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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Three wire remote controller - wiring to two GPIO pins
My remote camera trigger has three wires (red, yellow, white). The white is shared, and the trigger can complete two different circuits by shorting it with either the red or the yellow cable. One of ...
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Detecting SCL/SDA ports
I am working with the EFR32MG24 Wireless SoC Family. There is a controller and multiple sensors with custom cables and connectors. For flexibility it would be desirable to connect the cable two ways, ...
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Slave SPI not firing interrupt
I have 2 STM32F407 discovery boards for which I'm trying to setup a multi slave SPI bus. The first slave is working but the other one is making problems once I connect the second CLK input onto the ...
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Design circuit for control line operated by GPIO output pin
I'll lead with the questions.
The use case and objective are below if interested.
Landscape:
There's a manufacturer provision to support synchronous captures for (2) and only (2) of their cameras: any ...
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Internally connecting pins on microcontroller
I am working on generating passive LCD waveforms myself using a microcontroller, and am noticing that proper LCD driver hardware has only one set of resistor dividers for generating bias voltages and ...
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How can I read the value of an open drain pin connected to an LED
I'm developing a circuit with a charger inside. The charger has 2 STAT pins that indicate the functionality of the board (charging, standby, fault, etc.)
As the datasheet suggests, I've connected two ...
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How are different GPIO frequency modes implemented?
An MCU GPIO's slew rates may be increased, or decreased, and this allows setting the maximum GPIO switching speed. But how is it implemented on hardware level?
I know that those outputs are ...
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Connecting GPIOs on two boards with independent power supplies
I'm trying to design a board that will accept UART/8N1 input from another board at 3.3V. While the two boards share a common GND (obviously), they otherwise have totally independent power supplies: ...
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MTCK and MTDO pins initialization on ESP32S3
I'm currently working on a project using the ESP32-S3 chip, and I've decided to use MicroPython for my coding. In my project, I have connected GPIO 39 and GPIO 40 to relays for various operations. The ...
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HIgh GPIO LOGIC with optocoupler
I want to know if my high side logic from 3.3 volt esp32 is right about linking a led on a gpio output to an optocoupler
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Designing a Switch to Protect ADC from 5V Signal
I have a question regarding the implementation of a switch between an ADC and a 5V tolerant GPIO pad, as described in the STM32 manual. Here are the relevant images for reference:
In my design, I ...
Fred Nguyen
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Which is the default state of MCU's GPIO before initialization?
I have a microcontroller that enables an IC. This IC would be enabled when a logic 0 is set in its enable input pin. So, one microcontrollers' GPIO is connected to that pin. My question is, before ...
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How to debug a failing USART?
I have simple code which writes to the USART on a Nucleo board that is connected to ST-Link, and appears on my workstation via VCP over USB.
I'm trying now to port it to a STM32H735G-DK Discovery but ...
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How is the LCD on STM32H735G-DK connected, and how can I turn it off?
The STM32H735G-DK Discovery board comes with an LCD. I wrote from scratch (no HAL) a simple blinky code, and it works well. However, the LCD is on (and backlit) by default, without any code from me ...
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Driving a 12V ~500mA load with a 3.3V logic level special pin GPIO0 on a ESP07s and ULN2003
As some of you know GPIO0 is a special pin that needs to be pulled HIGH during start-up else the ESP07s enters flash mode.
Questions:
The pull-up to 3.3V works right? My thinking is that if I have ...
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Driving a 12V ~500mA load with a 3.3V logic level special pin GPIO0 on a ESP07s and MOSFET
As some of you know GPIO0 is a special pin that needs to be pulled HIGH during start-up else the ESP07s enters flash mode.
I've tried to read up, but it feels like I know too little to know what to ...
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How to construct an integer based on the binary input of 8 to 32 GPIO pins
I'm researching a sensor for a project that has multiple methods of returning a value, one of them being a parallel output system that breaks down the value into 16 bit binary and transmits each bit ...
