Questions tagged [reset]

The reset line on a computer or other digital circuit places the circuit in a well defined initial state. Most microcontrollers have a built-in power-up reset to start the CPU executing code and may also have external resets and watchdog timers to help recover from unexpected events.

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ATMEGA328P reset circuit, not pulling down fully

Attached is the schematic of a reset circuit. When I press the reset button, the voltage on the reset pin is 2.5 V. Rmoving R13 naturally solves the issue, but I'm unclear as to why the ...
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1 vote
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Not able to flash MCU because of external watchdog

I am using the TPS3813K33MDBVREP watchdog on a PCB with a STM32 MCU. It is connected like the example in the datasheet. I can't program the MCU with a debug cable because the MCU gets reset from the ...
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How would I externally drive the Reset signal alongside a classic Power-On Reset circuit?

Say I have a D Flip Flop and I have a resistor, capacitor, diode, and Schmitt buffer to keep its reset line low for a few ms during startup (as per this answer) This takes care of power-on, but during ...
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2 answers
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Disable NE555 using an external microcontroller

I am trying to hack this board (it's a 60A PWM motor speed controller): Specifically, I need to enable/disable the 555 timer in the center using an Arduino. To accomplish that, it would be sufficient ...
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-2 votes
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Controlling the RESET in this IC

I'm using this - Ethernet Switch IC - KSZ9897S This is its Hardware Checklist. On page 193 of the datasheet, they have provided the guidelines on how to connect a signal to the RESET pin. My question ...
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Can a reset level from a voltage supervisor be controlled for power-on transitions?

This question is related to another circuit about I have talked in an previous post. But I think by the nature of the question, this must be treated apart, in a new post. I need to keep a signal from ...
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-1 votes
1 answer
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How to add custom chip enable (reset) signal to chip?

I use in my schema I2C chip that not have pin for hardware reset of chip. You just have power pins VCC, GND or signal pins. I would like to add trigger switch which reset (shortly break power to chip) ...
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2 answers
71 views

How to calculate the pull down resistor value for an input pin in a 74HC273 flip flop?

An old circuit I'm checking was built using a philips 74HC273 (CMOS dev) datasheet in a card that is receiving reset and other signals from another card. In that other card, reset signal comes from a ...
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3 votes
1 answer
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Question about Stm32 "Blue Pill" NRST pin schematic

I have a question about the schematic design of the STM32 "Blue Pill" board. In the datasheet it says there is an internal pull-up resistor of ~40k is included in the MCU for the NRST pin ...
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  • 119
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1 answer
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Is there a tool or method to list signals that have no reset in the HDL design for an FPGA?

I have to reuse an old VHDL draft design which was not fully verified and validated. The code is huge - it takes around 30k slices to be implemented on an FPGA. I see that some signals are forgotten ...
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1 vote
1 answer
58 views

Timing Async Reset with Sync Deassert

I've been reading about FPGA resets, particularly the links in benefits of removing reset in an FPGA design and the article http://www.sunburst-design.com/papers/CummingsSNUG2002SJ_Resets.pdf. For my ...
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esp8266 occasional resets when controlled relay is energized

I am having trouble with a circuit that I have designed for an esp8266, that controls 4 relays. The MCU is flashed with esphome, and occasionally resets itself, after turning on one of the relays. I ...
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96 views

Assert and de-assert in reset

I'm reading linux reset controller driver codes and found assert and deassert: ...
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15 votes
3 answers
568 views

Why specify a maximum pulse width for reset pin?

A colleague and I are working with the Analog Devices AD74413R ADC for 4-20 mA current loop communications. On pages 15 and 16 of the datasheet, timing characteristics are presented. We encountered an ...
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1 answer
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What is meant by "monotonic reset"?

Can someone tell me what does it mean by Monotonic Reset? I read this below paragraph from this document and got this doubt. A reset generator / voltage monitor is one option to provide a proper ...
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2 answers
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Working of this Circuit - Reset

I'm using this Ethernet transceiver PHY to study the working of the RGMII interface. Can someone explain the working of figure 18 on page 75? What is the purpose of D1 and D2 along with the RC? How ...
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0 votes
1 answer
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Is an RST pin the same as a microcontroller NRST pin?

