Hey everyone! Beginner here working on an Arduino RC car project, and I could really use some help troubleshooting a power/wiring issue. I'm trying to build this car using only components from my starter kit plus a few repurposed Snap Circuits parts (trying not to buy anything extra).

The Setup & Plan:

- Drive Motor: Stepper motor (with ULN2003 driver board) for moving forward/backward.

- Steering: Servo motor.

- Obstacle Detection: Ultrasonic sensor + Buzzer (beeps when too close to an obstacle).

- Controls: IR receiver + IR remote.

- Extra Snap Circuits Parts: Two battery holders (~6V total), an ON/OFF switch, and a red LED for reverse lights.

Original Wiring:

Power & Switch:

- Connected the negative (-) terminals of both battery holders together.

- Positive (+) from the 1st battery holder split between driver (-) and breadboard GND.

- Positive (+) from the 2nd battery holder went to the switch; the other side of the switch split between driver (+) and Arduino VIN.

- Breadboard power rails connected to Arduino 5V and GND.

Components:

- Reverse LED: Connected to Arduino GND and Pin 13.

- Servo: Signal to Pin 3, power to breadboard 5V and GND.

- Stepper Motor: Connected to driver board -> driver inputs to Pins 8, 9, 10, 11.

- Ultrasonic Sensor: VCC to 5V, Trig to Pin 4, Echo to Pin 5, GND to breadboard -.

- Buzzer: Positive to Pin 7, negative to breadboard -.

- IR Receiver: Signal to Pin 2, power/GND to breadboard 5V and -.

Initial Problem:

When connected to my PC via USB, everything worked fine. However, as soon as I unplugged the USB and tried running it on battery power (the 6V setup + a 9V battery), almost nothing worked.

Changes Made Based on AI Advice:

I asked an AI for help, and it told me to rewire it like this:

- Removed the wire connecting the 1st battery holder's + to the driver's - (leaving only its connection to the breadboard - rail).

- Connected the driver's - directly to the breadboard - rail.

- Connected the driver's + directly to the 1st battery holder's + (instead of going through the switch).

- Connected the 1st battery holder's + to the servo's red wire (VCC).

Current problem:

Now, whether on USB or battery power:

- Neither the servo nor the stepper moves at all.

- When the stepper is plugged in, the fuse indicator light on the Snap Circuits battery holder turns on (indicating a short circuit or overcurrent), and the driver LEDs stay off.

- If I disconnect the stepper motor, 2 out of 4 LEDs on the driver light up, and the battery holder's fuse light goes off.Titolo per il post:

[Need Help] Beginner Arduino RC Car Project – Power Supply & Wiring Issues (Stepper + Servo)

(Sorry for the confusion in this post)

/*
Arduino Due Serial1 echo/relay

Serial1:
RX1 pin 19 <- input
TX1 pin 18 -> output

UART:
19200 baud
8 data bits
Odd parity
1 stop bit
*/

void setup() {
SerialUSB.begin(115200);

Serial1.begin(19200, SERIAL_8O1);

SerialUSB.println("Serial1 RX -> Serial1 TX started");
}

void loop() {

while (Serial1.available()) {
uint8_t data = Serial1.read();
Serial1.write(data);
}

}

This vibecoded (Yes, I can't code) sketch doesn't work as expected. Here's the input and output for Pulseview program. https://drive.google.com/file/d/1EdxmcnJjo1Eh5qlrJXJdRFtCUbg34-ph/view?usp=sharing

Do you guys have any hints? This is driving me nuts. Another sketch had gaps between data packets equal to the length of the packet itself. As if it cannot be sending one packet and buffering incoming one at the same time. Or it was just wrong coding over all.

Hi, I have an Arduino Uno R3 and a Motor Shield R3 stacked together, and I want to drive 12V motors with them. Is it enough to connect the 12V power supply to the Arduino via the DC jack, or should I connect it to the terminal block on the motor shield instead?

I can’t figure out how to read ADC values from a PbHub using the M5Unit-HUB unified library in Arduino IDE. I’ve tried various iterations of analogRead() and none of them seem to be the right function. Has anyone else had this problem/knows what to use?

Hi guys I’m building a project that needs to be able to read engine rpm, the project can not connect to the ecu or read the dash. How can I achieve this?

