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Questions tagged [io]

This isn't a useful tag since all chips have input and output ports. Avoid using it, please.

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0answers
22 views

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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0answers
32 views

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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0answers
94 views

High-level (Ioh) and low-level (Iol) output current measurement on I/O pins

I'm looking for a procedure to measure the High-Level output current (Ioh) and Low-Level output current (Iol) in a I/O pin for a IC. I'm planning to use a variable resistor tied to VDD or VSS. Maybe ...
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3answers
479 views

Can SPI and I2C be implemented using GPIO pins?

Can SPI and I2C be implemented using digital GPIO pins? I.e. can the SDA and SCK pins of I2C and the ...
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2answers
77 views

redundant output pins from MCU

I am analyzing a board with safety considerations. In one part of the circuit, PB0 and PB1 of MCU have been logical anded using an IC (PB0 && PB1). Does anyone have faced with such ...
1
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1answer
234 views

what are the differences between i/o expander, demultiplexer, decoder & bit register?

Newbie here, our professor had given us a big problem (i mean homework) on how to interface multiple SPIs using 1 microcontroller. But his requirements are quite exaggerated: 1 microcontroller ...
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1answer
299 views

Setting the address of MCP23017 IO Expander when using Multiple

I'm trying to use the MCP23017 I2C port extender which has 3 addressing pins to be externally biased to set the I2C device address. How should I connect the 3 addressing pins to select the I2C ...
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1answer
81 views

I/O pin driving PCB? Problem, Bug, Feature?

I built an PCB board housing a couple of ICs and the PCB communicates with a PC over USB with a Saxo board (contains FX2 USB controller and Cyclone FPGA). The Saxo board sits on my PCB as daugther ...
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2answers
81 views

What is a “current load” on a 24 V input used for?

The MAX14821 (datasheet) is a 24 V IO device that features selectable current loads for use in actuators on the inputs. What would this be used for? It's not just ...
0
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1answer
398 views

5V Tolerant I/O

A lot of micro-controllers has 5V Tolerant I/O pins using lower supply voltages (For example 3.3V). Even when they can't drive more than 3.3V at the output, they can be used in open-drain ...
2
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1answer
581 views

I/O input leakage current definition

I'm collected some input leakage information for I/O libraries. Most vendors and datasheets give a maximum value +/-1uA for the input leakage information (see below an example): This value is higher ...
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2answers
102 views

Signals shorted when connected to the input of an unpowered IC

I use one SPI bus from CPU to two FPGAs with different (i.e. individual) CS signals. The CPU and first FPGA are powered up, and the second FPGA is unpowered. When I send SPI signals to both FPGAs, ...
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1answer
77 views

8051 I/O programming logic/ how it works

I'm new to microprocessors and trying to figure out how they work. I am quite confused about using the ports as inputs and outputs. It says that we should send '1' to the pin if we want to use it as ...
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2answers
296 views

Theoretical max rate of input capture for a USB mouse and possible hardware limitations

I apologize in advance if this is not the correct forum for this question or if the question is too broad to answer. My background is in computer science and I work mostly in Java middleware so this ...
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2answers
255 views

Looking to bring 24V inputs to PC to store in database

I've been given a project that sort of bridges the electrical/PLC and PC/software world. I have to take a 24VDC photoeye and 24VDC encoder (1/4" to 1/2" pulse @ 540FPM ~ 1 pulse every 2.3ms-4.6ms) ...
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1answer
103 views

Protecting circuit from railway's high voltage

I am designing a control system which is going to be installed near a functioning railway. The system has many interfaces that are externally connected to different devices, it has Wiegand, RS485, ...
2
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1answer
2k views

Esp8266 nodemcu v3 connection to usb fingerprint scanner

My project is about making an ioT biometric attendance management using Esp8266 nodemcu and a Morpho usb biometric scanner. So my question is whether is it possible to connect a usb fingerprint ...
0
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1answer
94 views

AT89S52 switched mode IO Pin 2 not setting to ground

I am designing a simple circuit with AT89S52 micro controller. I set the I/O pins as high and when the switch is pressed will get connected to ground. And in my program I check for I/O pins as 0 and ...
1
vote
1answer
313 views

Can I use an analog input for a discrete signal field device on the A-B Micro820?