I am currently working on a PCB design using a STM32F411CEU6 microcontroller. In order to debug the circuit using an ST-Link, I have placed a header in order to access the pins in the microcontroller. ...
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1 vote
0 answers
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AVR self-reset / hardware reset from own own pin

Can I use a capacitor to perform a self-reset / hardware reset of an AVR microcontroller? The capacitor would be driven low by a pin on the microcontroller. Arduino uses this mechanism for programming ...
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2 answers
120 views

AVR reset pin capacitor causes chip to enter bootloader on powerup

I have a circuit using an ATmega32U4 and am using the Arduino Leonardo/Micro Caterina bootloader (the one that comes with arduinoIDE v1.8.13). The problem I am having is on power-up (via USB ...
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2 votes
2 answers
325 views

Single chip power good IC?

It seems like there should be a million chips for this, but for the life of me can't find any. I'm looking for a small (SOT23 or similar size if possible) IC that provides an active high when the ...
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1 vote
1 answer
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vhdl reset synchronizer [duplicate]

I have a question regarding reset synchronizing. If I have a reset_synchronizer.vhd file like this: ...
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0 votes
3 answers
87 views

How can a momentary switch be wired to only work after being held X seconds?

I have a few electronics projects in progress and would like to include a switch to reset by providing a short disconnect from power (be it from the wall or a battery) and on boot copy the original ...
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1 vote
1 answer
48 views

Reset when battery powered device receives USB power

Device (microcontroller) is powered by battery or USB, through load sharing circuit. When no USB, operates on battery. When USB applied, USB powered. I want device to reset once when USB power ...
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0 votes
1 answer
218 views

Serial DTR reset on custom Arduino-based board not working properly

I have a custom atMega328 board that's essentially an Arduino Nano with a few circuits doing some custom interfacing. Nothing super crazy. However I'm running into an issue with the RESET line, which ...
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1 vote
1 answer
388 views

Why is this power-on reset generator Verilog module getting optimized out?

I am trying to write a Verilog module that generates a power-on reset signal for a few clock cycles. I am synthesizing using Lattice iCEcube2 + Synplify Pro targeting an iCE40 HX1K on the Nandland Go ...
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0 votes
1 answer
84 views

What function does this resistor/capacitor arrangement provide in this reset circuitry

I have been trying to decipher what the arrangement of the resistor and capacitor does in the circuit below, but I am at a loss to explain it. Can someone explain to me what it is doing? The circuit ...
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3 votes
2 answers
146 views

The function setup () executes after ATmega328P wake up from the sleep mode

I am using ATmega328P in deep-sleep mode in Arduino IDE. For wake up I am using PCINT. I can see it is working but setup () also executes after wakeup. Is it ...
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1 vote
0 answers
342 views

STM32F103C8T6 Bluepill - core held in reset error

"Core is held in reset" - the error stm32 st-link utility tool throws when I try to erase my STM32F1 blue chip. Is my board damaged or something? In Settings Window - Under STM32 Target ...
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0 votes
0 answers
158 views

HAL_Delay fails after flashing code

My code runs differently if reset vs. power-cycle. My board has a status LED. My program flashes an LED on and off. When I flash my code via my STLink V2 and hit my reset button, the light turns on, ...
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0 votes
1 answer
102 views

MAX7221 always hangs on first power on

I have an issue quite similar to this one. The behavior of my MAX7221 is the following: when powering on the board the first time (let's from cold & dark) it turn on all the segments and does not ...
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0 votes
1 answer
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JK Flip-Flop 0-9 up/down counter [closed]

I designed a 4-bit JK up/down counter. I want the circuit to be reset to 0 when counting up when it reaches 9, and to be reset to 9 when counting down when it reaches 0. Anyone know how ? I tried a ...
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0 votes
1 answer
90 views

Help wiring a pic processor to a FTD chip

I have been trying to wire a PIC18f4620 to a FTD1232 using the MLCR reset. Below is my circuit. When I hit the reset, the short causes the processor and the FTD to lose power and I am unable to ...
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2 votes
1 answer
657 views

SDC Constraint for reset synchronizer

I have a reset bridge in VHDL which is based on a multi-FF synchronizer chain as depicted below. This reset bridge is used in various instances throughout my design. I want to properly constrain the ...
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0 votes
3 answers
185 views

Arduino spuriously resets with power draw

I have a simple circuit, pictured below, that uses an Arduino to control two large bidirectional motors via 12V relays. Normally this works a treat, but sometimes the Arduino ends up resetting itself. ...
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3 votes
4 answers
221 views

Why is NMI commonly pulled high on many ARM SoC schematics?