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NPN Relay Driver Problem
I've designed what I thought would be a simple relay driver circuit to drive a relay with a raspberry pi GPIO pin (which is pulled down with a 50K resistor internally). In the circuit diagram, pin 6 ...
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KiCad Schematic Check
I just want to make sure that the schematic I had made was done so correctly, specifically the button configuration. I want a 10 kohm pull-down for each button so I want to make sure that I had routed ...
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GPIO vs GPIO-HD vs GPIO-FAST
I am using NXP S32K148 in one of my design. In the IO signal table I can see that for some pins, pad type is written as:
GPIO
GPIO-HD
GPIO-FAST
May I know the difference between these three?
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Pi Pico generating YPbPr-like signal for VGA monitor
I would like to generate TED-like signal for VGA monitor input (Analog RGB + H/V-Sync). This is basically 16 pre-defined chroma values with 8 brightness levels applied, encoded as 7 bits: ...
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STM32 - How to understand if GPIO is high current or not?
I'm working with the STM32F303 Microcontroller. The datasheet says that almost all pins are high-current, with the exception of analog inputs.
I want to select multiple outputs to drive the ...
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Using STM32 I/O pins as power supply
I'm designing a device where I have multiple sensors controlled by an STM32 microcontroller (STM32F030F4P6). It's a low power device that is supposed to work for months or years on single use ...
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1 GPIO for 2 LEDs
I'm designing a keypad with backlights and each button has its own indicator LEDs that will be turned on when a button is pressed. While the indicator LED is on, the backlight LED of that button ...
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Connection Raspberry Pi GPIO to a 5v signal that isn't powered by the Pi
I have a HBaseT Matrix (EL-4KPM-V88-A2416) that has 3.5mm mono (signal+ground) plugs that is used to send IR codes to HDMI devices (it would usually be connected to an IR emitting diode placed in ...
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STM32H750B-DK output pins don't work while using the display
I am trying to make a relay driver with STM32H750DB-K, so I could switch the relays with toggle buttons on display, but I have a difficulty writing on digital pins. I am working with STM32CubeIDE.
...
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How many SSR relays can be driven from a RP2040 GPIO
So I have tested and confirmed that I can use an G3VM-61GR2 solid state relay to switch an amplified audio signal. I would now like to understand how many of those I can safely drive from the GPIO of ...
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How to isolate multiple 24 VAC to 5 VDC power supplies (buck converters) that are all powered by a single main transformer with a common pole?
Basically, I am trying to test multiple relay controlled outputs that are all 24 V outputs. One pole of the transformer is going into a relay for each device and the other side of each device is ...
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What is the purpose of "IO38_DBLTAP" on this ESP32-S3-MINI dev board?
I was examining the Adafruit ESP32-S3-TFT feather board and saw this IO38_DBLTAP section (bottom right of image).
It looks like a pulldown resistor and a decoupling capacitor, but I'm confused as to ...
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Why is my GPIO High Voltage lower than expected?
I have a GPIO pin tied into 3 LDO enable pins - when HIGH, turns the LDOs on, and when LOW, keeps them off. It's a 3.3v GPIO pin, but I'm reading 0.9v, which isn't enough to turn them on.
Is it ...
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How to interface 6 HC-SR04 ultrasonic sensors to Raspberry Pi 4
I am a beginner to Rasberry Pi and working on a parking warning system for a go-kart. The plan is to use 6 ultrasonic sensors (3 at the front of the kart, wired to one of the breadboards, and 3 at the ...
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Buzzer circuit sanity check
I am trying to establish if this buzzer circuit going to perform as expected
MPU: STM32 running at 3.3V, input will be coming from a GPIO pin that has a timer channel on it
Buzzer: A passive magnetic ...
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UART isolation with opto-coupler
I've got two devices running on different power sources and different grounds.
I'd like to connect them together through a Serial connection (UART TTL) at baud rate 460800.
Both devices have 3.3V UART ...
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TB9051FTG OCM Output Connection/Motor Encoder Outputs to STM32 Micro GPIO Input
I am working on a board to control a motor using a TB9051FTG motor controller chip. I would like to use a STM32F0304 to perform control of this motor.
https://www.pololu.com/product/4801
I plan to ...
