Questions tagged [timer]

Circuit to generate a signal a specific time after a trigger event. The timing can be defined by an RC time constant, or by clock pulses from an oscillator.

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1answer
101 views

Real time clock MCP7940N I2C interface

The RTC MCP7940N is used in the system. The microcontroller and RTC MCP7940N are connected through the I2C interface. I would to know what is the better design to read the timer value from the RTC. ...
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208 views

STM32L1 Discovery Kit 5MHz PWM Generation

I have been using the STM32L1 Discovery Kit with the STM32L152RCT6 MCU. A project that I am working on requires me to output two PWM signals. One of these is a 100KHz square wave and the other is ...
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1answer
115 views

Is there anything wrong with this particular timer circuit utilizing 555?

I created following simple timer circuit for one shot operation. My expectation is it to give 5v as output (for D RELAY and SP RELAY) for certain number of seconds/minutes soon as it got powered-on. ...
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1answer
2k views

What does ClockDivision do, as opposed to the Prescaler for STM32 timers?

I am using an STM32 board (F7 series), and am looking through the HAL API documentation. When I initialize a timer, I see two values, Prescaler and ...
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558 views

555 timer circuit with d type flip-flop

Found this circuit for a 555 timer. I can't understand the use of the d-type flip-flop. Please explain.. And is the variable resistor used to adjust the frequency?
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174 views

What is incorrect with my 555 LED flasher circuit?

I have built a circuit to flash an LED using a 555 timer IC, but it doesn't flash... the LED just stays on steadily. -- I carefully followed the instructions on a common tutorial, which is: http://...
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1answer
56 views

How To Make A motor timer with Solar Panel [closed]

I need to figure out how to make a 763RLN, 667RN Nutone Fan Motor rotate twice a day. The motor is powered via a TOOGOO(R) 1.5W 12V Mini Solar Panel. The idea is that we have a EXP1250 12V 5Ah Home ...
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1answer
192 views

Precise low power millisecond timer

Any suggestions on a low-power programmable timer that does something like the following (to wake up a microcontroller)?: Shortest delay I need is about 10ms. Highest delay I would like is a few ...
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1answer
717 views

How to get a Timer started without interrupt?

I use an STM32F103c8t6. What I want is to measure time between several statements. I found out HAL_getTick does not work since the resolution is too small (1 ms). However, I cannot seem to initialize ...
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1answer
151 views

Errors in microcontroller delay routine

I have an issue with a delay routine that I am writing for use on a PIC32, the PIC32MX664F128H in particular. I have two separate delay functions, which use the same lower-level delay routine: one ...
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1answer
164 views

how can i add more leds to police light circuit?

This project uses a 555 timer and a 4017 decade to produce the flash police lights. This circuit has only 4 leds , 2 blue and 2 red. I want to connect in 16 leds ( 8 blue and 8 red ) is that ...
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1answer
74 views

Counting slow to fast in a microcontroller.(Ramp)

I want to make an increment(++) to a variable initially slowly then speed up linearly. For example, using a timer interrupt(every 1 sec) in increase the variable x by 1.so at first variable get ...
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1answer
356 views

Stm32F103 DMA TIM1 - Load 50% of period.

I wrote a code using DMA with TIM1. In DMA buffer i load diffrent periods and send to ARR Register. How Can I change a Pulse of PWM to 50% from Dma buffer ? ...
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1answer
4k views

How to dynamically adjust a timer with STM32

I've got this timer (TIM4) that's in PWM mode. I'm outputting one PWM channel and i want to wait a bit, and then grab the latest ADC samples from a DMA conversion. TIM4 -> ARR is 4096 TIM4 -> CCR1 ...
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2answers
138 views

Synchronize Clocks

I need to develop a system where there are 4 sensor boxes powered by USB and they have their internal clock. Each of these boxes are connected to a Linux pc and all these PCs are linked with WiFi. API ...
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1answer
127 views

LM555 timers for control of a secure door

I will explain existing hardware followed by my desired operation thereof. I have a security door the controller of which has failed. The door has four electronic deadbolts. -- A) Two open ...
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1answer
57 views

