Questions tagged [gpio]

GPIO is an acronym for general purpose input/output. The term is typically applied to a pin on a microcontroller (or other device) that may be changed between an input and output under software control. It can be used for an application defined purpose, as opposed to being constrained to a single designated function.

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Microcontroller default state problem

I have a Microcontroller - S32K116 - 48 Pin IC. - Datasheet - Reference Manual I have a Voltage divider (for input voltage monitoring purpose) connected to the Pin 16 (PTC3) of the Microcontroller. ...
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Do the MCP23S17 GPIO pins need protection against latch up ESD within this circuit?

I wrote about this system before. I will focus my questions now on "ESD protection" direction. I have an SPI based system in which a Raspberry talks with a GPIO expender device using SPI ...
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ESP8266 with ultrasonic sensor, booting custom circuit and using gpio0, gpio2 pins for echo and trigger - would this set-up work?

I am designing a circuit from scratch with an esp12 module. For booting the esp8266, the GPIO0 and GPIO2 need to be pulled up to Vcc (3.3V) and GPIO15 needs to be pulled down to GND. I added to my ...
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Ways to ruggedize 40 pin header for Rugged environment

What are the options for operating a 40 pin header (usually for UART, SPI, CAN, I2C, I2C, DMIC, GPIOs) in a rugged environment? So that the connections stay put and wires can be handled easily.
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How can I make a half-duplex UART to TTL converter for communicating to a servo with a HC04 and a HC126?

I have been trying to configure this circuit for some amount of time. I am using a HC04 chip and a HC126 chip. The HC04 is an inverter chip. The HC126 is a buffer gate. I found that for the servo ...
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Why is the MCP23S17 device getting too much hot suddenly and randomly Raspb 4A?

Circuit is a Raspberry Pi 4A SPI master node talking with one MCP23S17 device: datasheet. I'm testing the singlest circuit version in a protoboard. We are using A bank GPIOs for reading, and B bank ...
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EL wire and Raspi- is it safe and possible?

sorry for all of these questions, but I just want to check before I break anything accidentally :P I want to connect EL wire to my raspberry pi and control it via GPIO, but was wondering about the ...
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Can we drive an led from output port of TCA6424ARGJR IC?

I am using TCA6424ARGJR IC so from its output port 24 I need to keep an led, which glow when there is high. Can we drive an led from output port of TCA6424ARGJR IC? I have connected as shown in IMG.
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191 views

How to protect GPIO from back current? Diode? [closed]

After frying a Rpi with this montage 6 months ago: I followed advice from kind users here and modified the wiring to this back in February: It has been working fine for 6 months and suddenly ...
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Help replacing a physical joystick for motor control with a LabView program

I'd like to start by acknowledging the similarity of this question to this one, but I really need a more basic, step-by-step explanation. I am trying to help a student in my lab design a program to ...
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Is there anything wrong with this simple circuit ? Transistor + LED

This is my first time posting a question. So this is a simple circuit that I have on a PCB. A 2 in 1 LEDs with a common anode. As soon as I power my PCB both LEDs turn on even if the base isn't pulled ...
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Which libs to use with a STM32F103C6 microcontroller? [closed]

I'm very new with ARM microcontrollers and I've been doing a lite lecture of about 4 books to know how to configure this devices to start programming them. First I did a reading an how to use mbed but ...
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On/Off latching circuit with a raspberry GPIO 3.3v

I'm currently failing solving my problem. Of course if I would good better in electronic, I would not post my question here but that's life, and any help would be appreciate. Context: I have around 50 ...
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Benchmarking C++ functions' execution speed with GPIO and oscilloscope

For a research project, I'm trying to determine the execution time of various C++ functions on a Raspberry Pi and an STM32 microcontroller. To do so, I plan on triggering GPIO pulses before and after ...
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ULN2803 behavior when its output is not connected to any load in this circuit?

