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.
Questions tagged [reset]
384 questions
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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 possible causes. What could cause a microcontroller…
Stephen Collings
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Necessity of an external watchdog timer
What is the need for an external watchdog timer for a microcontroller?
Most of the microcontrollers are designed with an internal watchdog timer. However, in some of the circuits they are using an external watchdog timer (such as PIC16F1824).
Photon001
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Reason for x86 reset vector being at 0xFFFFFFF0 instead of 0xFFFFFFFF
The top answer to this question on Super User gave an explanation that was satisfactory to me at first as to why the reset vector is not at address 0 (afterwards , I realized that it doesn't why the end of RAM couldn't be put at 0xFFFFFFFF and then…
Melab
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SRAM isn't blank on powerup, is this normal?
I had finally finished my Z80 memory board, but I was disappointed to see that it wasn't working properly (simple NOP test with the address lines connected to some LEDs) as the counter quickly spiraled out of control instead of incrementing as it…
KeatonB
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Should all traps always be defined?
I've seen two cases now with dsPIC 30F4013 where the controller was resetting due to an undefined trap. Why these traps were getting raised in the first place is still a mystery, but that's not my immediate question. I'm starting to think it would…
Stephen Collings
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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 SYSRESETREQ bit of the Application Interrupt and Reset Control…
Randomblue
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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 unexpected specification, a maximum duration for…
JYelton
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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 a solder perfboard with a shared power supply,…
JYelton
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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 was told that in ASIC circuits, people tend to use…
Aurelien Ribon
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Arduino resetting/hanging due to sparks in ac line
This is the PCB design of the project I have been working on recently (my first pcb design).
The idea is to control ac appliances (fans, bulbs etc) without relays. I am using triacs which are better than relays for such applications. I am using…
Whiskeyjack
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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 programming with an AVR 6 pin programmer does the…
ben
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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.
Lightyear Buzz
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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:
out PORTA, r0; initialize ports
out DDRA, r0
out PORTB, r0
...
Is this actually necessary? Or can I be sure this is…
Stefan Paul Noack
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Arduino reset with FTDI breakout question
How do you get the SparkFun FTDI Basic Breakout board to auto reset?
I still have to hit the reset button for any Arduino clones when I use the breakout board. I have tried connecting to the DTR pin and other methods of trial and error but I am just…
ArduinoFun
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"recommended that CLK begin toggling within 150 ms ... to ensure long-term reliability of the device" -- why?
In Intel's Pentium Processor Family Developer Manual, regarding the CPU clock, it says that "it is recommended that CLK begin toggling within 150 ms after VCC reaches its proper operating level. This recommendation is to ensure long-term reliability…
Zane Kaminski
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