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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112 views

Why is there a 100nF capacitor in the Arduino Severino reset line?

While looking at the Arduino Severino (Single-Sided Serial Board V3) schematics I notice it has a ceramic 100nF capacitor in the reset line (marked in red in the picture below). My questions are: ...
3
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1answer
55 views

How to find cause of reset in PIC16F microcontroller?

I've worked with other microcontrollers that have a register that I can check on powerup to check a register that contains debugging information on the cause of the reset. Initial searching revealed ...
4
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3answers
193 views

|Solved| PIC16F628A Resetting after relay turned off

I am having problems with controlling a relay with load on it. I am using PIC16F628A. The problem is following: The relay has load. At first it is off. When the microcontroller's output is on, the ...
2
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1answer
50 views

difference between POR and other resets

everyone. I would like to ask you about the difference between Power On Reset[POR] and other Resets because in PIC18 controller datasheet i have seen a statement like: ...
2
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2answers
74 views

How to trigger reset at long press of button

I am trying to make a button control on/off and reset all in one, but I can't quite get my head around how to design it. It should basically function like a PC power button. If short press it's ...
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0answers
86 views

MSP430 GPIO behaviour on power off

I have a simple circuit which contains an MSP430 connected to a DAC8551. I'm using PORT1 so have implemented a bit-banging approach instead of using the USCI module (bad, I know). I've noticed a ...
2
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2answers
85 views

AVR Reset pin for a long time

I just have a little Question, if I drive a reset pin to low (reset active) of an Atmel AVR for a long time (1 week for example, in fact it'll be really variable depending on the use) can it cause ...
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3answers
114 views

External watchdog reset for AVR required

I had a circuit with ATmega644PA and use internal watchdog timer to bring the controller from a hang state to known by a reset. but my code still hangs in some loop ...
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4answers
151 views

Why does my AVR act weird (resets, data corruption) when receiving a few bytes on the UART?

I have an ATmega644 connected to another device using the UART. After receiving a few characters on the UART the device resets and/or acts weird. Some examples of this behavior: Code before the main ...
3
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3answers
96 views

Is there any problems or issues with holding !RESET low on ATMEL ATMEGA328P till rest of board self checks?

I'd like keep an ATMEL ATMega328P in reset for about 4 sec while the rest of the board self checks on startup. Is this OK? Are there any issues that would make holding the RESET low for this extended ...
3
votes
1answer
180 views

Flip flop with load/set, reset, clk, and input

I'm not looking for a hardware language description of the flip flop, but the logic gate level to implement. In verilog, the equivalent I'm looking for is ...
3
votes
1answer
58 views

Reset and clock

In digital circuits (combination & Sequential) which input holds more priority clock signal or a reset signal? suppose we give a input reset in an asynchronous counter then reset will wait for ...
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0answers
83 views

Relationship between reset pins and SWD functions (ARM Cortex M0)

On many microcontrollers or other devices without JTAG/SWD functionality, there is a reset pin which when low unconditionally and asynchronously forces everything into a known state. On devices with ...
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votes
2answers
157 views

What could cause unexplained brownout resets?

Context I'm building a 7kW bidirectional two-stage switching converter. Each stage has its own control board and processor. The entire system runs off a common 24V rail. Isolation stage Two ...
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votes
2answers
885 views

What could cause a microcontroller to unexpectedly reset?

One particularly irritating variety of bug in a microprocessor-controlled system is for the microprocessor to unexpectedly reset. An important tool for debugging this kind of problem is a list of ...
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2answers
134 views

AVR /RESET pin voltage

The two AVRs I'm using right now (ATmega1284P and ATtiny4313) are both powered by 4.96V. I'm measuring a voltage on their /RESET pins of 6.33 volts. Is that normal? Where is it coming from?
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1answer
157 views

what is logic contention when using a voltage supervisor?

