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 ...
4
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1answer
50 views
Advice regarding Remotely Operated Vehicle (ROV) control scheme?
Please let me know if this question isn't specific enough, I'll be happy to clarify. I am looking at various options for a control scheme for my underwater robot. I am in school and it is my job to ...
-5
votes
1answer
65 views
LED control using GPIO [closed]
I am using an industrial camera that has GPIO ports which I would like to use for turning LED plate off and on. LED runs on 24 V and 350 mA (between 350 mA and 1500 mA but 350 mA would be optimal).
...
-1
votes
2answers
77 views
Raspberry pi relay check from remote
I'll start saying that I'm almost noob on electronics, so that's why I'm here.
I'm looking for a smart way to check the state of an RF relay module remotely.
This is the relay module:
The module ...
7
votes
4answers
238 views
shorting a remote control pushbutton with GPIO and a transistor
I'm trying to control my garage door remote with a GPIO pin from my Raspberry Pi. Instead of driving a relay, it would be much easier to just short the pushbutton on the remote. Is this how I ...
0
votes
2answers
50 views
UART / GPIO bridge (bitbang)?
I like to control 8 switches (GPIO pins) individually via USB (on/off). To start i have a USB UART adapter (CP2102). By sending a command to the virtual port to control each pin i would like to ...
0
votes
1answer
129 views
What are some inexpensive easy to use SPI devices I can experiment with? [closed]
Introduction
I'm completely new to EE, but have decades of software development experience. I want to learn to interface with multiple SPI devices on a single SPI interface on a Raspberry Pi. I'd ...
1
vote
1answer
103 views
Power source select for Raspberry Pi
I'm creating a board which takes an external power source to drive motors which are controlled by a ULN2003A connected to the Raspberry Pi GPIO.
It would be nice if when the external power source is ...
2
votes
1answer
104 views
How to realise bidirectional ports in FSMC function of STM32?
I am using FSMC(Flexible static memory controller) function of STM32:reference manual.On page 494 of referencec manual, the data bus should be bidirectional. It is reasonable but i have no idea how to ...
5
votes
2answers
217 views
What's an alternate pin function on a microcontroller?
I'd like to know what "Alternative Function" refers to in the context of the IO ports of a microcontroller.
I don't need to know how to activate it when connecting to a peripherial, but I'd like to ...
1
vote
1answer
166 views
Faster IO on ARM Cortex-M3 (Sam3x8e) than PIO_SODR and PIO_CODR?
I have a very simple C program that toggles a pin on a Cortex-M3 board (SAM3X8E) with a 84MHz clock speed. I built this using Atmel Studio 6.1.
...
0
votes
1answer
278 views
How to wire a Normally Open Button to a BeagleBone Black?
This one should be simple, but I'm fairly new to this.
The button has a COM and an NO terminal. Beaglebone pins can only take 6mA, so I don't have much room for error. My question is, how do I wire ...
3
votes
2answers
283 views
Manual SPI interface on Raspberry PI
I am trying to control a MCP4131 digital pot from my Raspberry Pi using the
library here
Using the GPIO pins, I am "emulating" an SPI interface. I bring the ChipSelect pin to low, write my byte, ...
1
vote
2answers
70 views
Peak voltage rating means voltage drop?
This LDR is said to have Peak voltage rating of 400V in the description. Does this equal the voltage drop, meaning that I need to supply at least 400V or is it the maximum voltage value?
0
votes
0answers
37 views
Troubles sharing GPIO and JTAG on MC56F8006
This is my first time with freescale (DSC MC56F8006) and I am having some troubles related to GPIOD3 and GPIOD0 configured as digital output/input respectively shared with the JTAG. When I try to ...
2
votes
2answers
373 views
how can a GPIO of stm32 have many alternative functions?
I am working on the assignments of pins of STM32F103ZET1.
On page 31 of datasheet, it says that PA0 has many alternative functions: ...
5
votes
1answer
256 views
AVR Pin Dual Use: Input and Output at (seemingly) the same time
I have been working on a few different versions of a bicycle light control circuit which reads in various buttons and sets various outputs accordingly such as headlight, taillight, blinkers, etc.
My ...
3
votes
4answers
110 views
What happens to other component's power consumption, when uC is switched to low-power mode
Currently, I am using a uC (Atmel ATtiny85-PU20), which will eventually run battery powered, and I am trying to reduce power consumption of entire circuit to maximise time between battery changes. ...
