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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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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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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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39 views

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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28 views

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
50 views

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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47 views

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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Smoothing steper motor movement when chage the direction

So, I'm driving a NEMA34 bipolar stepper motor and it is being driven by a DM860 leadshine. I create a program in raspberry pi using pigpio library, the program that that make stepper motor change ...
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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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54 views

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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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
55 views

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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110 views

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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102 views

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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1answer
54 views

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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2answers
882 views

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 ...
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1answer
110 views

How does a CPU interface with GPIO pins?

I am trying to implement a simple mips1 clone in Verilog at the moment, works all fine in simulators but I also want to run it on an actual FPGA. Basically I would like to send/receive characters to ...
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148 views

How to measure voltage of a floating GPIO (Raspberry Pi)

I would like to measure that voltage of a floating GPIO on a Raspberry Pi 3. When I use a multi meter or an oscilloscope it looks like the pin is pulled to ground and shows 0. Another way of asking ...
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Is there a way to write a generic GPIO code for MSP430?

I'm currently working on an MSP430 board and I'm trying to create libraries for it so I can easily use them on my project. I'm starting with basic Digital I/O functions. Say for example I need to ...
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Generate TCP/IP packet on physical button press

Generating a packet, UDP on a specific port, is easily done with a PC, Raspberry PI, etc. But is there a single chip way of doing this? I THINK what I need to look into/learn about is PIC. But I'm not ...
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1answer
108 views

Why can't I route the same signal to multiple pins on an STM32F407?

I have a periodic signal which I want to use as a trigger to two timers - TIM8 and TIM2. When the signal goes high, TIM8 should start running and TIM2 will be clocked once. TIM2 will be configured in ...
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134 views

GPIO state of MCU (AVR) with no supply voltage

In general: what state do the GPIOs of a MCU (an AVR in my case) have when there is no supply voltage and the MCU is "off". Am I right that the pins are floating as there isn't any "reference" for the ...
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69 views

Care to be taken while connecting 220 VAC to MCU pin

I have a product with a non isolated power supply which has 220 VAC live line as the GND reference: My MCU receives 3.3 VDC from the same circuit. I want to detect the presence of 220 VAC (same ...
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32 views

Behavior of an ECU Digital Output (0-24V) to another ECU (pull-up i guess) input

Recently i had to control a functionality of an ECU using a separate system (another ECU). ECU "A" provides an input pin which if measured in open circuit shows 12V, so i guess it is a pull-up input. ...
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1answer
116 views

Understanding atomic writes to GPIO on different ARM Cortex-M's

This video succinctly describes why the read/modify/store has potential problems when it comes to interrupts. Very clear and understandable. He uses the TI Stelarris Cortex-M4 as a teaching board ...
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173 views

STM32 pulled up GPIO pins work stange after being connected to the ground

I use stm32_smart v2 development board and try make a cheap and reliable 7 bit input interface using 7 jumpers from GPIO to the ground. Internal pull up resistors are used. The first time I did not ...
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1answer
176 views

STM32F303 Microcontroller open drain GPIO, Can it reach / be pulled up to 5 Volts?

I hope you are all doing well... :). I'm working on a project with pulse width modulation however I need my logical high output to be 5V. However, as my Vdd is 3.3V, the output high level is ...
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149 views

GPIO on Nvidia Jetson

Currently, I'm working on a Invidia Jetson TX2 dev kit. I'm trying to power a 12V 2A LED from a 3.3V GPIO. My current system uses a 12V relay with an optocoupler (generic Arduino One), but I'm trying ...
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171 views

STM32F103 - Single pin shorted to VDD?

I have a custom STM32F103C8T6 board. Long story short, the MCU works fine, I can connect to it, program it, read sensors, toggle GPIO etc. The problem is that, one of the crucial pins seems to be ...
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5answers
170 views

I2C monitoring without Microcontroller [closed]

I am trying to read data from an I2C connected touch sensor. Specifically the Azotec IQS266. I plan to preprogram all of the settings the way I want them, and then not touch them again after that. In ...
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1answer
71 views

Common signal line

I already have a solution for how to prevent polling for RS485 (question), however since I will eventually maybe have quite some devices and like a fast latency, I think I rather want an extra '...
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46 views

Digital IR Distance Sensor - Too Sensitive

I am building a few productivity timers that will be used on an assembly line to track the pace of operators as they work. The assembly line consists of a long frame with rollers spaced every 6 inches....
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2answers
110 views

Switch a differential I²C bus section, controlled via I²C

I want to separate a section of an I²C bus, controlled via an I²C message. (Similar to an I²C bus switch/multiplexer like e.g. PCA9540.) Indeed the I²C bus to switch isn't a plain vanilla I²C bus, ...
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191 views

GPIO push/pull and pull-up resistor?

I have a question regarding the behaviour of a MCU's GPIO pins when configured in a certain way in hardware and software. In this case I am using a dsPIC33EP, but I believe this question is generally ...
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73 views

STM32F103C8 GPIO Ports A Through G

I was able to get dwelche's blinker01 example to work fine; thanks yet again Old Timer! I headed over to the reference manual to trace through how that code works, and it's easy enough to follow. 1) ...
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72 views

Best way to handle 100 GPIO on AT32UC3C0128C

I want to monitor 100 GPIO pins on the AT32UC3C0128C and indicate the changes on the USART (RS-485 transceiver). In the code snippet below, I have set one of the pins as an input with the internal ...