Questions tagged [pins]

"Pins" are like gateways between the Arduino code running on the chip and the components attached to Arduino. It can refer either to the physical connectors on the board, or it can refer to the pins defined in the code.

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524 views

Output 3.3V when setting pin to high

I would like to pass 3.3V and Ground to an component. How can I achieve such a thing? I for example would like to let a wire get 3.3V when I for example do digitalWrite(pin, HIGH). It is hard for me ...
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205 views

How to set cables to connect Cp2102 to Pro Mini?

How to connect the cables in order to program the pro mini with the CP2102 usb interface ? The TX RX and GND is easy, but I am not sure about the RST, DTR, DST, etc I attached the images of both. ...
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2answers
219 views

measure +3V and -3V through resistor divider and switch on/off by digital pins

I've seen that resistor dividers can be used to read negative voltages, but I'ld like if there is a way to accomplish this with less components and having a way to turn this off. I was thinking if ...
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1answer
45 views

Which sources of randomness are available? [duplicate]

I need a souce of randomness to generate a seed to pass to randomSeed. Where can I get this randomness from? Well, I hear I can read random noise from an unconnected pin. But I need to connect 9 ...
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2k views

Can I use the PWM pins as regular digital input/output pins?

In regards to the arduino which has pwm pins, can I use these pins as normal input/output digital pins or not? Thanks in advance.
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HC-05 Bluetooth module on breakout board with straight header pins

Has anyone found the HC-05 bluetooth module (on the breakout board) with straight header pins? I seem to only be able to find them with the 90 degree header pins. Removing those and soldering on ...
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3answers
1k views

Is there an alternative to soldering to connect boards?

I know that shields are usually soldered to headers so they can be attached to the board with the Arduino. I have a tremor, which makes soldering impossible. Are there ways of connecting PCBs without ...
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1answer
73 views

Spi based pin expander for Arduino

I don't have enough pins on my Esp32 board. I would like to use a pin expander. All the ones I could find online only use i2c. Are there ones available that use SPI? I would like send pwm signals to ...
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37 views

What type of power supply is the Arduino Due’s 5v pin and what is its current?

I’m looking to use a Futaba Servo with my arduino Due and was told it requires a “high current 5 volt supply” and I don’t know much about current so excuse my arrogance. I know the arduino Due has a 5 ...
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2answers
57 views

Ways to add pins in an arduino

I'm making a project for school where I'm using flex sensors and converting that into words on an LCD (similar to the signing glove if you're familiar with that). I ran into a problem since the ...
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1answer
238 views

Nodemcu ESP12-E (ESP8266), Can I reprogramming when the UART pins are defined as GPIO?

I wonder if there may be any problems using the pins that the UART are using as GPIOs, if now I want to be able to reprogram the circuit? (Of course I will detach the ESP12-E from the mainboard before ...
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191 views

For Arduino Uno it is possible to use the digital pins with PWM to read analog data, is this also possible with the Wemos D1 Mini?

I want to read out data from a load cell, for this I seem to need 2 analog input pins, the Wemos doesn't have this. In the Arduino I was also able to use the digital pint with PWM, there are also ...
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How to stop and repeat a melody using a button?

How can we make our melody stop when we press the button the first time and repeat the melody when we press the button the second time? // Noterna defineras #define NOTE_B0 31 #define NOTE_C1 33 #...
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167 views

What is the maximum number of sensors that can be operated on a single Aurdino unit

I currently have an Aurdiuno uno and a motor driver shield: (http://www.hobbytronics.co.uk/arduino-motor-shield). Now, I would like to run the following mechatronic devices: 3 bi-direction motors, 1 ...
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2answers
57 views

How can I discard power from a device I want to read from?

I want to read the data line from a device that normally interfaces with a controller. It has 3 pins, 3.3v power, gnd, and data. I don't need the power line since the Arduino will be USB powered and I ...
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133 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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What data type are the analog pin labels (A0, A1, etc)?