2
votes
1answer
393 views
USB to GPIO module
I'm working on a project which involves having users press buttons on a webpage which the server needs to send onto a microcontroller in the form of a GPIO signal. The only ports available on the ...
5
votes
2answers
120 views
i2c external pullup kills communication
I am using an MCP23017 (which shouldn't matter tho) to extend the number of GPIO pins of an arm based linux computer using i2c-dev bitbanging. It all works fine with wires of a few centimetres.
The ...
6
votes
3answers
509 views
How to drive a 20mA LED From a 4mA max GPIO Pin
I have an IC that has an GPIO with which I would like to drive a LED.
Since the device will be running off battery, keeping the power use low (Zero maybe) while the LED is off as a priority.
The ...
0
votes
1answer
286 views
Beaglebone GPIO always return 1
I'm trying to get a button to work on my Beaglebone. I bought MAKE Volume 32 and tried to follow the guide in there.
But when I read the GPIO pin, do I always get 1.
I also tried to disconnect ...
1
vote
1answer
254 views
GPIO input connected to garage door button
I know there are other GPIO / Garage door related questions, but this is not a duplicate- I need to read the status of the garage door button, not a garage door sensor.
I would like to connect the ...
2
votes
1answer
184 views
Seven segment display becomes dimmer as more segments are lit
I've got a common cathode, two digit seven segment display (LDD-N512RI-RA) hooked up to the GPIO pins of a microcontroller (Coldfire MCF52233 DEMO). The problem is that the brightness of the display ...
5
votes
5answers
605 views
Pull-up and Pull-down Resistor Usage on Input or Output MCU Pins
Are pull-up/down resistors (whether internal or external) only needed for MCU INPUT pins? In contrast, an MCU pin configured as an OUTPUT "knows what level it's at" because it does the driving - a ...
0
votes
2answers
182 views
General Questions about PIC24 MCU Input and Output Pin Impedance, Voltage, and Current
I'm having a mental lapse. Try and help me make sense of a few basic things concerning microcontroller pins at the hardware level, please!
Correct me if I'm wrong… in the circuit of Figure 1 (see ...
2
votes
2answers
137 views
4 GPIO 16 Mosfets
I have 4 GPIO's and I have to drive 16 mosfets for my application.
MCU -> 4 GPIO -> something must be here(SPI mosfet driver??) -> 16 mosfets
I thought that if I have an SPI mosfet gate driver IC, ...
6
votes
3answers
1k views
Miniature Traffic Light with Raspberry Pi: Wiring many LEDs
Background:
I am a Civil Engineer specialized in traffic control devices and I have a small hobby project to build a scale model traffic light system. I can manage and control the traffic light ...
2
votes
1answer
118 views
NXP LPC1343 GPIO questions
I am an embedded SW developer who wants to get more familiar with HW design. I have an LPCXpresso board with an LPC1343 on it. I want to build some circuit around that. I thought I'll start by finding ...
2
votes
3answers
85 views
Reading value of bit in PxIN register
I need to get the value of an input but only need to get one specific bit. Im porting some software and can't seem to think of a way to get the value from PxIN for the microchip pic it looks like ...
2
votes
3answers
245 views
Can Arduino MISO be set as output?
So I designed a PCB which consists of an atmega328 controlling a digital potentiometer (MCP4131) using SPI. I stupidly connected the pot's i/o to the MISO (master in, slave out) pin on the arduino ...
4
votes
4answers
455 views
Accessing individual I/O pin on MSP430
Im porting some software from Microchip PIC (using the HI-Tech C Compiler) to TI MSP430, and in the existing code they access the pins directly with something like:
...
0
votes
2answers
178 views
how do I output through GPIO pins instead of RS232 from a Z8 Encore MCU?
I'm currently learning about MCUs in school (read: n00b) and I'm trying to fool around with the equipment at home. Problem is that I only have a netbook and don't have any serial IOs on it, so I have ...
0
votes
3answers
548 views
STM32F407 board [closed]
I started learning embedded programming. But there are many things which is not understandable!
There are many things like USART, GPIO, DMA, SPI, I2s, I2c....... and others.
I have manual and other ...
2
votes
3answers
266 views
Can I use I2C bus or GPIOs as I2C to connect I2C devices?
