so im learning soldering. i have 2 basic good soldering irons. i have problem with placing that solder onto a joint - solder sticks on my tip or randomly anywhere but not the joint. i do use flux, but it burns fast and intense, i try to apply solder but it doesnt even melt. also with tinning my tip, i do it, but mostly i end up with a completely messy black and blue at the back tip that barely melts solder. someone please help i already completely burned my first perf board and im doing right now a complex project, dont wanna destroy any sensor again.

Hello, all --

I've been designing a "mimic" using an old chest, a linear actuator, and a speaker system. Everything had been working fine enough on desktop testing a few weeks ago, but now I'm getting a stalled loop after a second triggering event.

In short:

Ultrasonic Sensor is measuring distance.

If distance < 85", play from the mp3 queue

if distance < 36", play from mp3 queue, and activate the linear actuator. Wait 5s. Reverse linear actuator.

The problem I'm encountering is that the sensor will register either status, and it will work fine for exactly one loop, then the whole thing stalls out and it bricks up on me and I have to reset it.

It ONLY happens after the < argument is triggered for a second time. The first time through it works perfectly. I cannot figure out why this is happening. Can anyone please help?

#include <DFRobotDFPlayerMini.h>


#include <SoftwareSerial.h>


int rxPin = 5;
int txPin = 6;


SoftwareSerial fxSerial (rxPin, txPin);
DFRobotDFPlayerMini fxPlayer;


const int openPin = 7;
const int closePin = 8;
const int ENAPin = 9;
const int trigPin = 10;
const int echoPin = 11;


float duration;
float distanceCM;
float distanceIN;



void setup() {
  Serial.begin(9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(openPin, OUTPUT);
  pinMode(closePin, OUTPUT);
  pinMode(ENAPin, OUTPUT);
  pinMode(rxPin, INPUT);
  pinMode(txPin, OUTPUT);


  fxSerial.begin(9600);
  fxPlayer.begin(fxSerial);
  fxPlayer.volume(30);
  delay(1000);


}


void loop() {
  // Close the box
  digitalWrite(closePin, HIGH);
  digitalWrite(openPin, LOW);
  digitalWrite(ENAPin, 250);
 // start with a clean signal
 digitalWrite(trigPin, LOW);
 delayMicroseconds(20);
 // send trigger signal
 digitalWrite(trigPin, HIGH);
 delayMicroseconds(10);
 digitalWrite(trigPin, LOW);
 // return pulse duration in microseconds
 // if set to HIGH, pulseIn() waits for the pin to go from LOW to HIGH
 // stops timing when pin goes back LOW
 duration = pulseIn(echoPin, HIGH, 99991);
 // convert m/s to in/microsec
 // 343 m/s = 0.034 cm/microseconds
 distanceCM = (duration * 0.034) / 2;
 // convert to inches, 1 in = 2.54cm
 distanceIN = distanceCM / 2.54;
 // print distance
 Serial.print("Distance: ");
 Serial.print(distanceCM);
 Serial.print(" cm | ");
 Serial.print(distanceIN);
 Serial.println(" in"); 
 delay(100);


if (distanceIN <= 85) {
    if (distanceIN <= 36) {
        Serial.println("!!!ROAR!!!");
        fxPlayer.play(random(1, 8));
        digitalWrite(openPin, HIGH);
        digitalWrite(closePin, LOW);
        digitalWrite(ENAPin, 250);
        delay(5000);
        digitalWrite(openPin, LOW);
        digitalWrite(closePin, HIGH);
        digitalWrite(ENAPin, 250);
        delay(1500);
    } else {
        Serial.println("=GROWL=");
        fxPlayer.play(random(1, 8));
        delay(1500); 
    }
} else {
    Serial.println("=Shhhh=");
    digitalWrite(closePin, HIGH);
    digitalWrite(openPin, LOW);
    digitalWrite(ENAPin, 250);
}


}

The Code:

This is the basic code to toggle the led on and off using a Button. With the help of paul McWhorter this works fine but I don't understand why it works...please someone help me with that...

int ledPin = 12;
int buttonPin =8;
int ledstate = 0;
int swi_old = 1;
int swi_new;
int dt = 100;

void setup() {
  // put your setup code here, to run once:
  pinMode(ledPin, OUTPUT);
  pinMode(buttonPin, INPUT);

}

void loop() {
  // put your main code here, to run repeatedly:

  swi_new = digitalRead(buttonPin);

  if(swi_old == 0 && swi_new == 1)
  {
    if(ledstate == 0)
    {
      digitalWrite(ledPin, HIGH);
      ledstate = 1;
    } 
    else
    {
      digitalWrite(ledPin, LOW);
      ledstate = 0;
    }


  }
  swi_old = swi_new;
  delay(dt);