I'm studying the a circuit that is using a driver ULN2803 datashet. The driver is needed for external loads as LEDs when a pin is writing. The situation that I would like to talk about is when the pin ...
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One LED capable of being turned on by two IC's

simulate this circuit – Schematic created using CircuitLab I want to be able to turn on a single LED with either one of these two micro-controllers. Would there be anything wrong with this ...
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Controlling 3V3 relay from 2V8 (VL53L1X) GPIO output with PNP transistor

I need high side switch for 3V relay (exactly RM40-3021-85-1003 with 45ohm coil -> need ~65mA). I have multiple VL53L1X (ST's ToF distance sensor, 2V8 logic levels) connected with theirs OC GPIO ...
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Clarifying some doubts regarding PUPDR register of the GPIO [STM32]

Might come off as a trivial question but when does one use Pull up and Pull down as PUPDR register of the GPIO? I'd guess it's used to define the default state of ...
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Raspberry Pi3 - Configure 4 DC motors

I need to feed 4 DC motors of 5V on my Raspberry Pi 3 Model B using PWM (Pulse Width Modulation). Currently, I have the next components: 2 NPM transistors, 1 L293D integrated circuit, diodes, ...
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Light sensor connected to GPIO input of raspberry pi

I have created simple light dector. Schemea is below: Real circuit on breadboard: I have written code in python using GPIO library: ...
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Connecting loads to an MCP23S17 GPIO outputs

I would like to connect various MCP23S17 datasheet devices to the Raspberry Pi3 MB SPI port. But first I would like to start making some test with a single connection: only one chip. After this I will ...
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What about MCP23S17 GPIO pins output ports being also used to be read by input pins?

We are connecting Raspberry Pi3B with some MCP23S17 expanders: MCP23S17. I have read that they could emulate an open-drain outputs, playing with high Z state of the pin when configured as input. ...
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Does a Mcp23s17 output pin keep the value after being unselected?

I'm designing a SPI based communiations circuit between Raspberry Pi4+B as a master and (n x 8) GPIO expander modules, as slaves. Concretely we have selected an MCP23S17 GPIO expander: Datasheet By ...
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3-Pole Circuit Breaker with GPIO

I'm starting a small project involving 3-pole circuit breakers and 3-ph motors. There's this custom built machine with multiple 3-ph motors, each connected to circuit breakers. The purpose of the ...
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56 views

Continuity test on potential-free contacts

When testing connections on working binary potential-free device Siemens N 262E01 I have accidently put continuity test between two contacts. I analyzed continuity test, and found its maximum values ...
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is this level shifter a dud or am i doing something silly?

i am very new to hardware circuitry and am attempting to connect a wiegand rfid and pin code reader to a raspberry pi for door access control logic. more details at: https://gist.github.com/grenade/...
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Applied 370degC at the input of an ADC in a Microcontroller

I am using this Microcontroller - 100 pin I have configured pin 82 as an ADC input. ADC Reference voltage is 5V (provided from an LDO whose input voltage is 12V) To test my ADC accuracy, I took a ...
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Setting GPIO pin sate before initialization

I was going through ST Microelectronics code and found the following code ...
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1answer
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Use one GPIO output to set two inputs to opposite states (low and high)

This is all still very new to me so apologies if this is a silly question. I have two LDO voltage regulators, each of the ENable pins are different, to enable them one ENable pin must be LOW and the ...
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nRF52 GPIO configuration in sleep mode to prevent peripherals from drawing current

I have a battery-powered board with an nRF52832 and some peripherals that I am writing a new firmware for. When set to sleep (NRF_POWER->SYSTEMOFF=1;) the board still draws way too much current (...
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Using digital pins for reading analog value

When I connect the pressure sensor to an analog pin of WEMOS D1 MINI board I'm getting values between 300 when the sensor is not pressed, and 700 when it is pressed....
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RC522 has other pins than shown in all the tutorials

I've bought an RFID RC522 module which I intend to use with my Raspberry Pi 3B+. I read the following tutorials and I noticed that their modules have other pins than the one I bought: https://www....
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GPIO Open Drain LED driving

I was trying to understand GPIO open drain configuration. As far as I understood, to avoid floating output, one should use internal or external pull-up resistors. This is OK. However, I saw multiple ...
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43 views

How to interface camera sensor to microcontroller

I want to make robotics vision project. Ideally one would want to go with hi tier expensive sensors, they have no such problem, because they are interfaced directly to x64 CPU, via PCIe bus. Thus, raw ...
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48 views

Power dissipation of a current limiting resistor (connected to an input pin of uC.)