I am using a voltage supervisor from MAXIAM (MAX6734A).I am confused about design notes in page 11. so,what is logic contention? the uP that I want to monitor is STM32F103ZET6.I read its ...
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1answer
729 views

Connecting the RESET pin of AT8051

How should I connect the RESET pin in a microcontroller (AT8051), and why in that particular way?
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2answers
97 views

Board occasionally resetting when dropped or knocked

I have a board that consists of Arduino pro mini (ATMega328P, ceramic resonator, tactile reset button) SD card I2C sensors LTC3525 boost converter (IC, inductor, caps) Very occasionally, if the ...
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2answers
962 views

Given a gated SR latch, How do I make it a set dominant gated SR latch?

Another weirdly worded question in my digital logic book. It doesn't specifically define set-dominant or reset-dominant - nor does it show how to use these in practice with drawing circuit diagrams. ...
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1answer
56 views

Is RST valid while programming with ISP?

First time designing a PCB board whith a MPC82G516AP (8051),I'm using an external Watchdog Timer chip。So is the watchdog reset valid while programming with ISP?
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1answer
89 views

Resetting a 74xx164 on power-up

I while a ago I saw a circuit in a datasheet that automatically cleared a 74xx164 shift register on power-up. I don't exactly remember which logic series it was (might have been LS or HC), and the ...
3
votes
2answers
454 views

Reset pin on ATtiny84/85/2313 clarification

I have two questions that I was hoping someone could clarify with a quick True/False. When using the ATtiny85/85/2313 the reset pin is connected to a 10k resistor which is connected to VCC. When ...
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2answers
220 views

Pullup or direct drive when handling active low inputs/resets?

Active-low reset inputs seem to be a holdover from TTL logic where the falling edge was faster than the rising edge, so the falling edge was decided as more important to increase the maximum possible ...
3
votes
3answers
357 views

Generate a reset signal from a falling edge trigger

I'm working on a microcontroller design where the mcu is placed in hibernation mode, and can only be awoken by a pulse(high-low-high) signal on the reset pin. (active low) As a wake-up source i'm ...
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votes
2answers
110 views

Electronic Reset SW

Normally, there is a mechanic button at the end of the RESET SW pins on the mainboard. Now, I like to create a way to electronically trigger the reset function of my mainboard from another computer. ...
3
votes
1answer
110 views

PICKIT 3 resets PIC16 three times upon reprogramming

I am using the PICKIT 3 with MPLAB X with the default setings. When I press F6 to build and run my code, I notice that the PIC16 resets three times: twice with ...
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3answers
156 views

Effective use of output signal of a watchdog timer

Subsequent to my previous question regarding watchdog timers, I am interested in deciding the RESULT of such a watchdog: Assume I add a generic external watchdog timer to my circuit. If not toggled ...
11
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2answers
4k views

What values of resistor and capacitor to use for AVR reset pin isolation?

Background... I'm a newbie to AVR applications. I recently built two ATTINY13-based circuits (glorified LED blinkers) which worked correctly (independently) on the breadboard. When I combined them on ...
3
votes
1answer
508 views

Using AVR reset pin as ADC

I am using an ATTINY13 for a toy application. It simply blinks LEDs in specific patterns. I decided to add a "speed control" using a potentiometer but the only pin I had left is the reset pin. I've ...
2
votes
1answer
1k views

STM32 NVIC interrupts after a reset / power-on

I have a few active-low signals that I want to interrupt on. During normal operation, the interrupts work just fine. However, on reset / power-on only rising edge is detected. In other words, on ...
6
votes
3answers
231 views

Using reset controllers with modern microcontrollers

Are reset controllers necessary for modern microcontrollers, such as the LPC2138 or 9S12XD256? Most ARM processors I have seen have their own brown-out detectors and reset properly, and I don't see ...
0
votes
1answer
528 views

Is RESET* on the XMEGA disabled when using the PDI interface?

