+Axltrain You can also look for a Pro Micro. Same size, different USB socket.

That would definitely be cool! However, the practical limit of these sensors is about 30cm (a foot), and this train with fresh batteries at the set speed (4 of 7, so middle speed) requires 16cm to stop just in time, so there's not much room to play around with in terms of adaptive speed. But don't worry! I will be featuring adaptive speed control in a later video, featuring a 3-axis accelerometer.

You could use a PID (Proportional-Integral-Derivative Control) to set a specific distance at which the train should stop from the wall. Arduino has already a specific library for this function, i use it in many application as for example a control temperature.

I have a Lego mindstorms ev3 program for that. It uses the IR sensor and a motor, and sets the motor speed to the proximity distance. If the train is far from a wall it goes fast, but as it gets closer, it slows down. You could also use this concept in a Lego car.

If you check Tutorial 1, you'll see how to control lego motors using an L298 motor controller. You can convert that solution to control PF motors, but you'll need to sacrifice a PF extension cable (ie cut one end off) to attach it to the motor controller. However, If you put 9V in (the power from the battery box) you'll get less than 9V out, so the train will never run at full speed. You can use the PF battery box using a similar cable to drive the arduino.

It would, but then you need a 9v motor controller (L298N or similar) and that requires more than 9V, so more power than the battery box can provide. The best solution would be to replace the PF battery box and IR controller with bigger batteries (3x18650 or similar Li-ion/LiPo), and I will be covering that in a later tutorial.

But the motor will probably run fine with 7 or 8 volts :P

+Nicholas Jize unfortunately no, because when the train stops there is 0volts, so the arduino will turn off.

Arduino uses about 25mA and the power bank I use is 2500mAh, so approximately 1000hours. Of course, LEDs and sensors will drop this time significantly, as will power bank efficiency. Still, it will last a lot longer than the AAA batteries in the train!

where it says: if (distance < 16) { delete the next two lines, and type in: lego.SingleOutput(0, PWM_FLT, BLUE, CH1); and in the else section (where it says Serial.print(distance) etc, add the line: lego.SingleOutput(0,PWM_FWD4, BLUE, CH1); You can then delete all references to "counter", the void changeDirection, the trigPinBack and echoPinBack sections, to make your code much smaller.

#include LEGOPowerFunctions lego(6); #define trigPinFront 5 #define echoPinFront 4 byte TrigPin = 5; byte echoPin = 4; void setup(){ Serial.begin (9600); pinMode(trigPinFront, OUTPUT); pinMode(echoPinFront, INPUT); } void loop() { long duration, distance; digitalWrite(trigPinFront, LOW); delayMicroseconds(2); digitalWrite(trigPinFront, HIGH); delayMicroseconds(10); digitalWrite(trigPinFront, LOW); duration = pulseIn(echoPin, HIGH); distance = (duration/2) /29.1; if(distance < 16){ lego.SingleOutput(0, PWM_FLT, BLUE, CH1); } if (distance >= 200 || distance

I don't really understand what you are trying to do. How do you have the L298 connected?

Its an L298P shield v1.2..I strip the motor wire,connecting it to the motor driver

So in this case, you just follow the code from Tutorial 4. You do not need to use power functions library at all, because you are not using InfraRed.

+Michal Pietrzak it's possible but not stable, especially with these sensors. I will show how to do it on the next video.

Ale dlaczego?

+Michal Pietrzak power output to arduino and motors at the same time is not smooth, so power to sensors becomes unstable which means the code stops working. With LEDs instead of ultrasonic sensors it is not such a problem, but IR leds do not work as long range distance sensors.

What about big capacitor

Maybe you can try :) I just make simplest solution for beginners

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