This question is regarding use of I2C Bus/GPIOs as I2C.
My application processor has three I2C controllers. Is it preferable to connect all I2C devices (obviously we can not connect more than 128 ...
3
votes
1answer
346 views
Measuring almost 1 volt between Raspberry Pi input pin and ground, why?
I'm trying to use a switch to to provide input to software running on the Raspberry Pi. I have software running right now that continually reads the input pin and prints the result. Problem is, even ...
10
votes
1answer
1k views
Getting a large number of (~100) digital output signals from Arduino
I would like to be able to control around 100 independent LEDs using an Arduino. The problem is that the Arduino does not have nearly enough pins that can be configured for this. What would be a way ...
2
votes
1answer
236 views
Need of External Pull Up/Pull Down for Processor I/O pins
For a particular I/O pin, its been mentioned in the processor data manual that there is Internal pull down, after power on reset, in the device with a default drive state of the pin as tristate(Z).
I ...
1
vote
3answers
1k views
Using GPIO in PC
I've got a simple project on host device that should drive 2 pins with high logic level (voltage 3.3V, 5V or 12V - doesn't matter) and wait for 2 others pins become driven high level by the peripheral ...
5
votes
4answers
296 views
Are CMOS outputs high-Z when unpowered?
If a microcontroller I/O pin drives an external MOSFET, and the microcontroller's power is turned off, will that MOSFET's gate be floating? I know sometimes a resistor is added to ground, but are ...
1
vote
1answer
492 views
GPIO and relay quesiton
I have a question about the YouTube video Raspberry Pi Controls Relay. It's about controlling a SainSmart 4-Channel 5V Relay Module. Is it driven directly off the 3.3V GPIO?
4
votes
2answers
698 views
Why does MSP430 have 2 capture signals for each capture/compare channel? Pin assignments recommendations?
Let's take MSP430G2553 as an example. If you look at the pinout in datasheet, you'll see:
P2.1/TA1.1
P2.2/TA1.1
One could think that those TA signals identical and multiplexed twice as a courtesy ...
8
votes
5answers
458 views
When IO is limited on a uC, how do you move the logic away from the uC?
For instance, if you had an Arduino with 4 digital IO pins, how could you independently light > 4 LEDs, or read the state of > 4 buttons?
9
votes
1answer
1k views
Plugging a LDR into GPIO pins of a Raspberry Pi
I want to connect a LDR into the GPIO pins of my Raspberry Pi, I know that Raspberry Pi doesn't have an analog-to-digital converter so what I want to do is to signal a HIGH signal (3.3v) on the GPIO ...
5
votes
1answer
819 views
Open Drain vs Open Collector
Is there a practical difference between Open Drain and Open Collector outputs, or are the terms used interchangably? If they are indeed different, what are the contexts where each is advantageous? My ...
2
votes
1answer
539 views
Problem writing to MCP23017 I/O Expander registers (i2c)
I am creating a basic cable tester device and using I2C to interface with two MCP23017 I/O expander chips.
In my code each MCP23017 slave has its own address and I can communicate with both of them ...
6
votes
3answers
568 views
Why would an input pin have both a pull-up and pull-down resistor?
In his answer detailing the various types of input pins, Russell McMahon leaves the following note [referring to input pins]:
there are special cases where a resistor to high and low at once is ...
3
votes
3answers
1k views
Using a 5V LCD screen from a 3.3V Raspberry Pi GPIO pin
I have an LCD screen which expects power from a 5V line, but I want to hook it up to my Raspberry Pi's GPIO pins which only supply 3.3V. What equipment do I need to increase the voltage from 3.3V to ...
0
votes
1answer
223 views
ARM: Read the value of an Alternate Function pin
I have an ARM STM32 where each GPIO pin can be configured as "input", "output", "analogue" or "alternate function". In "alternate function" mode, the ARM drives a lot of the logic for basic ...
1
vote
3answers
206 views
How to go from GPIO to digital signal?
I'm sitting here with my Raspberry PI and some other equipment that requires digital signal (high/low, enabled/disabled).
But the Pi only has a GPIO so to get it to work I would need a microchip of ...
0
votes
0answers
285 views
Need help reading pins on STM32F107VC
Recently I've started exploring ARMs by buying open107v board (based on the STM32F107VCT6) from China.
I've already figured out how to write to ports, but cannot get pin read. Here is a piece of code, ...
