Questions tagged [arduino-uno]

The Arduino Uno is the most common of the Arduino boards. It is based on the ATmega328P microcontroller.

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Serial available doesn't work right after upload

I have 2 programs to test serial communication, an simple arduino program that echoes whatever is on the serial port and a python program that writes to the serial port and prints the reply. I'm ...
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Change the baud rate of HC-05

#include <SoftwareSerial.h> SoftwareSerial BTSerial(10, 11); // RX | TX void setup() { pinMode(9, OUTPUT); // this pin will pull the HC-05 pin 34 (key pin) HIGH to switch module to AT mode ...
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How does the dual 5V and 3.3V output on the Uno R3 work exactly?

I'm constructing a circuit that needs both voltage supplies (for 3.3V RFID and 5V relay, GPS and screen) but the Uno is physically too big so I need to use a nano or mini pro, both of which I can only ...
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1answer
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Control a 5 volt water pump with an Arduino

I want to control (only on/off) a small water pump (5 V, 200 mA max.) with my Arduino. I read something about NPN transistor, because the output pins of the Arduino can't supply enough ...
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Grove temperature sensor with Arduino Yun

I try to test Grove - Infrared Temperature Sensor on Arduino Yun with the sample code but it does not work. In the console it shows that the object temperature is out of range all the time. However, ...
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Nothng Written to Serial when using sprintf

I'm using sprintf to use a format specifier myTemplate with some strings. The result will then be written to Serial. Although the sketch compiles fine, it does not write any thing to the serial, ...
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Slower nRF24L01 round trip delay than expected

Short/summary I expected that the round trip delay of a nRF24L01+ would be less than 1 ms. In practice I see around 3 to 5 ms and other sources have similar values. Does anybody know why this round ...
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1answer
477 views

Slave SPI does not work

I am trying to use both an SRAM (23LC1024) and SD card reader on an SPI bus. My connections (for SPI): Arduino pin 11 (MOSI) -> SRAM pin 5 (SI/SIO0) Arduino pin 12 (MISO) -> SRAM pin 2 (SO/SIO1) ...
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Modbus Protocol Compile Error

I have Code for Mod bus Library as below. I have Gone through lots of forum. How to assign device ID, slave address, length using below library function: #include <SimpleModbusSlave.h> #define ...
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1answer
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How can I programming detect that a Bulb/LED is ON/OFF or a circuit is working as expected using Arduino?

I've created a circuit to turn on bulb using GSM module and Arduino. I want a mechanism(or programming) to know whether the bulb is on or off or fused. I've tried taking the input from the pins. But ...
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Arduino Detect my move [closed]

I'm new to Arduino, but I have this idea for a Smart Bag I would like to build. I need the Arduino to be able to detect my moving by mobile and follow me. What would be the best way to achieve that?
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Bit mask first 2 bits of 16 bits for accelerometer

The datasheet for the accelerometer states that: Here is the data output from the accelerometer: I have tried to mask the first two bits using a bitwise AND command with B0011111111111111. I tried ...
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Problem with MP3 Shield and function calling combination

I wrote this code to control my Christmas tree. It plays the Holy Night Code perfectly but never transitions to the next song. In addition, it plays random notes after the song is finished. Does ...
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2answers
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avrdude: ser_open(): can't open device “\\.\COM4”: Access denied [duplicate]

I installed the new IDE Environment 1.6.6 and I got this error when compiling a program. I am using an Arduino Uno avrdude: ser_open(): can't open device "\\.\COM4": access denied I need your help.
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Arduino resets my MacBook Pro

Every time I connect the Arduino Uno to the Mac through USB port, the Mac restarts. Why is this happening? How can Arduino make such a sophisticated machine reset? This also happens with my ESP12E ...
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Arduino not responding while trying to flash over BLE

I'm working on wireless uploader for Arduino from iOS devices. I'm using HM-10 BLE module which seems to work ok. PIO 2 is used as DTR for resetting (see A [0x41] T [0x54] + [0x2B] P [0x50] I [0x49] O ...
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2answers
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Arduino LED flashes with one button press

I want the LED to flash when I press the switch once, but it keeps flashing. I tried the idea of just lighting the LED and keeping it lit with just one button press, so I wrote: int led=13,button=12; ...
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1answer
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How to connect a Pressure Sensor-MPX10DP to an Arduino?

