PICAXE Code - Line Following

This is the PICAXE code used for the buggy on the protoype testing day is shown below. It impliments the use of if....else command. Low's and High's are used to send outputs to the connected components such as the LED's and motors. It also uses sub-routines to keep the code neat and efficient as possible.



symbol switchstate = b0

main:

if switchstate = 0 then
debug switchstate ;used so we can see the state the swith b0 is in
goto program1


else
goto program2
endif

goto main


program1: ;used to follow the track

readadc 1, b1 ;reads and converts the analogue input from left LDR
debug b1 ;used to calibrate the left LDR
readadc 2, b2 ;reads and converts the analogue input from right LDR
debug b2 ;used to calibrate the right LDR


high 5 ;sends an output high to the two LED's
high 6

if b2 > 110 and b1 ;if the left LDR is on white and the right LDR on black
goto right
endif

if b2 <> 110 then ;if the left LDR is on black and the right LDR on white
goto left

else ;otherwise move forwards
goto straight

endif
goto main

program2: ;used to identify the symbols

readadc 1, b1 ;reads and converts the analogue input from left LDR
debug b1 ;used to calibrate the left LDR
readadc 2, b2 ;reads and converts the analogue input from right LDR
debug b2 ;used to calibrate the right LDR


high 5 ;sends an output high to the two LED's
high 6

if b2 > 110 and b1 > 110 then ;if the left LDR is on black and the right LDR on black
low 1 low 2 low 3 low 4 ;stay stationary for three seconds
pause 3000
endif

goto program2

if b2 > 110 and b1 ;if the left LDR is on white and the right LDR on black
goto left ;turn left for three seconds
endif

if b2 <> 110 then ;if the left LDR is on black and the right LDR on white
goto right ;turn right for three seconds

else ;otherwise move backwards
goto back
endif

goto main


straight:

low 1 high 2
low 3 high 4

goto main

right:


low 1 low 2 low 3 high 4
goto main

left:

low 1 high 2 low 3 low 4
goto main


back:

low 2 high 1 low 4 high 3
goto main