I've noticed that "AP-NMI" is pulled high on several ARM SoC schematics, and it is pulled high by the real-time clock (RTC) voltage, which is an always-on power domain (battery backup). Why ...
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0 votes
1 answer
308 views

Arduino UNO-CH341 keeps resetting randomly

A brief summary: I work at a small workshop/factory, and we've got a single three-phase compressor for the whole factory, a week ago the compressor controller flat-out died and that left the entire ...
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1 vote
1 answer
294 views

How do I build and simulate a T Flip-Flop without a reset in SystemVerilog?

I found that I could not get a T Flip-Flop without a reset to simulate in SystemVerilog, but I could get a JK Flip-Flop without a reset to simulate. This is because I can set a JK Flip-Flop to a known ...
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0 votes
2 answers
102 views

Is it ok to connect a CMOS logic output to a power-on-reset circuit like this?

I am trying to make a power-on reset circuit that can also be manually reset. The reset is active-low. When the capacitor is charging, I'm assuming 5v will be present on pin 10. Would this damage the ...
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0 votes
3 answers
2k views

JK Flip-Flop Counter: How to reset a counter?

I currently have a 3-bit asyncronous counter (built using J-K flip flops) that continuously counts up. However, I am struggling to figure out how to reset the counter to 0 when an input (Reset) is ...
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  • 113
0 votes
1 answer
71 views

74HC73 reset on released button

I want to use one button for set and reset. With a hex-inverter (because of falling edge), when I press the button, set works fine, but I need another button to reset the 74HC73. Is there some ...
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4 answers
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posedge clk vs posedge clk, posedge reset

I'm looking for the difference between: always_ff @(posedge clk) begin and: always_ff @(posedge clk, posedge rst) begin Here's ...
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1 answer
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Could power cycling a modem 24 times a day for over 3 years (>30,000 times) cause the modem to lose its settings? [closed]

Could power cycling a modem 24 times a day with it being on for 10mins at a time for over 3 years (>30,000 times) cause the modem to lose its setting and revert to factory? This modem.
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1 vote
1 answer
134 views

In SR latch when apply a pulse to reset latch how the Q is changed?

Here is the initial state of SR latch both reset and set inputs are zero. Here we apply a pulse to the reset input and it shows it changes in this way first - and then - The thing that I don't ...
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1 answer
81 views

Controlling AVR reset via voltage divider

I have an AVR atmega32u4 which is being run on 3.3v. I program it using a avr usbisp, which runs at 5v.. The problem i'm having is driving the reset pin.. I currently have this schematic where ...
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0 answers
39 views

Cold Reset STC125A60S2 PLC Board

I am working on these PLC Board: http://more-suns.com/product/html/?321.html but I cannot contact manufacturer. The fact is to have it programmed I have realized that I can only do it after a cold ...
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0 votes
1 answer
123 views

Thunderstorm reseting my micro-controller

I think this is a follow up from my previous question. If not then please ignore it. I have created a very basic (crude) alarm system that uses a reed switch. Luckily there was a thunderstorm and some ...
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1 vote
3 answers
337 views

Working of the "Capacitor Reset" block

I am reading this App Note. On page 6, Figure 5, they have provided a circuit which helps with the soft start and input protection circuitry. I am not able to understand the "Capacitor Reset&...
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1 vote
0 answers
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Atmega328p-pu (arduino bootloader) processor freezes/resets randomly

I have updated the schematic of my project. The board for this was produced and all components are soldered to the board. Now I am trying to make a "n20 gear motor" move using the motor ...
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0 votes
1 answer
141 views

NRST Pin pull-up resistor on STM32F303RET6

The datasheet from the STM32F303RET6 shows that a pull-up resistor (a weak one?) is already included in the device itself. Rpu. But my knowledge tells me I have to add one myself in front of NRST, ...
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1 answer
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Noise that resets a device that I would like to avoid from chip reset pin

History/context: I talk about a 15Mhz noise when drill machine or any kind of machine activation in my network, before, at other post. By the moment neither RC, RL or RLC butterworth low pass filter ...
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