonomously. 
Dim BumpL as Bit 0 of RC        'Sensor 1 
Dim BumpR as Bit 1 of RC        'Sensor 2 

Const Stop = 0 
Const Fwd1 = 10 
Const Fwd2 = 245 
Const Rev1 = 245 
Const Rev2 = 10 

Main: 
  Servo1 = Fwd1 'Forward 
  Servo2 = Fwd2 
  If BumpL = 1 then 
    Call HitLeft 
  End if 
  if BumpR = 1 then 
    Call HitRight 
  end if 
goto Main 

Sub HitLeft 
    Servo1 = Rev1       'Reverse 
    Servo2 = Rev2 
    Delay 1000  '1 Sec delay 
    Servo1 = Fwd1       'Spin Right 
    Delay 500   '0.5 Sec delay' 
End Sub 

Sub HitRight 
    Servo1 = Rev1       'Reverse 
    Servo2 = Rev2 
    Delay 1000  '1 Sec delay 
    Servo1 = Fwd2       'Spin Left 
    Delay 500   '0.5 Sec delay' 
End Sub