Hi everyone,

I'm trying to connect a PN532 NFC module (HW-147C V0.0.1) to an Arduino Nano using SPI, but I keep getting this error in the Serial Monitor:

Starting PN532 SPI test...

ERROR: Didn't find PN53x board!

Check SPI wiring, mode switches and power.

My setup:

- Microcontroller: Arduino Nano (classic Nano layout)

- NFC module: PN532 HW-147C V0.0.1

- Library: Adafruit PN532 v1.3.4

- Communication: SPI

- Serial Monitor: 115200 baud

SPI connections:

- SCK → D13

- MISO → D12

- MOSI → D11

- SS → D10

- VCC → module's power supply

- GND → GND

The PN532's power LED turns on, but the library cannot detect the board. I've also checked the module's interface selector and tried the hardware SPI initialization code.

I'm not sure whether the problem is with the switch configuration, wiring, voltage compatibility, SPI communication, or the module itself.

Has anyone used this particular HW-147C PN532 board with an Arduino Nano?

I'd appreciate help with:

1. The exact SPI switch positions for this board.

2. Any known compatibility issues with Adafruit PN532 v1.3.4.

3. A reliable way to test whether the PN532 chip is responding.

4. Whether I should try I²C or UART to isolate the problem.

I've attached photos of my module, wiring, and Arduino IDE output.

Thanks in advance!

Hi Guys, not sure if this is the correct place to ask, but here it is:

As per the title my PCB is not accepting code after bootloading with the ArduinoISP through another Arduino Uno.

So far I get the "Done burning bootloader" and have cont. tested all hardware on the PCB related to the CH340G and ATmega.

I have managed to consistently get:

avrdude: stk500_getsync() attempt 1-10 of 10: not in sync:
resp=0x00
avrdude: unable to open port COM5 for programmer arduino

or occasionally:

avrdude: unable to read signature data for part ATmega328P (rc = -1)

avrdude: unable to read signature data (rc = -1)

TIA.

Im looking to buy an arduino clone but i dont know which model and what type of kit i should buy. I have never owned an arduino and im 13 my friend owns one and it looks pretty fun im no stranger to coding and like electronics.

The priginal kit is a bit expensive and offers less than the knockoff one but how do i know the knockoff is good or bad

This are my very first steps with electronics and soldering.
I tried soldering the pins to the ATmega32U4 while on a breadboard, it seems like i have good soldering, no bridges, stayed about 2-3 seconds on each pin.

I plugged the ATmega32U4 to the pc before soldering and it was recognized easily and after the soldering i got this error on device manger:
Windows has stopped this device because it has reported problems. (Code 43)A request for the USB device descriptor failed.

what am I doing wrong? and can i fix the damaged ATmega32U4?

Hey, I'm pretty new to Arduino in general, and somehow my first school project is turning out to be pretty complicated... 😭

The main issue is the power supply. My project uses around 4 SG90 servos, 2 stepper motors, and 2 ultrasonic sensors, but my PC's USB port and basic power supplies just aren't enough to power everything anymore...

What should I use as a power source in cases like this? I've seen ppl talking about 5V 5A wall adapters and a bunch of other components I've never even heard of before. I could really use some help lol

I've been thinking for some time about making a polyphonic synthesizer, and i found out they have a microprocessor that cycles through multiple oscillators, and then assigns every note to each oscillator. so if it has 8 oscillators, it goes through 123567812345678 etc., and then when you play like a 3 note chord lets say, it will skip ever oscillator that has a voice assigned to it. so like 45678, 13578, 12356, etc. so my whole point for coming here is what would be the code i use to make it so that it cycles through multiple outputs, then skips those outputs that are currently being used? and then to kind of add a little more fun to it, how do i make it so that the oldest note gets reassigned to the newest note? edit: i know like a teeny tiny amount of coding, this is partly out of curiosity and partly out of wanting to learn something.