Arduino Mega I would like to have an array containing analog pin labels something like... int analog_pins[] = {A0, A1, A2, A3}; int num_analog_pins = sizeof(analog_pins) / sizeof(analog_pins[0]); ...
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338 views

Mini ethernet shield pins don't have SI

Please somebody who had the same issue help me. The question is how to connect this Mini Ethernet shield to an Arduino. The main problem is the pins that my shield have or haven't; my current ...
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1answer
463 views

Cannot set MOSI pin low even after ending SPI

I'm building a battery operated device and must shutoff MOSI pin during sleep because it leaks current through the SD card if I don't (about 400 µA). Problem is, it won't stay off. I've looked at ...
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1answer
126 views

Question on pin management using PCA9534PW IO Extender

There is an IO expander PCA9534PW, Arduino UNO. I don’t really understand how I can manage this expander using UNO over I2C. I found an example, but here is the reading mode. What I need: Set the ...
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57 views

digitalWrite on Trace SWO pin

I'm using STM32(generic board) and I want to control bi-color LED(common anode). STM32 pin layout and scheme is below, so please see it. Now, in theory scheme Works, but in practice it Works halfway. ...
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1answer
395 views

arduino is skipping the if statement [duplicate]

Hi guys I am new to this language and i just tested the code to control a servo motor Can anybody help me please ? here is the code void setup() { servo_test.attach(3); pinMode(9, INPUT); ...
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2answers
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How do I provide a negative current?

I'm trying to use an ATMega328 board to control a board of a broken UPS device. I replaced all the internals of the UPS by custom components, so the only things which remain are the chassis and the ...
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0answers
196 views

Bit Bang I2C with port manipulation on AtTiny84: new pinout doesn't work

So I am trying to understand bit banging and port operations. I'm developing a breakout board with an ADXL343 IMU read by an AtTiny44 via i2c. I adapted this code from MIT's How To Make Almost ...
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ESP12e pin 13 won't set to output/won't work

I have an ESP12e and running a basic blink code on it. The problem is that GPIO13 of esp12e wont turn on. I have noticed that this has happened from time to time. Earlier I thought that the ESP was ...
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2answers
805 views

ATmega 32A and 2560 R3 register to pin mapping?

I've been doing research for the last few hours trying to determine the mapping of physical pins to memory-mapped I/O registers for the Arduino Mega board (which is an ATmega 2560 R3). My code is on ...
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2answers
180 views

What is the state of Arduino pins when the arduino is unpowered?

I'm building a control box to provide logical control of power outlets. I'm using a 4 channel 5V optically isolated relay system to control 4 separate outlets. To use optical isolation you connect ...
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2answers
253 views

Can you current-limit Arduino 101 GPIO pins?

A number of questions ask about max possible in/out current on a GPIO pin, that's not my question here. I'm asking if it's possible to set a maximum current limit on a GPIO pin, such that any attempts ...
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1answer
765 views

Detect power interruption on NodeMCU

Im using a 5v 1A power supply and connected to VIN pin on the NodeMCU. I also use 18650 battery to keep NodeMCU running in case the power supply shuts off due to power interruption. I'm planning to ...
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1answer
167 views

toggling Rx, Tx pins after Serial.begin

What should one expect when the following program runs on Arduino Uno? void setup() { Serial.begin(9600); DDRD |= 0b11; } void loop() { PORTD |= 0b11; delay(100); Serial.print("...
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1answer
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esp32 spi library, how read a mcp23s08 register

thanks for any help I need to read a gpio expander mcp23s08 set as 8 bits input. my code write correctly (I believe) the setup register using SPI library, with the enclosed example modified. But I do ...
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1answer
86 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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0answers
2k views

Stepper Motor button control with A4988 Driver

So I'm quite new to programming and have inevitably worked myself into a corner. What I am trying to accomplish is to allow for a stepper motor, (powered by an A4988 driver) to move with the push of a ...
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3answers
8k views

How can I get my (Arduino) Pro Micro schematic to allow me to program it through GPIO instead of USB

I'm trying this project so far I've got the schematic of a Pro Micro, which is powered through GPIO from a Raspberry Pi Zero, and want to remove the micro usb connection and able to flash it using an ...
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1answer
504 views

