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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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33 views

MOSI pin not turning low

I have the following code: void initChips(){ SPI.begin(); SPI.beginTransaction(SPISettings(20000000, MSBFIRST, SPI_MODE0)); pinMode(SS, OUTPUT); digitalWrite(SS, LOW); } void ...
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2answers
42 views

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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1answer
29 views

HanRun HR911105A 17/20 Mini ethernet shield pins Dont 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
54 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
20 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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0answers
14 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
39 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
55 views

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
35 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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0answers
27 views

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
55 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
86 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
48 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
68 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
26 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
126 views

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
47 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
188 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
125 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
80 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
46 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
67 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
55 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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0answers
65 views

Keypad prints just 1 [closed]

I used this example code: #include <Keypad.h> const byte ROWS = 4; //four rows const byte COLS = 4; //four columns char keys[ROWS][COLS] = { {'1','2','3','A'}, {'4','5','6','B'}, {'7','8'...
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1answer
67 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
68 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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votes
1answer
122 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
1k 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
60 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 ...
0
votes
1answer
47 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
668 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
220 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
83 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
32 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
206 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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3answers
3k views

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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0answers
149 views

Is it possible to attach more than two Servos to an Adafruit V2 Motor Shield?

The Adafruit Motor Shield V2 allows two servos to be attached to 3-pronged headers. While the screw-in block terminals enable the use of 4 DC Hobby Motors or 2 Steppers, which are powered by an ...
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1answer
633 views

hx711 and load cell read out 0 for calibration

I'm using this tutorial from Sparkfun https://learn.sparkfun.com/tutorials/load-cell-amplifier-hx711-breakout-hookup-guide And using THEIR code. The only difference is I added a delay so it wouldn't ...
0
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2answers
35 views

Schematic interpretation, where to put resister?

I'm new to schematics, trying to figure out where to put a resistor (no instructions other than the schematic) I'm told I need: 10K variable Resistor x 1, 4.7K Resistor x 1, 100 Resistor x 1 But I ...
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0answers
226 views

ATmega328p PD0 and PD1 usage

I would like to use pins RXD and TXD (PD0 and PD1 in ATmega328p) as inputs. I am using Arduino Uno to upload a code to my ATmega328p, after that I plug in ATmega to my circuit board. Arduino Uno is ...
0
votes
1answer
43 views

What is the best way to configure a bidirectional, open collector data pin? [closed]

I want to communicate with an old keyboard asynchronously through a single open collector, bidirectional data pin. As part of the protocol, the timing will be controlled entirely by pulse width. I've ...
0
votes
1answer
231 views

Arduino Nano off 9V : is there any change to output?

I'm building a test circuit on an Arduino Nano that consists of a simple 220 Ohm resistor and an LED on pin D2 which is routed back to GND (ground). It's as simple as this: It's running a very ...
0
votes
0answers
27 views

Differentiating signals from piezos connected in parallel

I'm doing a project with multiple piezo sensors and due to conservation of pins and for the tidyness of the wires, I want to use as little pins as possible. For these reasons I'm thinking of ...
0
votes
1answer
124 views

FTDI and atmega328p-au [closed]

I want to connect an Arduino Pro Mini with ATmega328P so as to drive a SI4463. But I don't know BLK, CTS, DTR should be connected to what pins of ATmega328P. How do I connect this?
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1answer
112 views

How to drive 16 stepper motors with Arduino?

I'm trying to drive 16 of these little steppers on an Arduino Uno. Each test driver uses 4 digital pins for control (2 for each coil) so that would be 64 pins I will need. I'm thinking either ...
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1answer
217 views

Using TTGO TS 1.0 TFT display

I'm trying to use the TTGO TS 1.0 display with a demo app from a different source. The demo app wants the following to be configured: #define PIN_NUM_MISO 17 // SPI MISO #define PIN_NUM_MOSI 23 ...
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2answers
244 views

Share I2C pins with other device when lacking GPIOs

We're Using ESP12E as our MCU and we have three functionality : SIM800 connected to TX(GPIO1), RX(GPIO3) Matrix Keypad connected to GPIOs: 14,13,2,10,0,4,5,16 GLCD connected to GPIOs: 15,12 And we ...
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1answer
802 views

3 digit 7 segment display

I have 3 digit 7 segment display with 10 pins I found this image pinout but it not working for me I need to know the pin out of this display
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1answer
169 views

Need lot GPIO pins on arduino mega - what are restrictions?

I would like to use as much as possible GPIO pins on Arduino Mega especially with (mis)using pinMode(x,INPUT); and pinMode(x,INPUT_PULLUP); to achieve two things at the same time - drive something ...
6
votes
3answers
24k views

NodeMCU - Vin pin as 5V output?

I know that Vin can be used to power the board but have also been reading that it can be used as a 5V output. Is it possible to assign Vin as an output as I would any other GPIO? If I want to power ...