I'm very new to Arduino, I'm trying to connect an air pressure Sensor without success. I followed this tutorial: Arduino Air Pressure Measurement The values I'm getting are very weird and the ...
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1answer
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Arduino LCD is displaying gibberish, sometimes

Below is my code and a picture of the gibberish. It's different every time. If i pull out the temp sensor, i still get gibberish, sometimes. I'm at a loss as to what to even be looking at now. Any ...
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2answers
381 views

How come my transistor doesn't work?

I have a TIP 120 to 229 NON 60V 5A transistor I'm trying to use it to switch an electro magnet. Using the blink example to test it out: // the setup function runs once when you press reset or power ...
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4answers
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2.8" TFT Touchscreen Prohibits Access to Unused Pins

This is probably a beginner question. You've been warned. I recently purchased a touchscreen (http://www.adafruit.com/products/1651#tutorials) specifically because it left so many pins open to work ...
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1answer
424 views

How can I give power to Arduino Uno using a 12V 7.5 Ah Lead-Acid battery?

I am trying to give power to my Arduino Board using a 12V 7.3 Ah Lead-Acid Battery but I am unable to do it. I connected the battery to Arduino Uno (via DC Pin) and it worked for a couple of minutes ...
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2answers
6k views

Setup arduino uno with ESP8266 ESP-1

Iam trying to set up the arduino uno with the wifi module ESP8266. I use this schematic setup: I have followed this tutorial: Tutorial ESP8266 Thereby I removed the Mega328P Chip like it says above, ...
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PID not working correctly

I'm currently working on a project where I need to use PID to get the correct speed for a motor when it is angled a certain amount. The problem is that I'm only getting 0.00 and 255.00 as the speed. ...
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1answer
57 views

How to get started? [closed]

I'm a guy who loves the tech world, but more in particular the Robotic one. I wanna start developing/making my first creations of robots or sort of. I won a little board from Texas Instrument from the ...
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GSM and GPS module don't work together

I am trying to create a project which involves getting latitude and longitude via GPS Module and send it via GSM Module. My problem here is that individual code is working perfectly. However, if am to ...
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2answers
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Sense checking Arduino Uno barebones schematic

I have had some difficulties finding a barebones Arduino board and have had the following made. I just wanted to see if anyone could spot any issues? I think it has everything. I'm really trying to ...
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2answers
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Generating PWM using Arduino Uno and Simulink (interfacing) pins 5 and 6. What's the maximum frequency?

I am building a boost converter using a mosfet. The mosfet is driven by PWM generated by an Arduino Uno through Matlab Simulink. In Simulink I am giving 10 KHz pulse width 50%. Practically 10 KHz ...
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3answers
486 views

arduino boot loader problem

I am using atmega 328pu instead of atmega328p-pu. I am trying to upload the bootloader using AVR pocket programmer. I have changed signature from 0x1e 0×95 0x0F to 0x1e 0×95 0×14. (Relevant link) ...
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1answer
792 views

Sending a character 'A' through blinking led

How do i code to send a character 'A' to the arduino through a blinking led? i am doing a project about data transmission. i really need help&some guide. Material used are arduino uno r3,...
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11k views

Controlling an LED using a transistor (TL188)

I wanted to control an LED using a transistor (my first attempt at using a transistor). I connected a transistor (TL188) to pin 13 of an Arduino Uno accidentally and noticed something. (The resistor ...
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2answers
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This error is shown continuosly after first time it compiles successfully

I got this error: Arduino: 1.8.5 (Windows Store 1.8.10.0) (Windows 10), Board: "Arduino/Genuino Uno" Multiple libraries were found for "LiquidCrystal.h" Used: C:\Program Files\WindowsApps\...
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6answers
3k views

Detect a non-human moving object

I would like to design a system in which I am able to make a light flash when a motion sensor detects a movement of a non human object such as a car. (The goal here being that when a car is moving ...
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4answers
493 views

Switching external power supply to 5V cooling fan with an Arduino and 2N2222 transistor

I'm using a 2N2222 transistor as a low-side switch to turn a 5V computer fan on and off with an Arduino digital pin, which responds programmatically to a button press - i.e. the relevant digital pin ...
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1answer
395 views

Modifying Arduino IMU library to rely on DSSCircuit's I2C Master Library

For an Arduino project I am working on, I am trying to modify the SparkFun 6 Degrees of Freedom IMU Digital Combo Board - ITG3200/ADXL345 to support DSSCircuit's I2C Master Library (https://github.com/...
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1answer
876 views

How to start particular event for particular time using millis()?

