Arduino

Questions tagged [digital]

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Digital refers to signals which are either on or off (high or low, one or zero). This contrasts with analog signals which have a range of values.

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Help combining digital and analog code in arduino programming

So I'm making a device that does 3 things, Measures frequency of an audio signal through a microphone Checks whether there is a weight placed on a pressure pad (my pressure sensor works through the ...
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1answer
70 views

Red LED not turning off on Adafruit Circuit Playground Classic

When using the traditional Blink example program, the light blinks as expected. Even when writing from scratch digitalWriteing pin 13 to high and low repeatedly works fine. The problem is when I try ...
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39 views

`LOW` being defined as `0` and `HIGH` being defined as `1` - is this a part of external specification?

Arduino.h defines LOW as 0x0 and HIGH as 0x1. Does the Arduino API intend to expose that fact? Does it guarantee that this will always be that way? In other words, what is the intended purpose of ...
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24 views

How can I scan for a HIGH signal on digitalRead during the main loop, while running other things?

I'm working on a program which listens for certain bytes on serial through an if/then/elseif ladder. I want to also check if a pin (say, A15) has been given a HIGH state, by another Arduino with ...
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0answers
53 views

Cannot write pin LOW

All the other examples I've seen have had coding errors where they set a pin LOW in a loop with no delay so that it goes high again right away - but this problem is different, and probably something ...
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219 views

Using a water sensor with a NodeMCU make it less sensitive?

I'm trying to digitalRead from a water sensor (the one in the picture) using NodeMCU v3,when I try the sensor with an Arduino board it works fine, but when I try it with an ESP8266 NodeMCU v3 it ...
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1answer
44 views

Can I read using an analog pin on an arduino Mega whether or not there is a high (5v) voltage on a wire from another board's digital pin?

I am making a peer-to-peer network of initiating devices and a common hub, which controls most of the hardware. It sends a number over Serial to Mega's Serial1 (Mega's Serial is used for communicating ...
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1answer
154 views

Digital I/O threshold voltages for ATmega32u4

What are the voltages on a ATmega32u4 (eg Arduino Leonardo) such that a HIGH or LOW is read? I want to ensure that I'm reading the chip reference manual correctly, where Table 29-1 says: VIL: Input ...
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1answer
53 views

Is my code triggering the N-Channel MOSFET as I have intended to

I have a certain bit of code that I believe after 10 seconds will send a high signal to the second digital pin for 50 seconds. After it will not do anything. For some reason the nichrome wire is not ...
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2answers
195 views

Analog vs Digital Accelerometers - pro's and con's? [closed]

For my project i need to measure accelerations up to 16g. My options are either digital accelerometers such as the MPU6050 or MPU9250 or an analog accelerometer such as the ADXL326. What are any ...
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1answer
56 views

How can we use two devices at the same time with arduino?

I am using fingerprint module r307 and LCD together. In that, I am using 2,3 digital pins of arduino for data transfer to the fingerprint.(I tried other pin configurations for this but it didn't work) ...
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1answer
34 views

Elapsedtime variable not resetting

I am new to Arduino programming. Let me describe the application I am working on. I am pressing a button for a certain period of time (30 sec). I can not hold it in a pressed position for all the time....
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1answer
49 views

Routing Matrix with a large number of I/O [closed]

Lets say that i would like to make a 128x128 routing matrix with an arduino uno, Since i am unexperienced i think of using two 4051’s for 8x8 patching and because i want to persist the patch, ...
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1answer
135 views

Arduino UNO LED half brightness when connected to digital GND but not analog [closed]

I am using an Arduino UNO. When lighting an LED with the switch button on a joystick module, I have two situations: If the LED's cathode is connected to GND on the digital pin side of the Uno, the ...
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2answers
871 views

Sending a digital signal from one Arduino to another to trigger an event

I am wanting to send a digital signal from one Arduino to another. The goal is for one Arduino send a HIGH signal to a pin on the receiving Arduino. While the pin is HIGH, do function I initially ...
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1answer
1k views

Read frequency of input in digital pins

This is a somewhat theoretical question: Let's say I have some sensor that sends digital signals to one of Arduino's digital ports. Now, I don't know the frequency it sends those signals in. For ...
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3answers
59 views

For Arduino, is there a meaningful difference between carriage returns?