I have an Allen Bradley Micro820 (2080-LC20-20QWB) with four sinking 24 VDC analogue inputs and eight 24 VDC sink/source discrete inputs. I need one more discrete input for my project than the 8 that ...
0
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1answer
275 views

Can I use MOSI, MISO, SCK pings for reading input in AT89S52?

I am doing a custom keyboard for my project. It has totally 22 keys. I am using AT89S52 microcontroller. I have allocated P0.0 TO P0.7 AND P2.0 TO P2.7 AND P1.2, P1.3, P1.4 (totally 19 pins) which ...
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2answers
264 views

Trying to find out the voltage threshold for input of a GPIO pin in an FPGA development board

I need to use a camera module along with De1-SoC development board. Camera requires 3.3V to work and it provides outputs with a 2.5V output pin. I am trying to find what is the range of voltages that ...
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2answers
108 views

What is the purpose of RC in series on FPGA output pin?

Does the RC branch connected to the output as shown serve as a low pass filter? Shouldn't the output be tapped after the 50 Ohm resistor if it were to be used as a filter?
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2answers
2k views

Pin as both input (for a switch) and output (for LED) with ATmega32U4?

There are several questions close to this topic already, but they are either for another µC family, or target reading analog voltages or other special cases. So here goes: I would like to read a ...
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1answer
510 views

hookup a scope to monitor serial i/o

First off, I searched for this question and while I found other similar questions, none had an answer for this. I've got a serial cable from a (Linux) PC supplying data to a PCB (AVR XMEGA). I'm ...
2
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1answer
228 views

How does the Intel 8086/88 know when to assert the IO/M signal?

Consider an Intel 8088 processor with a standard, parallel RAM and ROM implementation that also supports address/data bus access to various external peripherals like analog-to-digital converters (ADCs)...
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0answers
249 views

Voltage Drop on I/O Pin of AVR Tiny Micro-controller

I am working on a project based on AVR Tiny85 Microcontroller interfacing with an RGB LED. In order to test the Tiny Board I/O pins I have written a sample test code to toggle I/O. Test Code ...
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2answers
384 views

How to extends Arduino Mega to 250 I/O pin

the title actually quite sums up my question, How to extends Arduino Mega to 250 I/O pin ? I will use it to drive 250 12 V relays (if a direct ic/chip that are 12V capable (max 50 mA per pin will be ...
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2answers
555 views

Designing a open drain LED driver

Will this open drain LED driver circuit work ? The open drain IO is governed by the following equation 0.5 <= V_LED_OUT <= 3.6 V (abs_max) V_LED_OUT is the voltage from open drain IO pin to ...
0
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1answer
48 views

ATmega32A _delay_ms after IO calls

I am loading the following code into ATmega32A PU 1535 to flash the LED on pin 40, PORTA 0: ...
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1answer
122 views

IO pin for iCE40 Ultra [closed]

What is the maximum IO pin current (for regular pins, not for LED pins) for iCE40 Ultra FPGA?
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5answers
898 views

Drive multiple LEDs ON together using PIC Microcontroller

I am using a PIC18F2420 microcontroller (I can change if required). The task is to drive up to 20 Power level indicator LEDs along with a few other LED indicator & switches using PIC. I can ...
2
votes
2answers
286 views

PIC24FJ128GA202 some I/O PortB pins not behaving correctly

I am working on a small project using a PIC24FJ128GA202, and noticed that my UART wasn't working with every RP pins. I ran the following code : ...
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3answers
265 views

Programmed IO vs interrupt for devices

Although I can understand the difference between programmed IO (PIO) and interrupt (INT) transfers, still there is something vague. In PIO, the processor repeatedly checks READY pin to see if the ...
3
votes
2answers
728 views

Can not keep pin LOW during FPGA configuration

I would like to have a control signal that stays low all the time and goes hi only when I tell it to. Initializing the pin in the entity does not seem to set the value to zero (xc6slx25-3ftg256): <...
5
votes
3answers
701 views

Multiple switches, same function. Can they be wired in parallel to a single I/O pin?