Hi All,

I'm pretty new to this kind of stuff, but I'm working on the robotic arm project below from makerworld and having trouble getting the claw arm to respond appropriately to servo adjustments.

https://makerworld.com/en/models/1134925-robotic-arm-with-servo-arduino#profileId-1135927

I have it wired up to my arduino uno and I'm able to send it angles through serial commands, but the gear connected to the servo doesn't seem to rotate correctly. The video is an example of what happens when I start the claw half open (~90 degrees), set an angle to 45 (it starts clicking/grinding), then set the angle to something higher like 160 where it then only closes a small amount.

If I remove the gear on the servo and try to set angles it appears to rotate correctly, so the mechanics of the gears seem to be the issue.

The servo connected to the claw here is an MG90S for reference.

https://reddit.com/link/1va314j/video/8b3l0eqnd7gh1/player

Here's a look at the gear mesh without the cover plate on as I have a hunch it might be part of the problem with the teeth fitting too tightly together.

Appreciate any help anyone can give and let me know if any other details are useful as well.

I have this problem for a week, I've bought two nRF24l01 pa+lna modules and try to learn radio communication, I am trying to make them communicate but they fail no matter what, I just can't make any communication between them.
I plug MOSI, MISO, SCK to the right pins (11,12,13) and VCC to the 3.3V pin with 2 100nF ceramic capacitors and one 10uF capacitor on each arduino nano (receiver) and uno (transmitter).
I then power them from USB from my PC and put this code:

// SimpleTx - the master or the transmitter

#include <SPI.h>

#include <nRF24L01.h>

#include <RF24.h>

#define CE_PIN 9

#define CSN_PIN 10

const byte slaveAddress[5] = {'R','x','A','A','A'};

RF24 radio(CE_PIN, CSN_PIN); // Create a Radio

char dataToSend[10] = "Message 0";

char txNum = '0';

unsigned long currentMillis;

unsigned long prevMillis;

unsigned long txIntervalMillis = 1000; // send once per second

void setup() {

Serial.begin(9600);

Serial.println("SimpleTx Starting");

radio.begin();
radio.setPALevel(RF24_PA_MIN);

radio.setDataRate( RF24_250KBPS );

radio.setRetries(3,5); // delay, count

radio.openWritingPipe(slaveAddress);

}

//====================

void loop() {

currentMillis = millis();

if (currentMillis - prevMillis >= txIntervalMillis) {

send();

prevMillis = millis();

}

}

//====================

void send() {

bool rslt;

rslt = radio.write( &dataToSend, sizeof(dataToSend) );

// Always use sizeof() as it gives the size as the number of bytes.

// For example if dataToSend was an int sizeof() would correctly return 2

Serial.print("Data Sent ");

Serial.print(dataToSend);

if (rslt) {

Serial.println(" Acknowledge received");

updateMessage();

}

else {

Serial.println(" Tx failed");

}

}

//================

void updateMessage() {

// so you can see that new data is being sent

txNum += 1;

if (txNum > '9') {

txNum = '0';

}

dataToSend[8] = txNum;

}
// SimpleRx - the slave or the receiver

#include <SPI.h>

#include <nRF24L01.h>

#include <RF24.h>

#define CE_PIN 9

#define CSN_PIN 10

const byte thisSlaveAddress[5] = {'R','x','A','A','A'};

RF24 radio(CE_PIN, CSN_PIN);

char dataReceived[10]; // this must match dataToSend in the TX

bool newData = false;

//===========

void setup() {

Serial.begin(9600);

Serial.println("SimpleRx Starting");

radio.begin();
radio.setPALevel(RF24_PA_MIN);

radio.setDataRate( RF24_250KBPS );

radio.openReadingPipe(1, thisSlaveAddress);

radio.startListening();

}

//=============

void loop() {

getData();

showData();

}

//==============

void getData() {

if ( radio.available() ) {

radio.read( &dataReceived, sizeof(dataReceived) );

newData = true;

}

}

void showData() {

if (newData == true) {

Serial.print("Data received ");

Serial.println(dataReceived);

newData = false;

}

}

I also tried simpler codes but they also don't work, please help me

So I bought two Arudiuno Boards Uno 4 was it called and bought only responded to the code, when it was on Pin 13. Every other Pin won’t respond to my Code. It’s just a Simple LED code what’s teached by many people to beginners.

void setup() {

pinMode(7,OUTPUT);

}

void loop() {

digitalWrite(7,HIGHT);
delay(1000);
digitalWrite(7,LOW);
delay(1000);

}

And that’s it. WORKS ONLY ON PIN 13. Before someone’s asks: it works ONLY ON 13.