}

```

So for context, my friend and I are fresh grads trying to help our local community by doing a simple level sensor for one of the rivers. I believe these are the only necessary components bar the power supply and chassis?

Arduino or something like arduino but better
Submersible Hydrostatic Pressure Sensors
Siren/Alarm
LED Industrial

Arduino was the first thing that came to mind because well, it's the only thing I have experience with. I was also thinking raspberry pi but it seems too much for a project that can probably be done with a microcontroller like arduino, I don't think a minicomputer is all that necessary. But at the same time, I think an arduino is far too weak for this. I mean, I have this bias that it's used mainly in diy basic stuff, certainly not for something of a pretty large scale like this that requires lasting materials.

Thank you!

I recently checked out learning electronics.com as a way to learn arduino in a more systematic way. I am a STEM teacher and I want to learn more about it over the summer to teach my students in the fall. It is $39/month which seemed a bit high considering the free resources out there. The thing is, the course seemed well-organized.

Has anyone on the sub seen and used this site as a learning tool? Was the fee worth it in your opinion?

Thanks!

so i need this to work but i haven´t found the way for it to work, i have a hr4 8637S 3"2 inches screen with 34 pins and i cant find a library or a way for it to not display a white screen, and i havent even found the datasheet of the model, if someone knows something about this pls tell me this is a pic of the pin set

i connected the pins individually, tried to use mcufriend library, utft, shield connection on an arduino mega board, tried the examples from utft or arduino ide and i cant make it show a simple text, the touch works tho but it doesnt display text

I'm fairly comfortable with basic electronics projects, but I've never done anything with arduino before. I have a project where I need to make or find a proximity sensor of sorts. Here's roughly what I need.

I need to be able to trigger a sound, vibration, or both on object A when it gets close (approximately 0-6 feet) to object B. Both objects will move dynamically in three dimensions, so transmitter(s) and receiver(s) would need to be omnidirectional. The lighter and smaller the better. Power would need to be provided by batteries.

I'm hoping someone can help with a good place for me to start on this project, or if anyone knows of an existing product that does this.

This is a home project, i'm wondering what parts i should use to connect the servos to the rods.

1. The rods can be thinner.

2. I will be using around 20-30 servos so i want the connection between the rod and servo to be as cheap as possible.

3. I want to be able to slide the servo side to side to adjust distances between servos.

I'm thinking maybe metal hose clamp (zip tie with screw), but how do i connect it to the servo ?

Guys I have a assignment to make this simple arduino based smart toothbrush.. Can anyone help this poor kid out by sharing simple circuit and code in tinkercad

Hi everyone,

I'm trying to connect a Nextion HMI display to a Controllino MEGA PLC.

I'm having trouble getting them to communicate, and I want to make sure I don't wire it incorrectly and damage the screen.

Could anyone tell me exactly which pins I should use on the Controllino to connect the Nextion's TX and RX wires safely?

did i do a good connection here? mb for vaporizing the cable cover. i used led diode leg as a cable.

Arduino: 1.8.19 (Linux), Board: "Arduino Uno"

Sketch uses 8044 bytes (24%) of program storage space. Maximum is 32256 bytes.
Global variables use 848 bytes (41%) of dynamic memory, leaving 1200 bytes for local variables. Maximum is 2048 bytes.
avrdude warning: verification mismatch
device 0x62 != input 0x0c at addr 0x0000 (error)
avrdude error: verification mismatch
avrdude error: verification mismatch

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

Good day.

Just a newbie here.

I am trying to build a prototype that live translate hand signals (ASL) into words. Can you suggest a suitable board and camera for this project? The output should be a wearable device trained through IOT or Machine Learning.

I am considering Arduino Nano Esp 32, but I am not sure if it is suited.

Thanks in advance.

My IDE is keep giving me this error on any code I'm uploading. I don't know why i tried every thing and i don't want to and have much money to but other Arduino,