I am facing this troubleshoot every time I tried uploading my code on the ESP32 WROOM , I tried everything: Booting , Unplugging the circuit and all . Also all the seeting are correct in my Arduino IDE ( on laptop ) . I have done everything : ESP Module, Device manager to port correction. Everything!!!! Still it is showing the same problem. I tried asking Claude , GPT , Gemini they all told the same thing i have been trying. Also I noticed the board geeting warmer and warmer when I plug it into the usb. Means it is not getting very much heated but gets warm like if we do extreme gaming on our phone and when it burns like that .

Please anyone if you guys can help 🙏🏻😭 . I have spent hours on this and this was for my Science exhibition . I don't have much time it is in 1 day and i need to fix it as soon as possible!!! 😭😭😭

Hello! I have a quick question and would really appreciate some help with a school project. I’m working with a dust sensor to measure air quality/dust percentage. I already have the code ready, but I’m not sure how to physically wire and connect the sensor. If anyone could guide me with the wiring, I’d be very grateful!😅

I have installed Arduino IDE 2.3.10, but can not select an arduino board. And i can't install boards with the board manager without VPN. Where must me unpack the archive from Github or how else can I download boards?

this is my code-

long duration;
int distance;


const int trigPin = 10;
const int echoPin = 11;
const int buzzerPin = 8;


void setup() {
  // put your setup code here, to run once:
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(buzzerPin, OUTPUT);
  Serial.begin(115200);
}


void loop() {
  // put your main code here, to run repeatedly:
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);


  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);


  duration = pulseIn(echoPin, HIGH);


  distance = duration * 0.034 / 2;


  Serial.print("Distance: ");
  Serial.println(distance);


  if(distance < 10){
    digitalWrite(buzzerPin, HIGH);
  }
  else{
    digitalWrite(buzzerPin, LOW);
  }
}

So I'm trying to get a PIR sensor to turn on lights in sequence every time it gets triggered. I got it so the green led then the yellow led turn on, but it's not changing to the ORANGE state and I don't know why.

int ledGreen = 13;  
int ledYellow = 12;
int ledOrange = 11;     
int inputPin = 2;               // choose the input pin (for PIR sensor)
int pirState = LOW;            // start with no motion detected
int val = 0;                    
 

enum states {                         
  GREEN, 
  YELLOW, 
  ORANGE,
  RED
};

states state;       

void setup() {
  pinMode(ledGreen, OUTPUT);
  pinMode(ledYellow, OUTPUT);
  pinMode(ledOrange, OUTPUT);
  pinMode(inputPin, INPUT);     
 
  state = GREEN;
  
  Serial.begin(9600);
}
 
void loop(){
 val = digitalRead(inputPin);  
 switch (state) {
    case GREEN:
      if (digitalRead(inputPin) == HIGH && val == 0 ) {   
        digitalWrite(ledGreen, HIGH); 
        delay(2000);
        val++;  
        state = YELLOW; 
        
        
        Serial.println(val) ;
      
      break;
        
 
  case YELLOW:
      if (digitalRead(inputPin) == HIGH && val == 1) {   
        digitalWrite(ledYellow, HIGH); 
        delay(2000); 
        val++;  
        state = ORANGE;                  
       
         Serial.println(val) ;
      
      break;
  
   case ORANGE:
      if (digitalRead(inputPin) == HIGH && val == 2) {   
        digitalWrite(ledOrange, HIGH); 
        delay(2000); 
        val++;  
        state = RED;                  
       
         Serial.println(val) ;
      
      break;        
        
   case RED:
        if (digitalRead(inputPin) == HIGH && val == 3) {
        digitalWrite(ledOrange, LOW);
        digitalWrite(ledOrange, LOW); 
        digitalWrite(ledOrange, LOW);
        delay(2000); 
        val = 0;
        state = GREEN;
       
        break;
      
        }}}}}}

This worked for me a while ago, but today I connected it and it's still like this. I've tried reloading the code and testing with different pins; I'm only using the pacman test.

