All is okay but wheels not turning/spinning/rotating - self balancing robot

Hi, I'm a newbie in Arduino and have searched the issue in this web but I didn't find any related to my problem (or, I missed one).
All is okay means that I assemble self balancing robot based on this following diagram and has plug all and serial monitor shows that it works. But WHEELS not rotating at all.

(This time, I plugin power from my old notebook).

Don’t see any wires to the PWM pins. (enable A and B)

What is the battery voltage ?

1 Like

sorry, late to answer. really glad. owh yes. 9 volt. Beside that I open the jumper (enA and enB). When I close the jumpers. The red led turn off.

From the code I see that it only enables 4 pinoutsL 11,10,9,6 ( based on the circuit diagram above)

Hi, @joe_kdw
Welcome to the forum.

What is your 9V supply, hopefully not a PP3 smokedetector battery, that will not have the power you need.

Can you please post your code? (Using code tags)
To add code please click this link;

Can you post an image(s) of your project so we can see your component layout?
Do you have a DMM?

Thanks.. Tom... :smiley: :+1: :coffee: :australia:

  1. Here's the code:
#include "I2Cdev.h"
#include <PID_v1.h> //From
#include "MPU6050_6Axis_MotionApps20.h" //

MPU6050 mpu;

// MPU control/status vars
bool dmpReady = false;  // set true if DMP init was successful
uint8_t mpuIntStatus;   // holds actual interrupt status byte from MPU
uint8_t devStatus;      // return status after each device operation (0 = success, !0 = error)
uint16_t packetSize;    // expected DMP packet size (default is 42 bytes)
uint16_t fifoCount;     // count of all bytes currently in FIFO
uint8_t fifoBuffer[64]; // FIFO storage buffer

// orientation/motion vars
Quaternion q;           // [w, x, y, z]         quaternion container
VectorFloat gravity;    // [x, y, z]            gravity vector
float ypr[3];           // [yaw, pitch, roll]   yaw/pitch/roll container and gravity vector

/*********Tune these 4 values for your BOT*********/
double setpoint= 176; //set the value when the bot is perpendicular to ground using serial monitor. 
//Read the project documentation on to learn how to set these values
double Kp = 21; //Set this first
double Kd = 0.8; //Set this secound
double Ki = 140; //Finally set this 
/******End of values setting*********/

double input, output;
PID pid(&input, &output, &setpoint, Kp, Ki, Kd, DIRECT);

volatile bool mpuInterrupt = false;     // indicates whether MPU interrupt pin has gone high
void dmpDataReady()
    mpuInterrupt = true;

void setup() {

  // initialize device
    Serial.println(F("Initializing I2C devices..."));

     // verify connection
    Serial.println(F("Testing device connections..."));
    Serial.println(mpu.testConnection() ? F("MPU6050 connection successful") : F("MPU6050 connection failed"));

    // load and configure the DMP
    devStatus = mpu.dmpInitialize();

    // supply your own gyro offsets here, scaled for min sensitivity

      // make sure it worked (returns 0 if so)
    if (devStatus == 0)
        // turn on the DMP, now that it's ready
        Serial.println(F("Enabling DMP..."));

        // enable Arduino interrupt detection
        Serial.println(F("Enabling interrupt detection (Arduino external interrupt 0)..."));
        attachInterrupt(0, dmpDataReady, RISING);
        mpuIntStatus = mpu.getIntStatus();

        // set our DMP Ready flag so the main loop() function knows it's okay to use it
        Serial.println(F("DMP ready! Waiting for first interrupt..."));
        dmpReady = true;

        // get expected DMP packet size for later comparison
        packetSize = mpu.dmpGetFIFOPacketSize();
        //setup PID
        pid.SetOutputLimits(-255, 255);  
        // ERROR!
        // 1 = initial memory load failed
        // 2 = DMP configuration updates failed
        // (if it's going to break, usually the code will be 1)
        Serial.print(F("DMP Initialization failed (code "));

//Initialise the Motor outpu pins
    pinMode (6, OUTPUT);
    pinMode (9, OUTPUT);
    pinMode (10, OUTPUT);
    pinMode (11, OUTPUT);

//By default turn off both the motors

void loop() {
    // if programming failed, don't try to do anything
    if (!dmpReady) return;

    // wait for MPU interrupt or extra packet(s) available
    while (!mpuInterrupt && fifoCount < packetSize)
        //no mpu data - performing PID calculations and output to motors     
        //Print the value of Input and Output on serial monitor to check how it is working.
        Serial.print(input); Serial.print(" =>"); Serial.println(output);
        if (input>150 && input<200){//If the Bot is falling 
        if (output>0) //Falling towards front 
        Forward(); //Rotate the wheels forward 
        else if (output<0) //Falling towards back
        Reverse(); //Rotate the wheels backward 
        else //If Bot not falling
        Stop(); //Hold the wheels still

    // reset interrupt flag and get INT_STATUS byte
    mpuInterrupt = false;
    mpuIntStatus = mpu.getIntStatus();

    // get current FIFO count
    fifoCount = mpu.getFIFOCount();

    // check for overflow (this should never happen unless our code is too inefficient)
    if ((mpuIntStatus & 0x10) || fifoCount == 1024)
        // reset so we can continue cleanly
        Serial.println(F("FIFO overflow!"));

    // otherwise, check for DMP data ready interrupt (this should happen frequently)
    else if (mpuIntStatus & 0x02)
        // wait for correct available data length, should be a VERY short wait
        while (fifoCount < packetSize) fifoCount = mpu.getFIFOCount();

        // read a packet from FIFO
        mpu.getFIFOBytes(fifoBuffer, packetSize);
        // track FIFO count here in case there is > 1 packet available
        // (this lets us immediately read more without waiting for an interrupt)
        fifoCount -= packetSize;

        mpu.dmpGetQuaternion(&q, fifoBuffer); //get value for q
        mpu.dmpGetGravity(&gravity, &q); //get value for gravity
        mpu.dmpGetYawPitchRoll(ypr, &q, &gravity); //get value for ypr

        input = ypr[1] * 180/M_PI + 180;


void Forward() //Code to rotate the wheel forward 
    Serial.print("F"); //Debugging information 

void Reverse() //Code to rotate the wheel Backward  

void Stop() //Code to stop both the wheels
  1. Circuit diagram

NB: I use 9v Eveready :slight_smile: (Should I use 18650 battery?)
It should work when the robot connected to the notebook, but It shows nothing ... DMP works successfully and Serial Monitor (COM4) gives me clear how MPU6050 reacts when I tilt the robot but wheels never turn at all.

Here's what com4 says to me:

Here's how my project looks like :slight_smile:

Try adding enable A and B PWM CONTROL.

1 Like

Ehm ... The wheels .... turns hihihi .. thanks. SOLVED.
But, please, explain me why should enable them both since there's no instruction in that code. I see no command to enable it. Thanks

Now, time's to .... Kp. Ki and Kd ... SOLVED !!!!
By the way, in COM4 I see "FIFO Overflow". And, the wheels stop spinning. I use all needed libraries, as in:

#include "I2Cdev.h"
#include <PID_v1.h> //From
#include "MPU6050_6Axis_MotionApps20.h" //

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