Serial.write(0x0d); // hex Serial.write(13); // ASCII Serial.write('\r'); // char Is one more efficient? I read how it depends on the terminal program. So does that mean the IDE? (This is my ...
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2answers
277 views

Digital Sound sensor

I am having trouble with my digital sound sensor. My goal: Clap 2 times and a led goes on. So I wrote this code. I don't know if it is correct or not. This happens: If I clap, from the serial monitor ...
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1answer
48 views

Error in finding frequency of an input signal

Here is my code to find the frequency of an input rectangular wave at pin 8 of the Arduino Uno board. const uint16_t freqPin = PB0; const uint16_t load = 0; unsigned long int count=0; unsigned int ...
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1answer
37 views

Digital selection for gain control not working instead showing 0

I am making a device which will have a button to measure the input and another button to reset and the inputs are variable analog values(0 to 5v) and output is a ratio of two analog input voltages. It ...
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1answer
131 views

How to digital read and send the data through serial to PC with speed around 2 MHz?

I would like to read analog data with frequency sampling around 2 MHz and send it to PC to be processed with python for digital oscilloscope. I use Arduino Nano. I have found ADC (AD9057, PDF) that ...
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2answers
495 views

Digital Band pass filter arduino 1100-1300 Hz

For a project I need to design an digital band pass filter. I started of with this in Matlab: wch=1100*2*pi; wcl=1300*2*pi; sys=tf([1/wch 0],[1/(wch*wcl) 1/wch+1/wcl 1]) sysd=c2d(sys,9615,'tustin') ...
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2answers
51 views

Upcoming Project [duplicate]

Hey guys I have a project that will require 20 I/O pins with serial communication from a computer to control each of the pins. I would like something as small as possible would a arduino micro or uno ...
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1answer
320 views

4x4 matrix keypad - Multiple inputs cause extra readings

I have the following matrix keypad - I am using this as a sort of controller with my Arduino (Mega2560) but I can't get real multiple inputs to work. I am able to have say two individual keys ...
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2answers
72 views

Where can I find the complete list of Arduino Serial Command & Query Strings?

I am planning to use the Arduino as a replacement for a USB-Controlled Digital I/O device, which will be integrated into an existing C++ software package that I created. I understand that the Arduino ...
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3answers
904 views

Fool Proofing My Arduino IC Checker [closed]

I am creating an IC checker for some high school juniors since a faulty IC can be a nuisance of a bug to find when bread-boarding. These ICs are all simple TTL gating from the 74LS series; the set I ...
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1answer
49 views

Light Powered Motor Troubles [closed]

I'm working on a small car (<1 kg) which will drive when there is light and stop when there isn't. Below is a plan with code drawn up (the only numbers I know for sure are the current gains for the ...
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1answer
95 views

Consequences of dynamically changing input/output configurations of digital pin?

I am creating an IC checker for a large chunk of the 74ls series (basic TTL logic chips), which means that I have 14 pins running to the IC to verify its functionality. One pin is power (+5V) and ...
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3answers
519 views

digitalRead keeps giving 1

I am new to arduino programming and I have bought arduino UNO a few days ago. I am trying to read the value of pin 4 using digitalRead with pinMode INPUT_PULLUP but it keeps giving me 1 even when the ...
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1answer
280 views

Connecting two analog multiplexers (CD4051b)

Is it possible to connect two CD4051b analog multiplexers together so that I can receive 14 analog inputs through them? Just by using one analog pin and three digital pins on the Arduino UNO.
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1answer
72 views

Need to “Extend” a Arduino Digital Signal

Here's the scenario: We have 1 arduino uno accepting DMX and converting that to a signal that is being sent out digitally (PIN 3). The digital signal then goes to several IR LED senders that control 3,...
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2answers
31 views

Powering via an I/O Line

I have an SPI 128x64 OLED display. Is it safe to power this display's VCC from a digital I/O pin? I would like to do this so I can connect it flush to my arduino's header, and so I can control the ...
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1answer
208 views

Why would digital outputs on Arduino Due be less than 3.3V?