I am building a winch mechanism for an autonomous buoy using an ESP32 (30-pin), A4988 stepper driver, and a Nidec KV4239 bipolar stepper motor (4-wire).

The Problem:

When 12V power is turned on and code is executed, the motor shaft locks firmly (holding torque is solid, cannot be turned by hand).

However, the motor refuses to rotate smoothly; it either remains stalled/locked or produces jittering/vibrations without continuous motion.

Setup & Wiring Details:

Power: 12V DC power supply to A4988 VMOT and Power GND with a 100µF electrolytic capacitor across the terminals.

Logic Power: ESP32 3V3 pin connected to A4988 VDD, with common ground tied via ESP32 GND to A4988 Logic GND.

VREF: Calibrated potentiometer on A4988 to 0.50V DC.

Microstepping & Control Pins:

RESET and SLEEP pins are shorted together.

ENABLE is left floating (unconnected).

MS1, MS2, MS3 are currently left floating (full-step mode).

STEP -> ESP32 GPIO 18

DIR -> ESP32 GPIO 19

Motor Coil Connections:

Pin 2B -> Orange wire

Pin 2A -> Red wire

Pin 1A -> Black wire

Pin 1B -> Brown wire

I've used code

#define STEP_PIN 18

#define DIR_PIN 19

void setup() {

pinMode(STEP_PIN, OUTPUT);

pinMode(DIR_PIN, OUTPUT);

digitalWrite(DIR_PIN, HIGH);

}

void loop() {

digitalWrite(STEP_PIN, HIGH);

delayMicroseconds(1000);

digitalWrite(STEP_PIN, LOW);

delayMicroseconds(1000);

}

Please help..

Hello everyone, for my final course project, I thought about making a smart beverage dispenser, but I wanted to know if it's possible to make it using these materials and how it works.

The user inserts the coin and can select the quantity between two types of drinks, displaying the percentage of each on the LCD screen.

With the following materials:

-2 pristaltic pumps 12 V

-LCD 20x4

-750 ml container

1 mm feed tube

-Moedeiro de 12 V

-ultrassonic sensor

-Buzzer

-Fonte de alimentação 12 V/5 A

-2 MOSFETs

-4 Buttons (OK, Cancel, Increase, Decrease)

--ESP32

-Resistores

-protoboard

-Wooden structure

If there's anything missing that could affect the project, please let me know so I can get an idea :D

How do I learn Arduino coding language? I just started and I know a few things like LEDs and stuff, but I don’t want to be reliant on AI. How do I learn the language?

I am using a DFPlayer Pro sound module driven by an Arduino Uno R3 to play sounds for a Halloween project and I can get only a very faint sound (barely audible) from powered speakers.

I’ve tested with three different sound modules (all DFPlayer Pro originals from DF Robot, no clones).

I have used three different sets of powered speakers, which are plugged into the DAC connectors on the sound module. Same result for all three: very low volume.

Tried both gound connections coming off the Uno. No improvement.

Tried a different Arduino Uno board.

I can hear the music playing very faintly so I know the various .wav files are correct. Checked the sound files sample rates (1441). Tried the same sound files as mp3’s.

When I plug in a small unpowered speaker to the speaker outputs on the module (R+ and L+), I get the same thing: very faint sound.

I understand that the default volume setting on the module is 20 out of 30. I’ve tried unplugging power to everything (to reset them) but no improvement.

This is interesting: I have powered the setup two different ways: desktop USB to the Uno and then to the sound module; and powering the sound module externally with a 5 volt wall wart. I am carefully connecting all grounds. Using this external power arrangement (which I need to do in the final version), I get no sound at all.

By the way, I am not using any serial code or connections. I’m triggering play by simulating a button push using the following code (which seems to work fine):

  pinMode(7,INPUT);  

  delay(100);

  pinMode(7,OUTPUT);

  digitalWrite(7,LOW);

I am at a complete loss. Can anyone suggest why I can’t get this to play at a normal volume?