Two motors of different types operated by switch

Projects Discussion and Showcase Robotics
1

Hello friends,

I am trying out a simple project as a learning tool to help me develop something more complicated in the future and have been greatly successful on my own thus far arriving at a halting point in the final stage of the prototype.

The design is quite simple: an Uno R3 and a L298n to operate a small 3v dc motor , i've programmed a servo motor to operate 245 degrees just prior to the 3v dc motor turning on, and this is all delay activated by a limit switch, so...

when the limit switch is released a 2 second delay before the servo operates, then another 2 second delay before the 3v motor engages, a 2 second delay and the dc motor shuts off and 2 seconds later the servo returns to zero degrees.

i am powering the L 298n using 8 AA batteries for 12volts, & using the arduino to power the servo thru a bread board and a 220uF capacitor.

While plugged into any AC outlet the project prototype operates exactly as desired, however when i attempt to power the arduino with a 9v battery, the servo does not respond as coded and the dc motor does not engage at all...

I would appreciate any help or feedback the group has to offer..

2

Is it a PP3 by any chance ?

3

I am not familiar with PP3?

it is a 5400 mAh 6F22 9v lithium ion rechargeable battery...

4

Keep the servo power seperate, use a different 9V battery for the UNO and the 8AA for just the servo.

5

I am powering the L298n with the 8AA to drive the DC motor; and the 9v to power the arduino. I am using jumper wires to connect to bread board the 5v and ground respectivly to the 220uF capacitor, and then to the servo.
Ive tried powering the servo directly with 9v thru the capacitor in which case the servo spins 360 continuously

6

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7

Then it is not a servo, you cannot control its angle only its speed and direction of rotation and powering it with 9V may well have damaged it depending on its specification

How did you do that ?

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8

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Please note that in the schematic I am unable to use an L298n only the L293 _ Ive used the pinout on the 293 as I would have for the L298n - other than that it is exactly the diagram ive created.

#include <ezButton.h>
#include <Servo.h>
int enA = 9;
int in1 = 8;
int in2 = 7;

ezButton limitSwitch(6);
Servo servo_1;

void setup() {
  Serial.begin(9600);
  servo_1.attach(10);
  limitSwitch.setDebounceTime(50);
  pinMode(enA, OUTPUT);
  pinMode(in1, OUTPUT);
  pinMode(in2, OUTPUT);
 servo_1.write(0);
}

void loop() {
  limitSwitch.loop();  
  if(limitSwitch.isReleased())

{ 
  delay(2000);
  servo_1.write(245);
  delay(2000);
  analogWrite(enA, 255);
   digitalWrite(in1, HIGH);
   digitalWrite(in2, LOW);
   delay(2000);
   analogWrite(enA, 0);
   delay(2000);
   servo_1.write(0);
}  
else if (limitSwitch.isPressed()) 
{ analogWrite(enA, 0);
  digitalWrite(in1, LOW);
  digitalWrite(in2, LOW);
}
}
9

  • Never power inductive loads and or motors from the Arduino 5v pin.

  • Please add the power supply connections to your driver/motor circuit.

  • servo_1.write(245); most hobby servos only can go from 0 to 180°

1 Like
10

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I was unable to correctly show how I power the Arduino with the 9 volt battery, it is a 9v adapter that plugs into the AC power jack on the arduino board itself.

The servo is a MG90S which i understood to be a 360 servo motor;
to clarify - if i plug the arduino into the wall and power the L298nn motor driver with the 18v from the AA batteries while powering the servo motor from the breadboard that i have connected to the 5v pin on the arduino - EVERYTHING WORKS with the code ive previously attached. The servo waits , then opens 245 degrees, then the dc motor begins to spin for a few seconds before shutting off the the servo reverses from 245 degrees back to zero.
The issue is when i try to power the arduino board with a 9v and the appropriate plug , the servo operates, but does not wait, and before the dc motor turns on the servo reverses its direction.

11

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When I try to power the servo motor in this way, upon recieving the signal it turns on and rotates continuously in one direction 360 with out stopping or reversing.