# IF Statement Help?

2 views (last 30 days)
Ravyn Schmidt on 18 Nov 2021
Commented: Ravyn Schmidt on 23 Nov 2021
I have a setup with a Potentiometer setup to a servo.
I've now set up 4 LEDs and they are supposed to come on depending on the angle of the servo. I think I have everything right, EXCEPT the IF statemnt. I would really appricate some help. It's supposed to light up one LED from 0-45 degrees, 2 at 45-90, etc.
while(1) %infinite loop, use CTRL+C to end code execution
potPosition = readVoltage(a,potPin); %measure position of potentiometer
%use linear interpolation to scale the potentiomenter reading to be between 0 and 1.
servoPosition = interp1([0 5],[0 1],potPosition);
writePosition(s,servoPosition); %set position
CurrentPosition = readPosition(s)*180; %convert position to degrees
fprintf('Current servo position is %4.1f degrees\n', CurrentPosition);
pause(1) %pause for one second before checking the potentiometer again
%if angle of servo is X turn on 1 -4 LEDs
if CurrentPosition < 45
writeDigitalPin(a,gPin,1);
writeDigitalPin(a,rPin,0);
writeDigitalPin(a,bPin,0);
writeDigitalPin(a,yPin,0);
if CurrentPosition < 90
writeDigitalPin(a,gPin,1);
writeDigitalPin(a,rPin,1);
writeDigitalPin(a,bPin,0);
writeDigitalPin(a,yPin,0);
if CurrentPosition < 135
writeDigitalPin(a,gPin,1);
writeDigitalPin(a,rPin,1);
writeDigitalPin(a,bPin,1);
writeDigitalPin(a,yPin,0);
if CurrentPosition < 180
writeDigitalPin(a,gPin,1);
writeDigitalPin(a,rPin,1);
writeDigitalPin(a,bPin,1);
writeDigitalPin(a,yPin,1);
else
writeDigitalPin(a,gPin,0);
writeDigitalPin(a,rPin,0);
writeDigitalPin(a,bPin,0);
writeDigitalPin(a,yPin,0);

Chris on 18 Nov 2021
Edited: Chris on 18 Nov 2021
This statement would flow like this, for a 30-degree angle (in pseudocode):
if CurrentPosition < 45
% True, so...
write([1 0 0 0])
if CurrentPosition < 90
% Also true, so...
write([1 1 0 0])
if CurrentPosition < 180
% Still true...
write([1 1 1 0])
if etc
end
end
end
If CurrentPosiiton > 45, none of this ever triggers.
Try elseif
if CurrentPosition < 45
% [0-45) degrees?
write([1 0 0 0])
elseif CurrentPosition < 90
% if previous wasn't true, [45-90) degrees?
write([1 1 0 0])
elseif etc...
else
write([0 0 0 0])
end
Ravyn Schmidt on 23 Nov 2021
Thank you so much ! :)