Simple residential blower control

Basic question is: Is it permissable / safe to connect a $10 plug in timer relay with potential for backfeed from a second source? 20 watt fan being switched. This is a SIMPLE question, compared to ...
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1answer
80 views

Analog dinosaur needs simple buzzer when timed power source ceases

OK, as my profile states, my electronics knowledge is extremely limited and so is my use of correct terminology and symbology considering I come from a mechanical background. I'm adding liquid ...
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3answers
1k views

On— off— on— off timer circuit

I want to make a circuit to do something that is relatively simple but I need to find the optimal way to do it in order to take as little current as possible. Here is what I want to do: When a ...
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1answer
633 views

Making 100 microseconds delay for STM32L0

I need to create 100 microseconds delay for STM32L0 using HAL. I have HSE 12 MHz. APB1 timer clocks 12MHz. ...
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1answer
78 views

Adding Transistor to Maintain Voltage Across Proprietary Switch

So, I purchased a camera trigger that moves the camera and then triggers the shutter. I wanted to change when the camera shutter was triggered so I purchased a cheap eBay delay timer relay. I knew the ...
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2answers
334 views

STM32F7 46 G Discovery setting TIM2 to 1 second

I'm learning to programm on an STM32F7 46 G Discovery board using Eclipse as an IDE and STM32CubeMX. I'm trying to set a timer (currently TIM2) to one second without using an ISR. I'd like to get a ...
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2answers
174 views

Low power delayed off circuit

I am running into problems creating a circuit that once a button is pressed ( clicked ) will latch and run for a few seconds and then turn it self off. This would be trivial with a MCU but now I am ...
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2answers
735 views

Powering micro controller using n-channel mosfet and tpl5111

I am trying to create home made battery saver circuit to powering on my microcontroller (nodemcu v2), I am following http://www.ti.com/product/TPL5111/datasheet/detailed_description, and created the ...
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1answer
769 views

20Khz 50% duty cycle PWM generation Problem in atmega 328p

I wanted to create a PWM of 20Khz with 50 percent duty cycle(can be varied within while loop) in timer 0 of atmega 328p with MOODE 7:fast PWM mode with top value as OCROA.I used OCROA register to make ...
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193 views

Transistor for 38kHz IR pulse amplification

I am trying to build a timer circuit in which I will send a modulated 38kHz (almost) signal to an IR Receiver (TSOP38238 in Arduino Nano) and I want to amplify the square wave to the IR Led to ...
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207 views

Problems with ICP Atmega328p

I am trying to use ICP (Input Capture Pin) functionality of ATMEGA328p (Arduino Uno board) and somehow it does not seem to work. I have connected a switch to ICP pin PB0 in this case, and want to ...
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1answer
44 views

Timer with fixed input [duplicate]

I'm using a lm555 IC in monostable mode. When my input varies from 5v to 0v the output goes from 0v to 5v. But this only happens perfectly if it happens just a pulse at the entrance, in case my input ...
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1answer
58 views

Problems with dividing a clock with 2 command bits

I am trying to make a clock divider commanded by 2 bits :DTPS. For instance if DTPS is: "00" we get the clock as output(2^0) "01" we divide the clock by 2 (2^1) "10" we divide the clock by 4 (2^2) "...
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1answer
85 views

Timer circuit activated by the ignition of a car

I need to create a timer system with the following characteristics: The system receives a post-key input signal (12v) from the ignition of a car. When this input ...
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1answer
93 views

Is this machine code insufficient to chip timing?

I'm having trouble performing basic communication between two IC's. and AT89S52 and an AT89C4051. Both are connected using 6 GPIO pins of which 4 of them on each microcontroller are high nibbles of ...
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3answers
539 views

Discrete one-shot lamp timer circuit

I'd like to use a momentary switch with a simple circuit (like the one below), that will illuminate two lamps for a short period (i.e. 10-20 seconds) with a single push. Obviously 555 timers are ...
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1answer
1k views

How to set two timers running at the same time in atmega328p?

I want to set up two timers running two ISR-s with different resolutions. One timer for counting milliseconds for clock time, another for counting microseconds when ...
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1answer
391 views

How to use two timers for one interrupt vector on avr?

