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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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Reasons for having MCU pin-states default to pull-up/down out of reset

On many MCUs, pin-states default to tri-stated (a.k.a. analog inputs) when the MCU resets so as to not affect the circuits they are connected to until software configures the pins. The tri-stated ...
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MSP getting powered up from GPIO

On a demo board I have, USB 5V rail is connected via a resistor divider to one of the GPIO's of MSP. MSP itself is powered from PCIE 3v3AUX rail. In one of the cases when the board is not connected ...
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Breakpoint Alters PIO Interrupt Behavior - ATSAMV71

So I'm baffled by this... I'm working with an ARMv7-M microcontroller and GCC compiler, debugging some code where I'm trying to enable an interrupt. I'm trying to do the following: enable an ...
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How to convert a 3.3V signal to 5V for a Mosfet gate

Based on the question 4-5-v-on-gate-of-mosfet-while-switch-open I ask this more generic question. Main project: I want to create a 16x8 (or so) multiplexed LED circuit Sub project: Creating a 2x2 LED ...
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Multiple inputs for driving a reset (RST) pin

I have an active high reset (RST) pin that is connected to a push-pull output. I am trying to connect another input to this RST pin, but this input is unable to drive the RST line high. Is this not ...
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STM32F4 Fewer Pin Mapping possibilities for ADC inputs

For STM32F405 100pin package, its datasheet page 39 and ref. manual page 388 as well as CubeMX shows that there are 3 ADCs each share 16-channels as shown in following images. Although it is not ...
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TVS diode selection for 3.3 V GPIO

Please refer to my project architecture in the image below: Power supply is isolated flyback smps type. GND is not connected to Earth or Neutral of 220 VAC. All parts of circuit are powered up with ...
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How to control single 12V LED with 3,3v GPIO? [duplicate]

Heyo! I need to control single 12V LED using Raspberry's GPIO To be more exact, I need to connect 12V LED & push button to 3.3v GPIO in order to control LED (on/off) and read button push events. ...
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Protection against ESD/EFT/Surges

One of my project architectures looks like this: GPIO / 595 output / 12 VDC wire lengths will not exceed 25 cm. I have faced MCU lockup issues due to EFT in the past and want to make sure this ...
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Unable to Read GPIO on Atmel SAM4L

I can't believe that this isn't working for me. It should be straightforward, but I've spent the afternoon on it & can't see where I'm going wrong. Hopefully someone will see my obvious mistake. ...
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ST-LINK and PA13,14 Pins on STM32F407

If I use PA13,14 pins for flashing my MCU via ST-LINK programmer then can I also use these pins as GPIO in the same circuit? Will that not disturb the ST-Link if some analog or digital circuit is ...
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5V Current Transducer to 3.3V Analog GPIO Input

I am trying to find 3.3V variant of the 5V Current Transducer LTS_25-NP but so far no success. Is it possible to interface this 5V analog output to 3.3V STM32F407 analog input GPIOs? Edit: I want to ...
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NRST pin of unpowered STLINK V2

I am using the STLINK from a Nucleo board in order to flash and debug a STM32F7 MCU on a custom board. Everything works fine except when STLINK is connected to my custom board AND unpowered. Indeed, ...
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Interfacing GPIO 3.3V to 74HC04 5V

Will it be safe if I connect STM32F407 GPIO outputs (Vdd=3.3V) to 74HC04 hex Inverter inputs (Vdd=5V)? What is the best recommended method to add an inverter at the output of STM32F407 MCU? edit: ...
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GPIO Configured as Input OR Output

Is it possible to identify looking at the schematics whether a GPIO pin is configured as Input or Output pin for the case in following image? PIN93 and PIN94 of a MCU are connected directly with ...
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How can I check if an IO pin is dead?