Connecting Winsen ZE11-C2H4 Sensor to Arduino

How should I connect the ZE11 Ethylene Sensor to an Arduino Uno? I want to know how to attach the pins of the sensor to the Arduino and which resistor I should use. I'm very unprofessional at working ...
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1answer
91 views

Attaching Microcontroller to DAC evaluation board

For an independent undergraduate research project I'm trying to construct a digital feedback loop. I have never used an Arduino, or done much electrical/computer engineering, so I'm just taking things ...
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1answer
836 views

The Capacitive Sensor library on a D1 Mini

I want to set up a hand-made capacitive sensor on a D1 Mini, as in this tutorial, so that I can get specific capacitive readings. But I couldn't get the CapacitiveSensor library to work with the D1 ...
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2answers
77 views

Weird behavior (Couldn't pull the pin LOW)

I was trying to implement my own code to control a stepper motor on arduino uno, however I noticed that the pins were always HIGH despite what was written to them. I started to erase the code to leave ...
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1answer
213 views

How to have multiple digital outputs for the same pin on Arduino Uno and Simulink?

I'm trying to develop a PID controller with Simulink as shown in the image PID. I'm using a PID controller to control a motor via an Arduino Uno and motor driver. I have the PID output connected to ...
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3answers
228 views

How to monitor state of 50 Digital Inputs

Good day. I have a specific project need and I spent the past couple of days searching on forum, blogs, etc and I'm still not clear if that's feasible to do with Arduino or not. I need to monitor ...
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1answer
415 views

MCP2515 CAN bus with Arduino

I'm using MCP2515 CAN controller and TJA1050 transceiver. I want to send some square waves to TJA1050 with digital write and delay instruction of Arduino. How can I do that? I also read the MCP2515's ...
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1answer
4k views

ESP 12 unusable pins

The ESP 12 board has 22 pins Are all of them usable? I understand that there is an external flash memory that is accessed through SPI, but I'm not sure what the impact on the pins is. And if it is ...
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1answer
66 views

The reason for signal not going back to LOW

I have written a simple Arduino sketch, that shall produce a clock signal. Here is the code: void setup() { // put your setup code here, to run once: } void loop() { // put your main code ...
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1answer
93 views

Switch two or more digital outputs of ESP8266 at the same time [closed]

I'd like to control some digital ICs with a ESP8266-12. How can I switch 2 pins to HIGH in the same moment? How can I switch one to LOW and the other to HIGH in the same moment? Is it possible with ...
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1answer
4k views

INPUT_PULLUP not work for D8 in my NodeMCU v3

I changed my arduino NodeMCU application pin mode to use INPUT_PULLUP mode instead of INPUT. D8 input pin is not working as expected, I is always in LOW even the button is pressed or not. I have 3 ...
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2answers
2k views

Checking a jumper between two pins on Arduino

I'm in the process of making a tag scanner (which transfers the tag ID to the computer), and I figured I'd use an Arduino Micro for that and just use the keyboard function on it to save myself a whole ...
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1answer
165 views

How do I connect my Luxorparts keypad to my Arduino?

I just bought a 12 digit keypad from Luxorparts and it doesn't come with any schematics showing how it's wired at all. How do I figure out how to connect it to my Arduino?
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2answers
174 views

Does a pin (input pin Arduino) still float when connected to GPIO on RPI?

I am currently testing my application on an Arduino, and I experience floating pin issues. My program reads the pin status of input pins, which are configured as pinMode(5, INPUT); digitalWrite(5, ...
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1answer
561 views

Uno pin connection: Atmega16u2 & ATmega328P

On my Uno, I set up the HoodLoader2 (link below) so I can program both the ATMega16u2 and the ATmega328P. I can communicate between the two using the serial port. However, I need the serial port to ...
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5answers
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NodeMCU - use flash button as input in loop()

I couldn't find a proper answer on the net so I came here as a last resort. So I want to use the FLASH button as an input in the loop() method. Is there a way the check if it's pressed or not?

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