Below I have attached a circuit which divides the voltage and gives the output to an input pin of a microcontroller. Input voltage = 24V The resistor R0012 is for current limiting. The Zener diode ...
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Set multiple pins to different GPIO ports

I am using an STM32F4 discovery board and I have the following array v ...
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2answers
43 views

Voltage from IO pin at max current

I'm trying to use an ATTiny84 pin to power an LED. I initially thought that I would get around a 3 V output at all voltages, but there is a graph in the datasheet showing that that isn't the case: ...
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Analog digital pins

What is actually meant when someone says that a pin is digital and it cannot be used as an analog input? Are there any differences at the physical level, that is to say, the analog pin connected to an ...
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58 views

STM32F4 I/O Max Voltage Input

I'm having trouble understanding the max voltage input voltage range for an I/O pin on a stm32F11 when powering it with 3.3V.I'm want my STM32 to communicate with a 3.3V input signal and need to know ...
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Microcontroller driver the gate of a mosfet with a pull up resistor to 12V

I designed a PCB to drive mosfets with a ESP32 micro-controller. The ESP32 will be connected to the PCB with wires from a separate PCB. When there is no micro-controller connected to the input of the ...
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498 views

MCU with ultra low energy gpio input [duplicate]

I am working on a project with an energy friendly MCU from Silicon Labs. The EFR32BG1B132F256GM32 to be exact. My goal is to use as little power as possible to maximize the lifespan of the CR2032 ...
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1answer
125 views

Simultaneous reading of multiple I2C devices with the same address

I'm a teacher of a secondary school in the Netherlands. My students are working on a sun sensor placed on a moving object, with which the attitude w.r.t the sun is determined. A couple of ambient ...
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Capture GPIO pin values with STMA32 and DMA

I am trying to capture all GPIO_C port pin values at a time when PA0 pin goes low. I am using STM32F091RC micro-controller. But I cant figure out why ...
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376 views

Do I really need the N-MOS driver here?

In this circuit I am wondering if I really need the n-channel mosfet to control my dual p-channel MOSFET. I think I can drive this straight from the micro. Just want to second opinion before I modify ...
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with a L298N controller I need to “warm up” the motor to get it to run without stopping, why and how to do it with python

I understand that this will be a very trivial question but I cannot find an explanation online, probably because in my ignorance I'm asking the wrong question, to support my explanation I'm leaving ...
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I fried my Raspberry Pi while using L298N but I don't understand why

Everything seems to indicate that I fried my raspberry pi: the green light wouldn't turn on, I changed the SD card for a new one but it still didn't work. That is a shame because I was having a lot ...
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120 views

Problems reading a signal with a MCU (TM4C123GXL) input pin

I'm tring to read a signal generated by an op. amp. with a microcontroller through an input digital pin. All signals I'm working with are DC. The op. amp. is connected to a light sensor so that it ...
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1answer
70 views

Problem with setting usart by registers

This is the code. I'm using stm32f103c8t6 and I want to communicate with a Bluetooth module (Hc-05). I'm new with STM and I'm using registers and want to send just 65 for a test but it doesn't work ...
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158 views

Developing a Hardware Test Plan for a Microcontroller - Past Experience

I am using this Microcontroller using 3.3V for power. Using GPIO pins to drive some LEDs and send some ports for sending UART, LIN signals. I'm using a 16MHz crystal. Can someone tell me what the ...
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55 views

Pullup resistors value of STM32F103C8T6 GPIOs too weak, why not more flexible?

I'm trying to get a keypad to work, writing my own library (just because I want to learn it, and later use the keypad). For the columns I need pullup resistors, and I initially selected the internal ...

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