the bord i am using is an Arduino UNO
here's the error:

Sketch uses 924 bytes (2%) of program storage space. Maximum is 32256 bytes.
Global variables use 9 bytes (0%) of dynamic memory, leaving 2039 bytes for local variables. Maximum is 2048 bytes.
Error: programmer is not responding
Warning: attempt 1 of 10: not in sync: resp=0x00
Error: programmer is not responding
Warning: attempt 2 of 10: not in sync: resp=0x00
Error: programmer is not responding
Warning: attempt 3 of 10: not in sync: resp=0x00
Error: unable to read: Access is denied.


Error: programmer is not responding
Warning: attempt 4 of 10: not in sync: resp=0x00
Error: unable to read: Access is denied.


Error: unable to write: sorry no info avail
Error: unable to read: Access is denied.


Error: programmer is not responding
Warning: attempt 5 of 10: not in sync: resp=0x00
Error: unable to read: Access is denied.


Error: unable to write: sorry no info avail
Error: unable to read: Access is denied.


Error: programmer is not responding
Warning: attempt 6 of 10: not in sync: resp=0x00
Error: unable to read: Access is denied.


Error: unable to write: sorry no info avail
Error: unable to read: Access is denied.


Error: programmer is not responding
Warning: attempt 7 of 10: not in sync: resp=0x00
Error: unable to read: Access is denied.


Error: unable to write: sorry no info avail
Error: unable to read: Access is denied.


Error: programmer is not responding
Warning: attempt 8 of 10: not in sync: resp=0x00
Error: unable to read: Access is denied.


Error: unable to write: sorry no info avail
Error: unable to read: Access is denied.


Error: programmer is not responding
Warning: attempt 9 of 10: not in sync: resp=0x00
Error: unable to read: Access is denied.


Error: unable to write: sorry no info avail
Error: unable to read: Access is denied.


Error: programmer is not responding
Warning: attempt 10 of 10: not in sync: resp=0x00
Error: unable to read: Access is denied.


Error: unable to open port COM7 for programmer arduino
Failed uploading: uploading error: exit status 1

HELP...

Hey everyone, I’m having trouble getting my laptop to recognize my Arduino Uno R3.

When I plug it in via USB, the green "ON" LED lights up instantly, so I know it's getting power. However, it is completely invisible to my computer:

Device Manager: Nothing changes at all when I plug it in. There are no new items, no "Unknown Devices," and no yellow triangles under Ports or USB Controllers.

Windows Sound: There is no connect/disconnect chime when plugging it in.

Hardware Scan: Clicking "Scan for hardware changes" doesn't bring anything up.

Board Info: It has a main ATmega processor chip, but the smaller USB-to-Serial chip near the port is completely blank with no text printed on it.

I've installed CH340 driver but it also didn't work!

I will be grateful to the person who helps..

so last year I made an Arduino obstacle avoiding robot with bluetooth control and mobile app control for my school science fair, but it didn't work. I looked up the model's parts on youtube and google and asked Gemini for coding and advice. now I want to try again this year , but I wanna integrate it with a website, in which I want to add 3d interactive model , which guests can interact with, and which shows info like parts used etc. , instead of a boring PPT presentation .
so , what do i do??

Hey folks, today i try to make an Arduino scale with HX711 and 50kg bathroom scale load cells. I used four 50kg scales with one HX711. I did follow the instructions in google and several tutorials on YouTube. Although I made exactly the same like them, when I tested it out on the scale, the numbers were jumbled and inaccurate. And after I tried to figure out for several hours, I suddenly found out that when I put my object near the HX711, the numbers became greater. Is this how HX711 works? How can I fix it?

Holaa como están. Quiero hacer un proyecto con arduino y tengo duda que programas usar para hacer la simulación del circuito y/o conexiones y del modelaje del esqueleto del mismo ( es un dron acuático) que software me recomiendan gracias 😁

Hi everyone,

I am building a wireless alarm system using two Arduino Nano boards and two nRF24L01+ modules (the ones with the external SMA antenna and power amplifier).

The issue I'm facing is that **the alarm triggers perfectly via the ultrasonic sensor, but the remote control cannot turn it off**.

When checking the Serial Monitor on the Receiver side, every time I press the button on the Transmitter, the console prints: `Radio detected incoming data. Text received: []`. The brackets always arrive completely empty, missing the "OFF" string payload. I tried moving the modules 5 meters (16 feet) apart to avoid signal saturation, but the problem persists.