We are working on a project that requires a temperature sensor to tell the Arduino Due to turn a digital pin to HIGH (3.3V) to active a relay so a heating pad can be powered on. We have diagnosed all ...
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1answer
587 views

Controlling an MCP41HV31 Digital Potentiometer

I need to control a 10kOhm digital potentiometer in rheostat mode in 256 steps. I found an Arduino tutorial, which works with an MCP41010 (I added a viper resistance according to the datasheet). This ...
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2answers
202 views

Arduino-based mains frequency monitor follow-up

Following my previous question, I'm getting closer to thinking about putting together this mains frequency monitor. I would just like to do a sanity check on my electronics before I order the ...
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5answers
507 views

Arduino-based mains frequency monitor

I'm looking to put together a simple mains frequency monitor based on the Arduino platform. The mains here are 250 V @ 50 Hz, but obviously these fluctuate slightly, which is the whole point of the ...
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2answers
309 views

Why digital pin not reading ON from push button switches connected to 5V and pull-down 10K resistor?

Here's my circuit: And the code: //pins const int control1 = 2; const int control2 = 3; const int enable = 9; const int pinDirection = 4; const int pinOnOff = 5; const int pot = A0; //states ...
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1answer
391 views

Too low voltage on digital input on attiny45

I'm using one of my attiny's pins as digital input. I use it with a pulldown resistor. As input I use simple square wave generated by a separate waveform generator. igh state for square wave is 5V, ...
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1answer
592 views

Arduino Control TV over RS232

I have a LG TV(LG 32SL800 ZB), which has a RS232-Port for Control and Service. And I am wondering if I could control this port with my Arduino (NODE-MCU) and a module like this one RS232 Board? How ...
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7answers
28k views

What's the difference between analogWrite and digitalWrite?

As the title states. What's the difference between the two? analogWrite(pin,0-255) vs digitalWrite(pin,LOW-HIGH)
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1answer
801 views

3 buttons digital inputs [closed]

I have 3 digital button inputs, I want to do a continuous scan of 3 of them until a button is pressed and to know which button has been pressed. Please help, I'm new to programming and arduino. ...
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2answers
1k views

The fastest way to read out a digital pin state in an Arduino Due

What is the fastest way to read a digital pin status in an Arduino Due? Is it possible to achieve speed in the Nanosecond area? With which type of code I can achieve this? Edit: This question is not ...
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2answers
104 views

Trying to explain strange behavior when attempting to do a digitalWrite to A7 on a pro mini?

I found out the hard way today that pins A6 and A7 can't be used as digital outputs, but what actually happens when you try to read/write them? Some backstory: I soldered some headers onto a pro mini ...
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3answers
5k views

How do you configure ADC7 on the Arduino Pro Mini as a digital output?

I'm attempting to use the pin labeled 'ADC7' from the Atmega328p TQFP package. The Atmega documentation suggests that can be used either as an analog or digital I/O point. I'm trying to configure it ...
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2answers
234 views

manual square wave period is off

I'm generating a square wave with my Arduino UNO using the following: #define pin 10 // data pin to control servo // pulse width (in microseconds) int pulsewidth = 2500; // 400 Hz // wave period in ...
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1answer
44 views

Measure voltage of data output?

I'm trying to control a few NeoPixels using a 3.3V Particle Photon. I've got a 5V power source that I'm using to power the NeoPixels (as they require that voltage. That works fine. Them I'm using a ...
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1answer
333 views

What is the datatype of the pinMode function?

I just tried it, but the Arduino IDE crashed, I hope its not related. I want to declare a datatype like this: int a = pinMode(pin, OUTPUT); or something like that, but I'm not sure what datatype the ...
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1answer
1k views

Sending digital signal from one arduino to another

I have one arduino with two proximity sensors that send two digitalWrite signals if an object is detected. I checked to make sure the output of these is working properly and only sending high signals ...
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1answer
82 views

Interfacing Digital clock with Uno

I want to take input from a clock for a specific time and respond to it. I am taking alarm as input because it will send some signal to a buzzer and I want to decode it through Arduino. I am using ...
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1answer
321 views

Perform function after a period of time

I am working on a project that I am supplying with voltage an LED through a digital pin (26) and I want the LED to be switched off after 4 seconds. I am using Arduino Mega2560 and I am programming it ...

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