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1500 questions
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2 answers

I2C sensors not working when I connect to LCD 20X04

I am making a hydroponic nutrient monitoring system using Arduino Uno, Atlas Scientific EC sensor, pH sensor, and RTD (temperature) sensor in I2C mode. I also want to use LCD 20x04 to display the sensor reading so that will display the EC, pH, and…
Angela Radityatama
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Ethernet library compilation error

I'm trying to connect my Arduino to the internet, but my Ethernet connection config code fails when I try to verify it, and I'm not sure why. I'm using an Ethernet shield and have installed the Ethernet library v.2.0.0. This is the running…
KostR
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Does Nano not get sufficient power via USB?

I have an Uno, and I can play all I want with it, just using a USB cable. Then I got two Nano clones, and they both show the same behavior: When I connect it to the USB cable (which leads to my PC) it blinks a few times, then seemingly does…
Mads Skjern
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ESP32 Wifi not working when powered by battery

I'm quite new to ESP32 development. I've been using this devkit for a few small projects and everything was going smoothly until I decided to run it on battery. In particular, the ESP32 devkit I'm using, when connected to a battery, seems to have…
luigi
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4
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2 answers

How to make an Arduino act reliably as an SPI slave?

I want two Arduino Nanos to communicate with each other using SPI, ideally at around 2MHz or faster. I have two standard Nanos running at 16MHz on 5V. The master uses SPI.transfer() to send an array across the wire.¹ For ease of troubleshooting,…
Infinity Computers
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1 answer

How to determine when a sensor's output signal changes significantly?

Starting with an analog signal from any sensor, how do I automatically determine if there is a real signal change or a reset? Below is the sample code that better explains my goal: value = sensorRead(); if (millis() > t + 1000) { value_old =…
boromyr
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Arduino Array Scope with SPI

when I try the following code the SPI works correctly (see oscilloscope plot) #include void setup() { SPI.begin(); } void loop() { SPI.beginTransaction(SPISettings(100000, MSBFIRST, SPI_MODE3)); byte a[] = {0xC,0xFF,0xFF,0xFF}; …
user1441016
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Controlling a 5V fan and ultrasonic fogger with an arduino - do I need an external power supply?

I know the whole controlling a fan with an arduino thing is getting old, but somehow I still don't get it to work. Tried to answer it based on other questions but I am too much of a newbie to extrapolate the info there to my specific problem. For my…
crabdance
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1 answer

How do I listen for a sound that matches a pre-recorded sound?

I'm working on a project that uses an Arduino Uno to listen for a bell ring and then uploads to a web server the exact time the bell was rung using a WiFi Shield. I want to know how I can listen for the bell ring (a three second long high pitch…
Ben
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4
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2 answers

Random access to SD card using SD.h or another library (ESP32)

I'm trying to use a SD card with my ESP32 in order to save some variables in a txt file. Each variable uses 1 byte, so they can be represented by an 8 bit extended ASCII character. The issue is it seems that the SD.h library has only 3 open modes…
AlexSp3
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1 answer

Acrylic enclosure for Arduino

I've been browsing Aliexpress and eBay for decent Arduino enclusures, but I've found out they are even pricier then boards themselves. Then I've realized that there are multiple firms that offer cheap laser cutting - I can buy 1 sq.m acrylic sheet…
Alexander
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Is there an Arduino simulator that runs on Mac OS X?

I need to simulate my Arduino project with other circuit components before implementing the project. Is there a decent simulator that runs on Mac platform?
M.Medhat
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4
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1 answer

Arduino ESP8266WebServer hangs after a while but responds pings

I have an ESP8266 module that I use to be able to power on three computers if they are off. The ESP8266WebServer has what I needed to have a POST method rather than a simpler GET one since I am sending a password and I want that little extra…
Elder
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4
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3 answers

Stable frequency generation

I'm trying to work out the best way to generate a stable frequency with my Uno R3 I'm using interrupts to generate an approximately 40KHz frequency which drives some ICs/MOSFETs to effectively generate 40KHz AC which powers a transducer. I need to…
Ramrod
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5 answers

Why use a module rather than sensor directly?

I'm trying to understand when one would use an Arduino module rather than directly a sensor. Here's an example to contextualize my question: I need to use a Hall sensor to measure the number of rotations per minute of a magnet mounted on a computer…
Andrea
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