I want to use timer1 and timer2 for same vector TIMER#_COMPA_vect isr on atmega328p. Idea is to start and stop one when requested, for time sensitive functions. And ...
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1answer
74 views

assembly timer code [ C8051F340 ] explanation [closed]

Hi my problem is that I cant understand this code when I test it on my microcontroller Si Lab [ C8051F340 ]and let it run step by step My problem is basically is when I test the program on my ...
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1answer
79 views

Delaying a logic level by some ms

I have a sub-module in a design that has it's own regulator, i want to use its enable pin driven by an MCU output to also toggle some other IC, say 10ms after the EN has transitioned. I know i can ...
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1answer
65 views

How to keep voltage at 0 or high resistance during circuit warm-up?

This is a timing question. I have this motion-detector: http://www.mpja.com/download/31227sc.pdf It says "Sensor module is powered up after a minute, in this initialization time intervals during this ...
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1answer
57 views

Design Timer circuit

Hi Am looking for to design timer circuit for run Exhaust fan My requirement is three phase 1 HP motor, 440 V ac, 50 Hz supply On time ; 4 Min Off time: 1 min so i need this cycle continuously. meant ...
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1answer
475 views

Can you measure the frequency via interrupts when the pins are used by an encoder? SMT32F4

In order to calculate the current speed, one option is to read the current position every 20ms. The average speed is position_old minus position_current. This works well if there are many pulses per ...
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45 views

Random timer windows on a DC circuit

Are there any components/devices out there (available via RadioShack, or some other vendor) that behave as follows (or similarly): When a signal/voltage is detected, a random (and preferably ...
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2answers
626 views

What is the simplest possible monostable 555 timer circuit?

Say for instance, the goal is to light an incandescent bulb for x amount of seconds (let's say 20). What is the simplest configuration possible? Of course, simple timer circuits aren't rare, and can ...
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1answer
127 views

STM32F4 OC Clock Jitter Problem [duplicate]

I am using STM32CubeMX to configure an STM32F4 to output a clock signal using Timer 3, Channel 4 on PC9. I have read in the datasheet PLL section that jitter shouldn't be more than 15ps RMS but I am ...
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4answers
4k views

Why are 555 timers so prevalent? [closed]

I've noticed is that 555 ICs seem to be extremely common. Why is the 555 so prevalent, or ubiquitous; what about it so useful?
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1answer
248 views

Can I use a 555 to ignore short DC pulses in simple switch circuit? Not same as usual debouncing [duplicate]

I have a reversing camera in my car that I wish to: switch on whenever the reverse lights come on turn off when reverse lights go off. Problem is, my car's computer will periodically send these ...
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0answers
208 views

STM32F4 OC Clock Jitter

I am using STM32CubeMX to configure an STM32F4 to output a clock signal using Timer 3, Channel 4 on PC9. I have read in the datasheet PLL section that jitter shouldn't be more than 15ps RMS but I am ...
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2answers
39 views

Simple circuit or component for output specific voltage in specific interval

I am a newbie to electronics and trying to learn some basics. Is there is any simple circuit or component which can output 5 V in every specific interval (10 sec). Just output and turn back off. I am ...
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1answer
159 views

building a random timer circuit that will delay from 0 to 3 sec after trigger input relay output

need some help to build a random timer circuit that will delay from 0 to 3 sec after trigger input relay output Have looked at a number of 555 circuits but no monostable or astable ic seems capable
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2answers
249 views

Hi Can we have delay timer with one Shot ON/OFF?

Need a Timer circuit like, for 20 sec it should be on then completely off. generally RC timer gets off gradually so the buzzer sounds for long. Thanks in Advance.
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2answers
345 views

Timer of 12 seconds using hardware circuit

In my design, say there are 2 pins A and B. Now I want to implement circuit in such a way that B is initially high , but when A goes low, after 12 seconds B will go low for short duration and again ...
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3answers
780 views

Timer to provide a short pulse after a power-up delay

I've been searching for a long time for a timer circuit that activates a relay for a short time(less than 1 sec.) after a few seconds(5 to 10 sec) when the current is switched on. There are many ...