I've been playing around with I2C for a couple days now with a DE10-Nano dev board: I'm implementing an I2C master in CLaSH so that I can talk to the HDMI encoder chip, but for now I'm talking to an ...
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Limiting the current into Raspberry Pi GPIO pin

I have a dc dc regulator which can output .35A Current at 3.3V. I just need to check that the voltage it is producing is 3.3V by connecting it's output into one of the GPIO pins of Pi. So i was ...
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low voltage pin in Keil (ARM) debuging?

I am going to work with one TFT LCD 2'8 (ILI9325 Driver) with STM32F103RE ARM MCU. So I have one example program in Mikroc for ARM ( Microelectronica Co), which is working good, you could download ...
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Presence of voltage in Mega+Ramps GPIO pin

I am using Arduino Mega + RAMSP 1.4 with Marlin firmware to control my machine(not exactly a 3d printer). Marlin has gcode M42 P20 S255 ==> Turn on 20 the pin of ...
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Is it possible to get the full spectrum of a RGB diode (3 prong input) through 1 GPIO pin?

I apologize if this question is not well formed. I am an amateur in this field. I have the requirement to independently control a plurality of RGB diodes from a single microcontroller. Each diode has ...
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How to use a transistor to drive strings of LEDs from GPIO pins?

This is similar to How to drive a 20mA LED From a 4mA max GPIO Pin except that I need a little more hand-holding in order to understand what is happening. For background, I'm a software engineer and ...
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How to test my GPIO code?

Should I be asking this on Hardware Recommendations? That is – do I need some sort of test device? Or, hopefully, I can just my laptop … I am developing a vending machine controller, as a hobby ...
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Trouble with SO on MCP23S18 spi gpio expander

I am unable to get a signal out of the slave out (SO) line of an MCP23S18 For those not familiar it is a slave SPI gpio expander. Clocking in 32 bits, as it goes 16 bits set up, 8 bit opcode, 8 bit ...
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Controlling the brightness of LED panel via GPIO pins

I'm trying to control an LED panel like the one in this link. I notice it comes with an LED driver. But what I'm wanting to do is to be able to control the brightness of this light through the GPIO ...
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Controlling the power supply of a bluetooth module via GPIO and a transistor

I want to be able to turn a Bluetooth module on and off via a GPIO pin of a microcontroller. My first approach to realize this with a transistor is shown below. Is this approach correct? If not, how ...
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GPIO connected as open-drain to opto-isolator's cathode

When connecting GPIO output pins (RPi, uC, ...) to an opto-isolator, the classical way I know is the following (at least I understand that it can roughly be depicted like that): simulate this circuit ...
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MCP23S17 Interrupt Issue

I am having issues with interrupt setup on MCP23S17. Not able to set up the INTB line properly. I have an external 10K pull up resistor connected to the line and 3 input buttons connected to GPB0 - ...
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Connecting multiple Net Labels to same Net Wire

I am using Altium Designer 17. My schematics is Hierarchical and divided into multiple sheets. Few sheets have microprocessor ...
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1answer
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GPIO input state with undefined voltage

I am using PIC32MX350 series controller, on one GPIO , that is defined as input , and input that pin goes form one SMPS (PN : - PSC35 , IO Name :- AC out). Since SMPS IO is open drain we add a pull up ...
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Reading GPIO configuration (Cortex M4 ATSAME54)

I'm writing some diagnostics for a Cortex-M4 -- in this case an ATSAME54. I'd like to be able to read the configuration of individual GPIO pins, namely: bool level enum gpio_direction direction [IN, ...
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OSError: [Errno 121] Remote I/O error or pigpio.error: 'I2C read failed' on MPU6050

So I use MPU6050 to get acceleration from stepper motor linear rail movement(steper motor working in thread, I use pigpio for the motor) by make the MPU6050 can work on threading and it can show data ...
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Receive same GPIO input signal on multiple raspberry's from one source

I'm having 7 raspberry Pi's 3 connected to 7 screens, running an python 2.7 app to download different images from google drive, every raspberry has different images. Geeqie is displaying those images ...
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Sudden raspbery pi power cut or random long delay when running stepper motor using pigpiod

So I wrote another program that can run stepper motor nema 34 using leadshine DM860 driver and this is the example of my code: ...
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AttributeError: 'NoneType' object has no attribute 'send' pigpiod

So I create an another program that can run stepper motor clockwise and counter clockwise with a ramp up and ramp down in there and adding limiter switch on GPIO 16 and 26 to stop the ...
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Why does my GPIO only show 2V when connected to the Gate Termina lof NTE2390?