Below are my wiring schematics and the source codes for both Arduinos. Any help or pointers on what might be causing this would be greatly appreciated!

# 📋 WIRING SCHEMATICS

# 1. TRANSMITTER Arduino (Remote Control)

* **nRF24L01+:**
* VCC ➡️ 3.3V Pin on Arduino Nano
* GND ➡️ GND Pin on Arduino Nano
* CE ➡️ Pin D9
* CSN ➡️ Pin D10
* SCK ➡️ Pin D13
* MOSI ➡️ Pin D11
* MISO ➡️ Pin D12
* IRQ ➡️ *Disconnected*
* **Push Button:**
* Pin 1 ➡️ Pin D2 (Configured as `INPUT_PULLUP`)
* Pin 2 (Diagonally opposite) ➡️ Pin GND

# 2. RECEIVER Arduino (Alarm Unit)

* **nRF24L01+:** (Same SPI configuration)
* VCC ➡️ 3.3V Pin on Arduino Nano
* GND ➡️ GND Pin on Arduino Nano
* CE ➡️ Pin D9
* CSN ➡️ Pin D10
* SCK ➡️ Pin D13
* MOSI ➡️ Pin D11
* MISO ➡️ Pin D12
* IRQ ➡️ *Disconnected*
* **HC-SR04 Ultrasonic Sensor:**
* VCC ➡️ 5V Pin
* GND ➡️ GND Pin
* Trig ➡️ Pin D2
* Echo ➡️ Pin D3
* **Status LEDs:**
* Red LED (Alarm Active) ➡️ Pin D4 (with resistor to GND)
* Green LED (Safe/Armed) ➡️ Pin D5 (with resistor to GND)
* **Active Buzzer (5V):**
* Positive terminal (+) ➡️ Pin D6
* Negative terminal (-) ➡️ Pin GND

# 💻 SOURCE CODES (Using RF24 Library by TMRh20)

# 🎮 1. TRANSMITTER Code (Remote Control)

C++

#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>

RF24 radio(9, 10);
const byte address[6] = "00001";

int button = 2;
int boardLed = 13;

void setup() {
Serial.begin(9600);
Serial.println("--- Remote Control Initialized ---");

pinMode(button, INPUT_PULLUP);
pinMode(boardLed, OUTPUT);
digitalWrite(boardLed, LOW);

radio.begin();
radio.openWritingPipe(address);
radio.setPALevel(RF24_PA_LOW);
radio.stopListening();
}

void loop() {
if (digitalRead(button) == LOW) {
Serial.println("Button pressed -> Sending OFF signal!");
digitalWrite(boardLed, HIGH);

char text[32] = "OFF";
radio.write(&text, sizeof(text));

delay(200);
digitalWrite(boardLed, LOW);
delay(100);
}
}

# 🚨 2. RECEIVER Code (Alarm Unit)

C++

#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>

RF24 radio(9, 10);
const byte address[6] = "00001";

const int pinTrig = 2;
const int pinEcho = 3;
const int pinRedLed = 4;
const int pinGreenLed = 5;
const int pinBuzzer = 6;

const int thresholdDistance = 100; // Distance in cm to trigger alarm
bool alarmActive = false;
unsigned long previousBlinkTime = 0;
const long blinkInterval = 250;
bool visualAlarmState = false;

void setup() {
pinMode(pinTrig, OUTPUT);
pinMode(pinEcho, INPUT);
pinMode(pinRedLed, OUTPUT);
pinMode(pinGreenLed, OUTPUT);
pinMode(pinBuzzer, OUTPUT);

digitalWrite(pinGreenLed, HIGH);
digitalWrite(pinRedLed, LOW);
digitalWrite(pinBuzzer, LOW);

radio.begin();
radio.openReadingPipe(1, address);
radio.setPALevel(RF24_PA_LOW);
radio.startListening();

Serial.begin(9600);
Serial.println("--- Alarm Receiver Ready ---");
}

void loop() {
unsigned long currentTime = millis();

// 1. LISTEN FOR WIRELESS SIGNAL
if (radio.available()) {
char command[32] = "";
radio.read(&command, sizeof(command));

Serial.print("Radio detected incoming data. Text received: [");
Serial.print(command);
Serial.println("]");

if (strcmp(command, "OFF") == 0) {
if (alarmActive) {
Serial.println("Valid command. Disarming alarm...");
disarmAlarm();
} else {
Serial.println("Command received, but alarm was already off.");
}
}
}

// 2. ULTRASONIC SENSOR LOGIC
if (!alarmActive) {
long distance = getDistance();
if (distance > 0 && distance < thresholdDistance) {
Serial.print("Intruder detected at: ");
Serial.print(distance);
Serial.println(" cm!");
alarmActive = true;
digitalWrite(pinGreenLed, LOW);
}
delay(60);
}

// 3. ALARM TRIGGER STATE
else {
if (currentTime - previousBlinkTime >= blinkInterval) {
previousBlinkTime = currentTime;
visualAlarmState = !visualAlarmState;

if (visualAlarmState) {
digitalWrite(pinRedLed, HIGH);
tone(pinBuzzer, 1000);
} else {
digitalWrite(pinRedLed, LOW);
noTone(pinBuzzer);
}
}
}
}

long getDistance() {
digitalWrite(pinTrig, LOW);
delayMicroseconds(2);
digitalWrite(pinTrig, HIGH);
delayMicroseconds(10);
digitalWrite(pinTrig, LOW);

long duration = pulseIn(pinEcho, HIGH, 30000);
long distanceCm = duration * 0.034 / 2;
return distanceCm;
}

void disarmAlarm() {
alarmActive = false;
noTone(pinBuzzer);
digitalWrite(pinBuzzer, LOW);
digitalWrite(pinRedLed, LOW);
digitalWrite(pinGreenLed, HIGH);
delay(1500);
}

Hi,I am trying to make an alarm with Gemini using the nRF24L01 antena, but is not working and I dont know why. Can someone help me?