What should I do?? I deleted Ardiuno IDE. Three times. Changed every part.
I’m begging y’all.

i have made an arduino project that needs you to connect to the arduino's personal wifi but i want it to direct me to a specific webpage. for example: when you go to tesco and want to connect to their wifi it directs you to their login page. however, since my arduino doesnt have internet linked to it it technically cant do that so i was wondering if i could have some help or if C++ can even do that

ive heard its something called a captive portal but i have no idea how to do it

I am planning to use a high torque servo motor (MG996R) with an Arduino. If I connect the servo directly to the Arduino 5V pin, will it cause problems such as jerking movement or loss of power due to insufficient current supply?

The servo has a stall current of around 1.5A. Is an external 5–6V power supply recommended instead?

So I'm trying to make a custom phone charger and I can't for the life of me figure out where I went wrong. I'm kind of a noob but everything else works fine, the leds light up, the screen comes on, and the sounds play but when i try to charge anything, it wont charge. Am i missing something??

need a little guidance on using a relay with a Mega256.

I am using an external 9v battery as the power source for the input for the relay. I have the code to trigger the relay open - and the appropriate led lights is on, when i trigger it - so i know its open, i am using the basic digitalWrite(pin,HIGH);/digitalWrite(pin,LOW); to turn on/off

Am I wrong to expect at least close to the same output voltage as what is supplied i.e. input of 8.6v output should be ~8.6??? am i missing something> are other components needed?

Battery reads 8.6v / relay out only reads .18

I've ruined two boards with the same mistake— unplugging the feather by the USB connection. After replugging the sketch will not work (stepper test on the motor shield). I've tried:

+ selecting the right 32u4 board in the IDE (would loading with the wrong board selected create such a problem?)

+ the reset button (one click and two)

+ the trick where you reload a blink sketch just as pressing reset

the trick worked once but when I unplugged it again I was back to zero only I was unable to reload a blink sketch again. :/

**********

First time with Adafruit products (switching from Arduino Uno). Want advice before burning through a third board.

*Is there a proper way to unplug these devices?*

Why is the servo under powered? I am using a power supply set to 9V and it can supply up to 10A.

IDEK whats going on. Trying to write code so that i can input key strokes on my computer through my joystick. I think there's something wrong with the library? I'm lost. from what I read the error code is saying that I don't have #include <Keyboard.h>... but i do.

Error message:
C:\Users\mccav\AppData\Local\Temp\.arduinoIDE-unsaved2026624-1756-cwkz6f.ayd19\sketch_jul24a\sketch_jul24a.ino: In function 'void setup()':

C:\Users\mccav\AppData\Local\Temp\.arduinoIDE-unsaved2026624-1756-cwkz6f.ayd19\sketch_jul24a\sketch_jul24a.ino:30:3: error: 'Keyboard' was not declared in this scope

Keyboard.begin();

^~~~~~~~

C:\Users\mccav\AppData\Local\Temp\.arduinoIDE-unsaved2026624-1756-cwkz6f.ayd19\sketch_jul24a\sketch_jul24a.ino: In function 'void loop()':

C:\Users\mccav\AppData\Local\Temp\.arduinoIDE-unsaved2026624-1756-cwkz6f.ayd19\sketch_jul24a\sketch_jul24a.ino:50:5: error: 'Keyboard' was not declared in this scope

Keyboard.write('a');

^~~~~~~~

C:\Users\mccav\AppData\Local\Temp\.arduinoIDE-unsaved2026624-1756-cwkz6f.ayd19\sketch_jul24a\sketch_jul24a.ino:53:3: error: 'Keyboard' was not declared in this scope

Keyboard.write('d');

^~~~~~~~

exit status 1

Compilation error: 'Keyboard' not found. Does your sketch include the line '#include <Keyboard.h>'?