I'm working on a Raspberry Pi project that requires 30 separate momentary switches to be hooked up to trigger the same function within the software. It's for an art project. I don't need to ...
3
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2answers
4k views

help me to understand ANSEL register in PIC

in new to PIC,this is bit confusing. For switch ,usart we should clear ANSEL regsiter to make as digital IO so then only we can read 0 or 1 from that pin?, data sheet says if we set particular pin ...
2
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3answers
184 views

SPI interfaces on microcontrollers

My question is for microcontrollers in general. Can SPI be implemented with any 3 different I/O pins granted one is a clock signal? Is there anything special with certain pins that a datasheet ...
0
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4answers
895 views

How could I read a digital input (an open/closed switch) from a smartphone without a digitizing board?

I have to read a single digital input signal (a trivial open/closed-circuit push button) and use this signal in an Android application on a smartphone. Of course, I could connect a tiny Arduino-like ...
0
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1answer
155 views

design for a PC/104 interface bus expansion

Can someone tell my why this won't work or tell me a better way to do it? I have a TS-5500 from Technologic Systems that has a PC/104 bus which I am building a card to expand the IO ports. Pin B19 on ...
0
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1answer
611 views

In 8085, what is peripheral mapped I/O?

Is the peripheral mapped I/O different from what is known as port-mapped I/O or simply known as I/O mapped I/O? I don't see the usage of the term "peripheral mapped I/O" around much. Was it only ...
3
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5answers
2k views

Microcontrollers: What to do with unused non-IO pins?

There's plenty of information on what to do with unused IO-pins on a microcontroller. You can set them to a floating output, ground them, or pull them up to Vcc or down to ground. However I can't find ...
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3answers
108 views

Datasheet hunting -

I'm having difficulty trying to figure out voltage outputs for FPGAs. Let's use the Xilinx XC3S2000 FG900 as an example, and say I'm trying to figure out the voltage for pin T22. I do a search for the ...
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3answers
935 views

Use one or two transistors to switch an LED from PIC

I'm fairly new to electronics - I've had a reasonable amount of success with getting PCBs made using Eagle, but it was mostly wiring together breakouts and fairly simple stuff. I've spend the last two ...
1
vote
2answers
56 views

What is the max amps for the Adam 6050 module

I recently purchased an Adam 6050 module and need to power it up. However the manual seems a little vague, other than mentioning that it has a 10-30 volt unregulated power range. And that it ...
0
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3answers
1k views

How does open drain io act as bidirectional

Could someone explain how open drain io acts as bidirectional. Whether it is actually bidirectional or it can act only as input or output at a time.
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4answers
253 views

Easiest way to read a large bank of LED's

I have a pretty straight forward question but every answer I come up with seems over complicated or just plain wrong. I'm designing a data logger/fault detection system to be used for a large piece ...
0
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1answer
1k views

Arduino controlled boost converter

If I was to build a 12->65V boost converter using Texas's LM5002 regulator IC, would it be possible to tie an Arduino I/O pin directly to the EN pin to enable/disable the output, while keeping the 12V ...
2
votes
1answer
392 views

Will negative ESD strike pose any damages to I/O port connected to TVS?

I understand that bidirectional TVS can withstand both positive and negative ESD strikes, with the positive ESD current is shunted to Ground through TVS whereas negative ESD current is shunted to I/O ...
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2answers
98 views

switch that closes when power is on

I'm currently working on a project that makes a device "IoT-ready". So im looking for a switch, which got two inputs and two outputs. When I close the circuit on the one side, it should close it on ...
2
votes
5answers
863 views

Best way to get 256 io pins?

I'm connecting to an arduino or raspberry pi and would like to have 256 io pins. I found a 16bit io expander which has 8 unique addresses for 128 but that's the max I can do on i2c. Any other thoughts ...