When PDI CLK is connected on the XMEGA (also the RESET*) pin, can this pin still be used to trigger a reset on the chip? If so, how does the chip tell the difference between PDI being used as a clock ...
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2answers
728 views

Resetting XBee with an Arduino

I would like to be able to reset an XBee with an Arduino by connecting the reset pin on the XBee to a General I/O pin on the Arduino. I'm wondering if any additional components (transistors, resistors ...
3
votes
3answers
1k views

Atmega32 factory reset board

I want to know is there any reset board available ( I mean schematic, link, tutorial or anything else ) out there for Atmega32 microcontoller ( I heard about high voltage reset board, I found some ...
4
votes
2answers
473 views

Electrical reset to a SIM card

I have a SIM card reader connected to an ARM, and I'm trying to get the SIM to send an Answer To Reset (ATR) and to get the reader to capture it. As I understand, an ATR is sent after an "electrical ...
3
votes
2answers
6k views

STM32: Performing a software reset

I am trying to perform a software reset of my STM32F2. (Reference manual available here.) The relevant page of the reference manual (page 80) gives little information. Basically, the ...
4
votes
3answers
1k views

Do AVR registers and ports need to be initialized to zero?

During the initialization routine of my code I use to do such things as: clr r0 ; will always stay zero and: ...
0
votes
1answer
531 views

Hard resetting an STM32

My STM32 is behaving weirdly, to say the least. What is the best way to "hard reset" an STM32? I've tried pressing the "reset" button, and unplugging/replugging everything, but it seems like the ...
2
votes
4answers
565 views

What is the common pin configuration upon microcontroller reset?

I have looked through two datasheets and user manuals now for two different microcontrollers (LPC2387 and STM32F4xx), and I haven't found (probably missed) anywhere where the initial state of the GPIO ...
0
votes
1answer
2k views

Xbee Factory -Hardware reset without serial communication

I'm using "XBee 802.15.4 Module" After successful connection with X-cut & made a "+++" it responded "Ok" Then is stopped working .... I tried to reconnect to it again & failed .. it no ...
2
votes
2answers
128 views

Device is reset when switching power sources

I use a home weather station. It is powered by two AA batteries (2 x 1.5 = 3.0 V nominal). The problem is that it eats more than 1 mA and that is quite a lot of power and I must buy a new pair of AA ...
4
votes
4answers
623 views

How does a latch determine its initial state?

How does a latch get its initial state? I'm guessing that it depends on race conditions and which ever condition comes first then that is the state that the latch starts off with.
2
votes
2answers
719 views

Atmega328 reset pin not working after re-burning Arduino boot loader?

For a bit of background you might want to read atmega328 with optiboot not compatible with Arduino? But I will summarize anyway. I have some Atmega328 chips that shipped with the optiboot ...
2
votes
1answer
1k views

Can an ATTiny with RSTDISBL programmed be reprogrammed over ISP?

The ATTiny85 datasheet, on page 152, seems pretty clear on this: After this fuse has been programmed device can be programmed via high-voltage serial mode, only. But elsewhere, on page 28, it ...
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votes
5answers
2k views

Reset: synchronous vs asynchronous

I've been working with fpgas for years, and always used synchronous resets for every parts (that need it) of my circuits. It helps the circuit to be globally reset at a given clock cycle. However, I ...
3
votes
1answer
372 views

MSP430 Illegal Instruction

A few questions here along the same lines, I'm looking at the datasheet for the MSP430x2xx family (I'm using the MSP430F235 FWIW). It says there in section 2.2.4 that "illegal instruction fetch" is an ...
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2answers
77 views

Controller Resets after Enabling Cache

I am using a MCF5253 controller which is based on Coldfire Architecture. It has 8KB of Instruction Cache. Everything was working fine till I enabled it's Instruction Cache. Now what's happening is ...
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5answers
336 views

Does reset do the same thing as shutting off the power to this device and turning it back on?

I am trying to control a serial dataflash memory through an mbed. It is an AT45DB021B and the datasheet is here. It has a reset pin that I have wired to the mbed so that a software reset can be done. ...
3
votes
1answer
3k views

How does the Arduino Deumilanove Auto-Reset Function work?

I'd like to hear some explanations as to how the Arduino Duemilanove resets the ATMega328P over USB through the FTDI FT232R transceiver. I know it involves the IDE playing some games with the DTR ...