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 ...

learn more… | top users | synonyms

1
vote
1answer
46 views

can't assign PORTD a variable value on PIC18F

I'm using the following code to test some GPIO while I mess around with the PIC18F45K20 demo board. I realised something was strange when I couldn't increment a value and see it reflected on the LEDs ...
0
votes
2answers
57 views

Isolating GPIO's using diodes

Schematic The arrows are GPIO's I want to be able to close multiple switches at once in any particular order in order to manipulate GPIO's manually. I could give each GPIO its own resistor, but when ...
0
votes
2answers
78 views

Using a high resistance pull down resistor

I'm trying to make a circuit where closing a switch will change a GPIO from low to high, and I want to minimize current as much as possible to increase battery life. The chip I will be using is Nordic ...
0
votes
1answer
38 views

IAR STM8 LED Pin On/Off Flash

i tried to flash the LED of this controller: http://www.cnx-software.com/2015/01/18/one-dollar-development-board/ (as you can see, there is a led connected to PD3) with this code: ...
1
vote
1answer
34 views

How to use CMSIS to set up bidirectional Port on STM32F4

I'd like to use the GPIO_TypeDef an GPIO_Init to create a bidirectional Port on the STM32F407, some input pins, some output pins. Do I just run GPIO_Init twice, once for the input pins and once for ...
1
vote
1answer
48 views

Can't control RB10 (and RB12) of the PIC32MZ2048ECG064 as a 'normal' GPIO [on hold]

This is an excerpt from the datasheet of the PIC32MZ EC Family concerning peripheral pin select output mapping: I'm using the PIC32MZ2048ECG064. My question concerns RPB10. I would like to use RB10 ...
0
votes
1answer
15 views

sam3x8e gpio interrupt not working as expeced

I working on sam3x8e processor with atmel studio 6.2. I have configured two gpios for interrupt on falling edge as follows: ...
1
vote
1answer
38 views

Calculating resistor values for RPi circuit detecting AC current using H11AA1 and PNP transistor

I've got an electronic doorbell system (Aiphone IE-1AD) that sends a ~15Vac signal when the button is pushed. I used this blog post on detecting a signal on a similar door bell using a moteino ...
1
vote
0answers
42 views

Connecting encoders/SPI devices/LEDs/buttons to a Rasperry Pi

I'm trying to connect a model B rev 2 Raspberry Pi to a whole bunch of stuff to create a MIDI foot controller: Adafruit touch screen 20 switches (some foot, some encoder buttons) 8 x SPI LED drivers ...
1
vote
2answers
55 views

Send signal to gpio when 8V power drops

I want to be able to detect when a 8V signal goes low and send a signal to a raspberry pi over GPIO. A java app will be listening on the GPIO pins for any changes. I would check if the voltage drops ...
0
votes
1answer
51 views

stm32f401 hello world code

I've finished designing my STM32f401 board, but I can't get the GPIO to work. After looking for an answer on forums I still can't figure what I'm doing wrong ( Everything worked fine on the ...
1
vote
2answers
74 views

Powering a device through GPIO

I have a custom PCB based on imx28 (primary board). It receives external power via a cable. There is another PCB (secondary board) connected via GPIO to the primary board. The secondary board doesn't ...
0
votes
0answers
27 views

STM32F4 discovery GPIO-clock validation?

I have an STM32F429 discovery board I program it with : STM32-Matlab/target (embedded target for Matlab and Simulink), STM32CubMx (configuration tool) and the toolchain: Keil uVision5 (lite). I tray a ...
16
votes
3answers
1k views

Why do I first need to set a value and then direction of the GPIO in an embedded processor?

I have a full time job as a firmware engineer. I've recently been given a task to review GPIO configurations and change the settings as needed. I found a few pins that were incorrectly configured so ...
1
vote
2answers
52 views

How to read decade counter with minimum pins

I just obtained some of these counters for a project: They have five connections for each slice labelled C, 1, 2, 4, and 8. As you increment the digit, the pins for the appropriate binary encoding ...
9
votes
4answers
533 views

1.5V-rated MOSFET doesn't react to a gate input of 1.8V

I am not really an electronics specialist, but a software engineer (so excuses if I 'm asking stupid questions). I am trying to use a microcontroller GPIO output rated at 1.8V. When this pin becomes ...
-1
votes
1answer
150 views

