Questions tagged [io]
This isn't a useful tag since all chips have input and output ports. Avoid using it, please.
119 questions
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How to protect a μc IO pin that might see voltage when μc is off but must read it when μc is on?
I have a small voltage source which I'm using as a detector for power in another circuit. It connects to a microcontroller pin. Sometimes it's active when the microcontroller is not powered up, but ...
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What's UHS-II microSD card Pin Definition？
Pins 9-17 I don't know what description they are，and I need datasheet or diagram to know which pin Definition
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How does a Lattice MachXO3LF FPGA handle undefined IO states?
In the Lattice MachXO3LF FPGA, if an IO pin voltage is in between the thresholds for VIH min and HIL max, how does the FPGA handle this?
How does the FPGA handle if the undefined state was reached ...
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Lattice MachXO3 FPGA VIL and VIH of Mixed Voltage I/Os
The Lattice FPGA MachXO3 sysIO User Guide, page 12, under section "7. VCCIO Requirement for I/O Standards":
it mentions that an:
input buffer set up to be a 1.2 V ratioed input can be used ...
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Two PCF8574 detected but not the third PCF8574
I'll be using an Arduino Nano 33 IoT together with three PCF8574 IO expander boards. I've managed to connect two PCF8574s together and communicate to each of them individually at different address ...
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Testing an IC : IO PAD experiences 2nd-order ramping effect
The IO is a regular PMOS-PULL-up and NMOS-PULL-dn IO with series resistors on pull-up and pull-dn branches. The IO is input an clock signal around 50MHz and it experiences an approximately 2nd-order ...
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Current increase for IO Expander/Level Shifter
I’ve been designing a project recently that uses a level shifter/io expander. I’m trying to figure out the best way to go about increasing output current while still allowing the io to be ...
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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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3
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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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Control a large number of LEDs from minimal output pins
I am working on a project that uses an Attiny84 to control a large number of LEDs. The number of LEDs far outnumbers the number of I/O pins. What concepts and principles should I be researching into ...
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Crossing power (ground) domains on a PCB with a digital signal
I have a circuit with a common battery "ground" and a few non-isolated voltage regulators. In order to minimize electrical noise on the printed circuit board I've taken care to maintain a ...
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3
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188
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DS3231 RTC interfacing with Raspberry Pi 3B
I want to interface a DS3231 RTC module with my Raspberry Pi 3b model in a project. As we all know this RTC module supports only I2C communication, where pin no. 3 and 5 of the Raspberry Pi are used ...
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Why do all I2C devices with a programmable address not use this clever feature?
I was searching for IO expander IC, I plan to use multiple such chips on the same I2C bus (in the future potentially more than 8). And I was surprised that almost all chips that I looked at had only 2 ...
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How to read HLDA pin DMA Controller 8237 with Assembly Codes [closed]
I trying to read HLDA Pin in 8237. But i can not find a literature(s) about it in Internet. In Assembliy codes.
The circuits is use for i/o cards in PCI or ISA BUS. addeds DMA Process with all. I use ...
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RDS - PLC wires
I'm an American but I'm changing some of my drawings to RDS (Reference Designation System) to make these drawings more similar to the drawings of equipment that keep coming in.
What is the proper ...
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LVDS vs driver strength in FPGA IO
In the FPGA, there is I/O constraints that can be done to configure the output buffer. Some of these constraints are like setting the output drive strength parameter, on die termination, output delay, ...
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STM32F078 I/O voltages
I'm working on a project right now and I'm building a schematic using the STM32F078. It's 1.8V. I know it has the analog/digital separate power supply of 3.6V max which on the data sheet is called ...
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Port expander with high side switch ground dilemma
I have a design wherein the basic idea is to control individual LED strings and dim (analog dimming) them using Pi Pico via I2C interface.
This board is the LED driver which will be connected to the ...
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set defined output state at start
I'm controlling a trigger system through fiber links. The optical transceiver for triggering the pulse that activate the channel is commanded by a port expander IC to which I send commands through I2C ...
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2
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How does programmed IO vs interrupt driven IO work? [closed]
I know how programmed IO and interrupt driven IO work but I am confused if I am right about their working or not:
This is the flowchart given in this site: https://slideplayer.com/slide/265620/
I used ...
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ESP32 digital IO output inconsistent voltage
I have a problem which I have been fighting with for several days now. I can't see any possible solution. Maybe someone could give me push in the right direction, that would mean a lot.
I ordered 5 ...
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Questions about MMIO
Any CPU has address pins which form it's physical address space.
Some peripherals, like ram or flash can be classified as one big data register which is mapped directly to CPU address space. On the ...
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Industrial IO board ST X-NUCLEO-PLC01A1 - design features
For a project I want to buy an X-NUCLEO-PLC01A1.
So I studied the schematic and datasheets (CLT01-38SQ7)(VNI8200XP), but there are still some points that confuse me.
What is the purpose of D20 - is ...
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What really limits off-chip I/O? Capacitance or Inductance?
To my understanding, the crucial limiting factor for off-chip I/O is bondwire inductance, something that seeks to be minimized with BGA, flip-chip bonding etc.
The rationale is that an RC wire model ...
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Serial I/O Not working on DE5-Net
I'm porting a circuit from DE0-Nano to DE5-Net.
I'm currently implementing a simple test circuit for the DE5-Net. So far I can program the user LEDs and the two Hex Displays.
However, I don't seem to ...
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Can I/O expanders be used to drive a Camera or LCD?
After searching around it seems that I/O expanders are used mostly to drive LEDs or buttons.
Could something more complicated like an LCD be driven without bit banging? I.e. are there typically ...