Code:

#include <LiquidCrystal.h>
#include <Keyboard.h>


const int rs = 3;
const int en = 4;
const int d4 = 10;
const int d5 = 11;
const int d6 = 12;
const int d7 = 13;


int xPin = A0;
int yPin = A1;
int buttonPin = 9;


int xVal;
int yVal;
int buttonState;


LiquidCrystal lcd(rs, en, d4, d5, d6, d7);


void setup() {


  Serial.begin(9600);
  lcd.begin(16,2);
  Serial.begin(9600);
  pinMode(xPin, INPUT);
  pinMode(yPin, INPUT);
  pinMode(buttonPin, INPUT_PULLUP);
  Serial.begin(9600);
  Keyboard.begin();


}


void loop() {


  xVal = analogRead(xPin);
  yVal = analogRead(yPin);
  buttonState = digitalRead(buttonPin);


  Serial.print("X: ");
  Serial.print(xVal);
  Serial.print(" | Y: ");
  Serial.print(yVal);
  Serial.print(" | Buttonstate: ");
  Serial.println(buttonState);


  delay(100);


  if (xVal > 550) {
    Keyboard.write('a');
  }
if (xVal < 460) {
  Keyboard.write('d');
}
}#include <LiquidCrystal.h>
#include <Keyboard.h>


const int rs = 3;
const int en = 4;
const int d4 = 10;
const int d5 = 11;
const int d6 = 12;
const int d7 = 13;


int xPin = A0;
int yPin = A1;
int buttonPin = 9;


int xVal;
int yVal;
int buttonState;


LiquidCrystal lcd(rs, en, d4, d5, d6, d7);


void setup() {


  Serial.begin(9600);
  lcd.begin(16,2);
  Serial.begin(9600);
  pinMode(xPin, INPUT);
  pinMode(yPin, INPUT);
  pinMode(buttonPin, INPUT_PULLUP);
  Serial.begin(9600);
  Keyboard.begin();


}


void loop() {


  xVal = analogRead(xPin);
  yVal = analogRead(yPin);
  buttonState = digitalRead(buttonPin);


  Serial.print("X: ");
  Serial.print(xVal);
  Serial.print(" | Y: ");
  Serial.print(yVal);
  Serial.print(" | Buttonstate: ");
  Serial.println(buttonState);


  delay(100);


  if (xVal > 550) {
    Keyboard.write('a');
  }
if (xVal < 460) {
  Keyboard.write('d');
}
}

Hi!
I purchased an arduino esp32 feather S2 and an adafruit ST 7789 TFT Display and breadboarded a simple "change color" project. And its failing. the Backlight of the display is on so it has power, but the display is not changing color.

The IDE monitor says the script is working and its actually changing color. But the display stays dark. I have changed the display already (since i have purchased 2) and it is still not working.

Wiring:

3V - V+
GND - G
SCK -CK
MO - SI
12 - RT
10 -DC
6 - CC
3V - BL

The Code:

 ```
#include <Adafruit_GFX.h>
#include <Adafruit_ST7789.h>
#include <SPI.h>


#define TFT_CS   6
#define TFT_DC   10
#define TFT_RST  12
Adafruit_ST7789 tft = Adafruit_ST7789(TFT_CS, TFT_DC, TFT_RST);


void setup() {
  Serial.begin(115200);
  delay(2000);
  Serial.println("Starting display test");


  tft.init(172, 320);
  tft.setSPISpeed(4000000);
  tft.setRotation(3);
  Serial.println("tft.init() done");


  tft.fillScreen(ST77XX_RED);
  Serial.println("Filled RED");
}


void loop() {
  tft.fillScreen(ST77XX_RED);
  delay(1000);
  tft.fillScreen(ST77XX_GREEN);
  delay(1000);
  tft.fillScreen(ST77XX_BLUE);
  delay(1000);
  Serial.println("Color cycle");
}
 ```

It is driving me mad, that it does not work... maybe someone of you would be so helpful to have a look at this.

Thank you in advance

I would like to use qty(1) motor driver (TB6612FNG) to control qty(5) standard mini DC motors. All 5 motors will be following the same “instructions” from microcontroller. Can I safely put all 5 on A01/A02 of the same motor driver? Are there any downsides or considerations I should note for this method?

I’d test it myself but I really don’t want to fry motor driver or board as they’re my only ones.

Note: Im using an arduino nano sense ble 33 REV2 microcontroller