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How do I run two NEMA 17 stepper motor from a 5v 3a powerbank?
The motors are 2 phased 4 wires 3.3v @ 1.5a, and I need them to run from a powerbank, how do I control and provide the motors with power? Which drivers are needed? They will be controlled by a ...
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How to connect 8-bit display to GPIO extender
I wanted to connect an 8-bit resistive touch display to a I2C GPIO extender which get's connected to a ESP-32, as seen in the picture
The display has a lot of pins, and I really need to know if I ...
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How to convert a varying 28~60V DC high into 3.3V？
I want to design a PCB, include a GPIO of a MCU detecting the on and off of a LED driver. The LED driver input is 220V 60Hz, the output varies between different LED within 28 to 60V DC. My intuition ...
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Driving LED with 1.8V GPIO
I’m currently making a board that needs to drive an external 20 mA red LED using a 1.8V GPIO pin. The LED is mounted on an separate board with a resistor as seen in the diagram. My board is supplied ...
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Creative dual NMOS and PMOS switch
I have quite a strange requirement for one of my assignments for a job interview. The goal is to design a shield to measure current through a 12V power rail. Part of this design is an on and off ...
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STM32 - While using SPI in write-only mode (MOSI), assign MISO pin to GPIO
While using HW SPI only for write purpose (only STM32 chip as master sends data through MOSI pin), is it possible to assign the MISO pin to general GPIO? I need it because the trace on PCB is already ...
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RC circuit to allow MCU to detect power toggles
I am trying to detect a power toggle event for a smart lamp I am building. Essentially, I want the lamp to behave differently when turned on after a long off period compared to when toggled on/off/on. ...
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Choosing waterproof or protected GPIO connectors [closed]
I am building a small device that, with the others, has several (at least 8) GPIOs and will be placed outside or, at best, in a possibly wet/humid environment. I am having a hard time finding a small ...
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Which is the equivalent voltage and resistance values in this circuit with pull ups at different Vcc?
I have two PCB that i have to interconect. In the first one it is R1 (pull-up resistor) in the second one is R2 (pull-up). The yellow rectangle represents the interface between boards. My questions ...
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How to PID control a 47 Ω, 8 W resistor with a Raspberry Pi and Python?
I have a Raspberry Pi 4B, a 12 V power supply, a 12 V air pump controlled by a MOSFET, a DS18B20 for feedback and a 47 Ω, 8 W resistor that we should somehow heat. Everything up to actually heating ...
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Possible ESD damage on UART pins between nRF52840 and ATmega1284P
I have devices operating from 2S Li-ion battery (max 8.4V).
They consist of 2 PCBs - the first one contains a 3.3V voltage regulator and an ATmega1284P, while the second one has MDBT50Q-U1MV2(nRF52840 ...
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Confused by i/o expander datasheet note re internal pull-ups
The inputs on the NXP PCAL6524 i/o expander can be configured with internal pull-up or pull-down resistors.
The datasheet states, "External resistors are required for inputs... that may float. If ...
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Can I connect a 5V tolerant UART interface to 3.3V GPIO pins configured as a serial port?
I want to connect the telemetry RX/TX pins of a flight controller running this microcontroller to a single-board computer, using the GPIO pins.
According to 1 (ArduPilot mapping), the UART port is 5V ...
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"Output only" - IO Expander Question
I see on the datasheet for the MCP23017 that the GPA7 and GPB7 pins can only be outputs per the latest revision.
Can anyone explain why this is? Is it okay to still use it as input, but just decreased ...
user220456
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Question on LED current and voltage
This is regarding this battery charger IC.
In the below image, the output low voltage on the STATx pin is given as 1V, but that is for 4mA of sink current. That translates to around 0.25ohm of ...
user220456
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STM32 output initial state problem
I am using the STM32 IDE and an STM32F4 board. When I power the board the output pins go high and then go low. How do I prevent this from happening? I want these pins to start low.
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