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Connecting I/O peripherals to general purpose (evaluation kit) MCU
I'm new to electronics and am interested in playing around with an evaluation kit like this one.
It looks like those pins sticking out of it are GPIO pins, but I can't find a picture that zooms in ...
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5
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4k
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Device to power either a red LED or a green LED
I have a green LED and a red LED. I want a sort of switch to turn either the red LED or the green LED on.
For example: When the switch is off, the red LED is on, but if the switch is on, the green LED ...
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326
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IO port register whose address is software defined (x86)
I want to do something that I assume must be fairly common in digital logic/bus design. It’s for a new expansion card for an old 8088-based computer. This isn’t some kind of college homework project.
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What is specification connectors used in dji manifold 2
i'm Filipe
I'm looking about what is connectors specification used in DJI manifold 2, unfortunately in datasheet there is'not information about this specification only it talks about communication ...
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3
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How do Shelly products detect button presses?
I've been playing with home automation for a while now (mostly Sonoff) and recently discovered Shelly.cloud. I'm fascinated by the fact that most of their relays use a mains connected switches to ...
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What affects a microcontroller IO's VOH_min and VOL_max?
What affects VOH_min and VOL_max? Is it just the current being sourced/sunk by the pin? Or are there manufacturing variances or temperature effects etc that can swing the output voltage away from ...
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IO clock pin far from design, reduce propagation delay
My design is deployed around a particular tile in the FPGA, mainly because of a gigabit transceiver that is located there.
However one of the clocks needed for the gigabit transceiver has to come from ...
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3
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301
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Why 8051 microcontroller uses four different ports for I/O instead of using address bus and control signals
8051 has four ports for I/O .Therefore four peripherals can be connected to it at a time .
My question is why doesn't it use the address bus to activate a specific peripheral ...and then use the data ...
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How to interface IO Link devices without any gateway/additional circuit
I am planning to use a distance sensing device like this distance sensor with a mini computer like the Raspberry Pi or the Jetson boards. I read that the interfacing requires additional gateway like ...
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What happens to ESP32 module IO pins when it is connected to ground but not to power?
I have a circuit with several modules that share a common ground. One of them is a common ESP32 dev board. It looks that if I connect something to an IO pin of the ESP32 then it pulls it down ...
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Regarding PLC and several input/ output modules
I have to use more than 40 servo motors and 20+ load cells using PLC. But the problem is that I have to use many I/o modules ( that is costly and hectic). Can I reduce the no of I/o modules by any ...
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116
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Multiplies I / O reading with interruption in stm32f767zi
I am developing a board where 40 low I / O ports will be read, and I would like when I detect a low border to activate interruption for reading the port. in the documentation it says that "Up to 168 ...
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Can i use a single NodeMCU IO pin to give select input to multiple 74HC157 ICs(2x1 mux ic)?
I have atleast '6' 74HC157 ICs in my design, with the select lines of all the 6 ICs tied up together(Fig1).I wish to give a logic high or logic low to the select line using just one NodeMCU IO pin. ...
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4
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Memory Mapped IO and IO Mapped IO
I am revisiting Microcontrollers and Microprocessor concepts.
Yes. I know this question has been asked many times like here and here. I have also visited many sites regarding this concept but still I ...
user220456
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what's that symbol in the attiny13a I/O schematic? [duplicate]
I was reading the ATtiny13A datasheet and I can't figure out what's that symbol in the general digital I/O schematic. I've circled it the figure below.
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pulled down io protection from overvoltage
I need to protect my IC's io form overvoltage(default is 5v). The pin has the capability to source 10 mA and sink 25mA
I tought of using a tvs diode(between pin and gnd) and a resistor(330r from pin ...
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Altera Cyclone IV Setting Impedance
I'm trying to learn how to implement a 3V LVTTL interface using a Cyclone IV E (EP4CE10) FPGA. However, I would like to ensure that the input/output impedances of the IO is at 50R. I see that it is ...
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How should I match the impedance?
I have a problem for getting the 4-20mA input via 1769-IF8 I/O module. My field device is in good condition, but my AI card doesn’t respond. When I have been browsing about it, most of them said, the ...
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thoughts on reading only one changing GPIO with accurate time amoung huge number of digital Inputs
I am trying to read a huge number of digital inputs (129 to 800 and maybe more) at the same time. the sampling rate should be around 500K samples per second but I only need to read one of these inputs ...
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349
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Use PCF8574 switch selection multiple SPI slave devices, is it possible?
My project use esp8266's SPI communicate with MCP3208 and SDCard, to select which device to be communicated, that device's CS pin need to set low, and set high to another device to disable, right? My ...
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Isolation of SD IO pins during off state
I have a project at the moment that uses a PMOSFET to switch the supply to an SD card. According to the SanDisk SD datasheet available here:
Because there are clamping diodes on the CMD, CLK, and ...
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Xilinx Line <read_line> has not enough elements for target <input_b> for the file with more than one line
I have a file each line of which includes two 9 bits inputs. Here is an example of this file:
input_vectors.txt:
...
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122
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IC enable pin control with Atmega 328p
I want to control the FP6293 ICs enable pin with the Atmega 328p pin PD5 (configured as digital out). The EN pin (active high) on the IC is rated at max 6V with a minimum HIGH voltage of 0.96V. As the ...
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Not All I/O Pins Work for Nixie Driver on Arduino MEGA and ATMEGA1284PU
I am tearing my hair out, and help would be immensely appreciated.
I am developing a nixie RPN calculator. I am using nixies being driven by K155ID1 nixie drivers, connected to an ATMEGA1284PU. I ...
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