Using GPIO pins as software I2C pins and finding analog value of those pins

I am using AT32UC3C microcontroller which has 64 pins. I am using gpio pin PB01 as SCK and gpio pin PA04 as SDA and ticking then manually high and low. These pins are configured as GPIO_OPEN_DRAIN and ...
1
vote
2answers
171 views

SMD vs THR Transistor for Relay

Designing a Relay control from a MCU's GPIO, there are some requirements to take into account. Coil Voltage: 3V Coil Resistance: [36-45]Ohm Relay Voltage: 250Vac // 30Vcc GPIO Voltage: 3V3 Max GPIO ...
0
votes
0answers
44 views

Testing an A-D converter of an ARM microcontroller

all. I am playing around with a development board that is using an ARM microcontroller and was wondering what would be a short and simple way of testing the A-D converter of the microcontroller. I am ...
0
votes
3answers
95 views

Digital Input Clamp Circuit Protection

To be able to connect some peripheral to digital input, I'm designing the circuit protection to avoid any possible failure due to over/under-voltage issue. So, I will add a clamp protection circuit. ...
0
votes
1answer
137 views

Negative voltage on input pins

Hope that someone can help me: I found a schematics to program microcontroller from Raspberry PI (http://mujweb.cz/tlc/rpp/) and modified it a bit (will use direct 12V and 5V power supply). I'm ...
0
votes
2answers
25 views

Low leakage current methods of initializing pin inputs at power up

Suppose I have an IC that has a standard level triggered input pin. I need this pin's state to be setup immediately at power on at a time when my MCU's GPIOs may not have established levels. What are ...
0
votes
0answers
64 views

How to configure digital output in Renesas RH850/F1L Microcontroller?

I need to configure pin AP0_14 for digital output. To achieve this I need to write 0 to bit 14 of 16-bit Port Mode Register. The physical address of this register is: 0xFFC103C8 What should be ...
4
votes
2answers
150 views

Why do I need this relay?

Hopefully I don't get torn apart for such a noobie question (but how else do you learn right?). I got a Raspberry Pi to hopefully learn a bit about electronics (and because it was 35 dollars). I asked ...
0
votes
2answers
59 views

Rising DC Voltage

I only have 3.3 DC Voltage on the pin of PCB and I want to supply a chip 5V. What are the ways to manage this? PS: The voltage on the pin is always 3.3 V and max current on it can be 50 mA.
1
vote
1answer
32 views

Atmega 328 with DS1620 thermometer chip. Why is a pull-up resistor needed on the DQ line

I think understand the purpose of pull up resistors in general but in this particular case the DS1620 datasheet says that in the output mode it sources a current of 1ma (see footnote 5 on the last ...
-1
votes
1answer
247 views

STM32F103 GPIO not working

I am programming for LPC microcontrollers (mostly LPC1769), for the past few months with success. I decided though to give STM32 series a try. I just received a no-name board using an STM32F103C8 MCU ...
2
votes
2answers
214 views

PIC18 GPIO switch from input to output(dual mode)

I have always wondered if it is possible to switch the port direction of the PIC GPIO during the course of the program execution. So, for instance I start with a particular port set as an ...
2
votes
1answer
295 views

Using NPN BJT with a P Channel MOSFET to switch 3.3V to 24V

simulate this circuit – Schematic created using CircuitLab I have some 3.3V I/O on a PC Board. When an output is switched on, I need to switch the 3.3V output voltage with a +24VDC and ...
0
votes
1answer
57 views

Safely connecting signal GPIOs

I'm using an STM32L053 MCU to interface to a poorly-documented PCB module (DRA818V). There are a couple of GPIO driven signals as well as a UART involved, and I want to make sure I'm doing things ...
0
votes
1answer
67 views

How to use 2 power supplies in my scheme?

I am building a device to send a signal from Raspberry Pi GPIO to a vibration motor. Here is how it should work: the RPI outputs 0v or 3.3v, and when it outputs 3.3v, the vibration motor should ...
2
votes
3answers
113 views

Why smartphone IR system uses an IC instead of GPIO?

I have an android based embedded system, and I would like to command ir controlled devices, such as tv, air conditioner, sound system...etc. I need both rx and tx. When I see examples on internet, ...
0
votes
2answers
99 views

Can a logic level converter be used as a replacement for a relay for detecting if a buzzer is currently active?