In my recent project, I want to run particular event for the particular time. For example, If I want to Turn ON my LED for 20 Second. And rest time LED must be off. I know using delay() it is possible ...
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2answers
321 views

How to indicate an End of a stream on USB

I am making a Lora-USB passthrough device using arduino and somehow I want to indicate that a stream over some data has ended. So far I have done: void onLoRaReceive(int packetSize) { if (...
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1answer
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How to read response from server using an Ethernet shield?

I want to control a relay by reading values from MySQL. I'm using an Arduino and an Ethernet shield. So far, I can get the response from server and get the value. I just need the value 10110110, but I ...
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2answers
8k views

Where is documentation on Arduino's Internal Interrupts?

First time arduino programmer here...however I have programmed the TI MSP430 in the past... I am trying to figure out how to configure internal Interrupt Vectors on this Arduino Uno. In the Arduino ...
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how to change variable when a button connected to pin 2 is pressed

Hi i am writing a code where, i have to switch a variable called toggle from 0 to 1 to 0.... every time the button is pressed (the button is on a 2 pin). I am a little lost as I am new to arduino need ...
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Switching methods/functions with a button

I am trying to program a basic counter using 7segment display and a button. What I am trying to achieve is the following: Display 0 at the beginning. When the button is pressed: Start Loop 0-9 ...
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75 views

when i finished coding my 3 dc motors, all these errors accrued one said stray '/302' in the program [closed]

/* #include <SmartInventor.h> */ void setup() { SmartInventor.DCMotor(); } void loop() { // M1, M2, M3 // CW, CCW, STOP // 0-100 // 0-360 SmartInventor.DCMotor(M1, CW, 10, 45°);...
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Read a String from serial to debug the AT commands sent to my GPS shield

I want to extract an AT command's response (via serial port) to find out if the GPS shield is working as it should be. I used: if(Serial.available()>1){ String response = Serial.read(); ...
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Arduino emits signal A (infrared) but another Arduino receives everything but A (IR-LED problem)

Situation: I was trying to make a simple Arduino program that mimics my TV-Remote ON-OFF button. Diagnosis: It just won't work. So just to check I grabbed another Arduino (2) and added my IR-Sensor ...
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3answers
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Storing array in PROGMEM

I have an array of a lot of numbers (1 and 0) but i can't store them since arduino does not have enough space. How can i save an array of example 00110 in PROGMEM, then read from PROGMEM and set x to ...
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1answer
56 views

What's wrong with my codes/

My teacher gave us a performance output about doing a dancing christmas lights in tinkercad. But I don't know what to do about the codes. He left an instruction to us about what to do. I follow it ...
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2answers
146 views

How to find the deferenced value of a transmit Port Register?

So I am working with the SoftwareSerial library. I'm looking at the write function and I see a *reg value being manipulate. I want to find the value of *reg so I traced the value by stepping into each ...
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1answer
32 views

Arduino ESP8266 Wifi Shield GET request with LiteESP8266Client stops after few HTTP request

Below HTTP Get request is working but after few GET request(5-6) the code stops and once I press Arduino reset button then only it start working. Probably looks like something is causing OOM: // This ...
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3answers
2k views

How I can print several numbers via Serial with very few lines of code?

Could someone help me how to output the numbers from 1 to 10 via Serial, without having to write out each command by hand? Below is my sketch - I need it concise instead of a long sketch: #include &...
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Sensors go crazy on external power

For few days, I am trying to figure out, why my sensors do not work on external power. I bought NodeMCU along with couple different sensors etc. I was happily working with them, connecting them one by ...

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