I've got a circuit set up with a motor that matches this diagram. When a 3 V power supply is connected to the Gate terminal, the motor spins. However, when I replace the 3V supply at the Gate ...
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Ground issues when switching AC with 2 MOSFETs

For a DIY smart home project, I need to switch 24VAC from a microcontroller (in sporadic 200ms pulses, drawing 1.3A, to switch a bistable latching relay). The most cost-effective way seems to be 2 ...
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STM32F103 PC13 on Output mode not work

I using STM32F103C8, I want to use PC13 in GPIO mode (RTC is active). The register ODR13 changes, but the logical value of the PIN does not change. ...
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ULN2003 Saturation Voltage help

I'm busy designed a PCB that will use a Raspberry Pi's GPIOs to to drive several optoisolators. Additionally I'm also interfacing with an IO module that works with HIGH > 1V. Because of the number ...
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What are the optimal methods for controlling specific header pins via Micro-USB?

Besides buying a Raspberry Pi with GPIO, what is involved in creating a circuit board that can send data to specific pins through a micro-USB cable, as well as read from data from sensors? I am open ...
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Can you simulate a GPIO input on STM32F0?

I'm trying a variety of things out with input pins and customized timers on the STM32F0. All timer functions are alternate functions on the pins and therefore you cannot use the user button (PC13 on ...
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Powering ILI9341 LCD from MCU IO pin

Looking at the ILI9341 datasheet Electrical Characteristics, I just can't find information about power consumption. The information is also missing from the LCD module datasheet (ER-TFT024-3). I know ...
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Let two LEDs blink with Raspberry Pi

I have written a simple Python program which runs on a RPi to make an LED blink. For that I connected my RPi using GPIO 23 with the anode of the LED, and before going back to ground, I added a ...
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TIVA Injection Current

I want to understand how the GPIO pins of my TIVA uC will behave when the voltage is above Vcc or below GND. I assumed I could just Ctrl+F "injection current" in the datasheet and that would give me "...
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1answer
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How does integrated displays controlled by the computer?

Consider a run off the mill pc: lcd displays connected, you have brightness control in the menu of the lcd. And some other stuff like color temp and modes. Now consider a laptop, AIOs and kiosk PCs. ...
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How to interface SN74 buffer with microcontroller into another data bus

I am hoping to interface a 3.3V ARM M4 microcontroller into an already established 5V data bus, and have it respond to interrupts to either read data from the bus or write data to the bus. The data ...
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1answer
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Command Line GPIO Access - Pin Types (Orange Pi)

I am trying to set GPIO pins to high and low state on an Orange Pi using the following command: ...
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Array to control individual GPIO's [closed]

I'm new to embedded systems and C programming. I am Currently trying to program a PCB using an STM32 microcontroller to control an array of 8 fans upon receipt of a single command. i.e 00001011 will ...
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Practical limits on Raspberry Pi GPIO pin voltages

I know the Raspberry Pi GPIO uses 3.3V, and you should never connect voltages higher than that to the pins. However, when connecting an I2C device I accidentally put 3k pull-up resistors to 5V (...
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water level sensor wetting current

i would like to connect a water level sensor* to gnd+pin on an mcp23017. the pin need to be pulled-up with some resistor. the internal pullup of mcp23017 are 100k if i have read correctly the ...
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Having trouble in GPIO output, 220 V to 5 V signal

I'm not an electric guy, I'm just trying to build a small circuit to sense 220 V with my Microcontroller (RPi). But I'm getting either 5 V or 1.3 V on a GPIO wire. I can't understand the problem. I ...