I have a small microcontroller (VoCore, runs Linux, has wifi and GPIOs) and i want to use it to hook into another system (basically a doorbell) to make the state of the doorbell-buzzer available over ...
0
votes
0answers
92 views

S_axilite port, how to deal with AXI GPIO

I have a block made in Vivado HLS that receives 3 parameters: 1-Map_in which is a matrix of values to be normalized. My objective is to connect it to DDR via AXI DMA 2-Map_out which is a matrix of ...
4
votes
2answers
77 views

Design Considerations for Raspberry Pi Expansion Boards

I am venturing into the space of designing expansion boards for Raspberry Pi's. I have done this for Arduino boards but RPi's are a different beast. From personal experience I have already had ...
1
vote
4answers
97 views

Use GPIO to disable voltage divider

I'm using a voltage divider to read the battery level of a wireless sensor platform using STM32L151. I'm shooting to use 20k for R1 and 10k for R2, to be under the 50k limit of the MCU's ADC ...
0
votes
1answer
137 views

tri-state / high-z / high impedance output with gpio input

The Li-ion charger I'm using (MCP73831/2) has a tri-state status output. The datasheet says that the STAT pin outputs High-Z when inactive or complete, and Low while charging is active. Whats the ...
0
votes
0answers
53 views

Reading analogue input using digital GPIO

I'm using soil hygrometer to measure soil moisture. Since I don't have adc I'm using This method. Please tell me how to connect resistor and capacitor along with amount of resistance and capacitance. ...
2
votes
1answer
260 views

What is drive strength a measurement of?

In microcontrollers and the like that have programmable drive strengths for GPIOs, said drive strengths are defined in mA. For example you might have a choice of 2mA, 4mA, 6mA, 8mA, etc. My ...
2
votes
2answers
114 views

GPIO Input fluctuating between high and low when no input is received

I posted this on the Raspberry Pi StackExchange but I feel as though it might be better suited for here, as the SE is pretty inactive anyway. I've got a fairly simple circuit that I've made where a ...
0
votes
1answer
84 views

DIY Photobooth: LED puck lights potentiometer suggestions

I'm building a Raspberry Pi powered photobooth, and want to add some lighting. I purchased this set of led puck lights, and would love to control their intensity from the Raspberry Pi, instead of the ...
3
votes
3answers
788 views

how to increase the voltage of a digital signal?

I'd like my Raspberry Pi GPIO port to communicate with a digital circuit that works at 2x the GPIO voltage. The communication will be at a relatively high frequency (up to 500kHz). The main question ...
0
votes
1answer
79 views

Transistor Switch to Pull to Ground (Broadcast GPIO)

I have a Sonifex Net-log audio recording device. It can be configured to begin recording on remote input. From the manual: The remote inputs and output can be driven by 5V logic. The inputs are ...
0
votes
1answer
133 views

Raspberry Pi B+ with relay: Lights change but relays don't click

I am using an 8 Relay module, bought from dx.com. It has no instruction manual... This board has 8 inputs (IN1,...,IN8) to control each relay, 1 VCC pin that requires 5V and 1 GND pin. I connected ...
0
votes
1answer
238 views

STM32F051R8: PWM timers don't work?

I'm working with MB1034B discovery board and STM32F051R8 microprocessor. I'm trying to output some PWM pulses using hardware timers. I use this tutorial (for STM32F4xx): ...
1
vote
0answers
73 views

STM32 F205VCT6: GPIO B Port 6 and 7 do not work?

I'm using the STM32 F205VCT6. I have a simple blinking LED program written in C++ with VisualGDB (and VS 2013 Community). It works fine for pins like A1 and E2, but it doesn't for B6 and B7, where I ...
1
vote
1answer
128 views

need for external i/o interfacing like in 8086 for latest processors

I am a student now currently learning about interfacing 8255 with 8086. For me the doubt is that, is there a need for external i/o interfacing like in 8086 for latest processors? what is GPIO ?
0
votes
1answer
64 views

More Current from GPIO

I'm working on a project that uses a GPIO port extender, but I need the ability to sink more current on the GPIO pins. There are 24 GPIO pins. Each pin can either be input or output. The pins ...
2
votes
2answers
352 views

Controlling 10 high power LED with a Raspberry Pi

I'm trying to figure out how to control 10 Luxeon Rebel LED (700mA) from a Raspberry Pi. I want to be able to turn them on and off from code, but I don't need to have two or more LEDs turned on at ...
0
votes
0answers
32 views

Explain to me how values are read with pullup resistors [duplicate]

In the above picutre, it seems to me as if when the switch is open, a voltage of VCC is on the input pin (i.e., voltage comes in through the resistor, to the input pin then back to GND through the ...