Questions tagged [pull-up]
Refers to pull-up resistors, which are commonly used to "weakly" pull a signal line to a high state. Use this tag for discussing pull-ups.
57 questions
0 votes
1 answer
83 views
Sketch halts if button is pressed on boot
I have a KY-040 rotary encoder with a push button wired to an ESP8266. My objective is to be able to detect if the button is pressed or not on boot. In the below code, if I hold the button down and ...
-1 votes
2 answers
788 views
Arduino Pro Micro not recognizing INPUT or INPUT_PULLUP
I tried to make a controller box with multiple buttons. Sadly, when I tried to connect the buttons, the Arduino Pro Micro didn't recognize them being pressed. I even tried to connect a wire directly (...
- 15
2 votes
2 answers
537 views
Barebones AVR - Connecting RESET pin to Vcc
I want to build my first barebones AVR circuit. I plan on NOT having a RESET button. For this reason, is it valid if I connect the ATMEGA's RESET pin to Vcc directly? What I mean by this, is that in ...
- 1,435
1 vote
0 answers
42 views
Poor Contact and Low Current Issues with Microswitches in Arduino USB Game Controller
I have made a USB game controller using the Arduino Micro and Omron microswitches (VX-01-1A3) for the buttons. The switch is wired with one end connected to a digital pin and the other end connected ...
- 11
0 votes
0 answers
288 views
How to work with a pulled high input pin where it needs to read a value from an analog sensor?
I have a small ESP32 module, that has some in-built features, like a TFT, and has few available pins for general use. It has some input only pins (GPIO36 to 39) that are used by buttons soldered in ...
- 113
1 vote
1 answer
162 views
Will I need the internal pullup resistor if no button is used?
Given I have two Arduinos that are supposed to primitively communicate with each other using digital pins. On Arduino Ar1, pin D13 is to be used as an input, connected to Ar2's D2 pin. Will I need to ...
- 33
3 votes
1 answer
714 views
Input Oscillating Wildly
I'm trying to read an input from a switch but instead of getting 0 and 1 for closed/open, I'm getting 0 and a rapid series of 1s and 0s. Originally I tried (and failed) to simply read a rotary encoder ...
- 39
0 votes
1 answer
141 views
DS1337 with shared I2C pull-up
I have a project using an ATMEGA328P and a DS1337 RTC chip. The DS1337 is an 8 pin IC with VCC at pin 8 and GND at pin 4. According to the datasheet both pin 5 (SDA) and pin 6 (SCL) need an external ...
- 41
1 vote
1 answer
633 views
I2C pull up resistors and an I2C MUX
I have a rig with 5 light sensors on an I2C mux and I am wondering if I need only 1 pull-up resister set for the whole bus or one on each branch from the mux? Or should I remove all the pull-ups from ...
- 121
1 vote
1 answer
219 views
How to test custom cables?
I'm trying to make a cable checker to help me make custom cables for my computer. I'm thinking I plug the cable ends into sockets on the device, then the Arduino checks between different pins to make ...
- 11
3 votes
4 answers
2k views
Can internal and external pull up/pull down resisters be used together?
What happens if a sketch uses code like pinMode(18,INPUT_PULLDOWN) to configure internal pull-down (or pull-up) resistors, but is used in a circuit where external resistors are also present? Are there ...
- 200
1 vote
0 answers
82 views
Reading ground signal from circuit
I am trying to detect whether a signal is high or low from an ESU LokSound 5 decoder for HO locomotives. My idea was to use one of the auxiliary pins used to drive an LED (AUX 3 in my case). The ...
- 185
0 votes
1 answer
586 views
What is happening when digitalWrite(pinname, LOW) is invoked after pinMode(pinname, INPUT_PULLUP)?
I read the Arduino official docs on digitalWrite and am confused about what is happening from an electrical perspective when digitalWrite is invoked on INPUT_PULLUP pins. Say my code says this: ...
- 170
1 vote
1 answer
497 views
Current difference between pinMode(pin, INPUT_PULLUP) and digitalWrite(pin, HIGH)?
Does pin 5 or pin 6 use more power if they're just being used as a signal to an external device? pinMode(5, INPUT_PULLUP); pinMode(6, OUTPUT); digitalWrite(6, HIGH); . EDIT: Thanks to some links ...
- 170
0 votes
2 answers
177 views
Detect if a display is connected
I want to detect wether a display is connected or not. This is the display: https://www.az-delivery.de/en/products/1-77-zoll-spi-tft-display I read connecting a pin of the display with another pin ...
- 121