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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2
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1answer
1k views

Timers and internal clock generator on Freescale MCU

I am using MC9S08AW60A with DEMO9S08AW60E Board (Freescale). I have studied about the timers given with the MCU. I wish to know how exactly to Implement timers by code. The Freescale suite also comes ...
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1answer
500 views

Arduino with multiple LEDs and timers

I'm working on creating a wireless interval timer with an Arduino, is there a specific Arduino board required that can work with multiple LEDs and give me the programming capability for providing time,...
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5k views

Need help understanding AVR ATMEGA / ATTINY timer mirrored output

I am trying to use Timer1 of Atmel AVR microcontroller, either AtMega328 as used in the Arduino, or the ATTiny85, to output two clock signals which are mirror images of each other. The frequency I am ...
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3answers
1k views

Use USB as an on-off switch

I'm looking for a way to build a zero(ish) cost intervalometer for my Canon SLR using only stuff that I have or can get very cheaply (my budget is about $4). I've already managed to "build" a wired ...
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2answers
201 views

Delay then off for tone signal

I have a simple circuit using a 555 timer as an oscillator to output a 12v tone to an intercom system. I'd like to make a delay circuit that will turn off the output of my circuit after a delay. ...
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3answers
4k views

shutting off power to circuit after a short time from an alarm clock

I am helping with a middle school project. The idea is to power a 3 V vibrating motor for about 10 seconds after the alarm goes off. The cheapest way so far I have found is to get a dual alarm clock ...
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2answers
3k views

Can't set to Fast PWM OCRA mode

Trying to have Fast PWM mode when TOP == ORCA. Works fine with OCA toggle (measuring correct frequency), but doesn't work in ...
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3answers
362 views

Ideal Hardware Timer Setup Routine

Imagine you were trying to write a C routine for an 8bit microcontroller that converted a desired timespan (be it seconds, milliseconds, hertz, etc). to the corresponding hardware timer preload value (...
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2answers
1k views

Method to determine least-error prescaler and top values for timer1 of Arduino?

If this question should be in StackExchange instead of here I can delete here and post there. Using an Arduino Duemilanove (Atmega328) I am trying to generate a square wave (50% duty cycle) of ...
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1answer
781 views

Fast PWM and Atmega1280 problem

Hello I have some problems to understand how to bind a Timer to a Pin and because of that my code isn't running... ...
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3answers
376 views

Example circuit of fading tone?

I'm looking for a simple circuit, preferably based on the 555 in order to get continuous configurable fading tones (chimes), just like a "door open warning". It will fade in and fade out, not very ...
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3answers
7k views

DIY small motor that turns for x seconds every y seconds

I'm a civil engineer, hiker, and hobby photographer. I am trying to build a little device that gently turns a small motor on every x seconds, keep it on for y seconds, and stop it for z seconds. For ...
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1answer
282 views

Drive relay when “key” is connected

I'm trying to design a circuit that will drive a relay (and thus turn on a bigger circuit) when the correct "key" circuit is connected. The "key" is contained within the hashed box and functions as I ...
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1answer
3k views

Which is better for the 555, a smaller capacitor or a larger one?

As I understand it, there are many ways to combine two resistors and a capacitor to give the same time characteristics in a astable 555 setup. My question is which is better, a larger capacitor or a ...
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6answers
2k views

Precise timing with a PIC18 microcontroller?

I'm trying to write a software serial implementation and am having trouble with timing. I'm using Timer0 on a PIC18F242 and for some reason it does not seem to be very accurate. I've been trying to ...
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1answer
131 views

Time delayed optionally postponable from a second input

I need functionality similar to that provided by true-off-delay relays, just a little different. I can't come up with a circuit. I have two inputs (A and B) that I want to control one output (C). ...
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3answers
2k views

Which of these approaches for a watchdog timer?

I recently learned about watchdog timers, and am trying to implement one for my circuit for the purpose of resetting my (AVR) microcontroller if it hangs (i.e., doesn't respond to the watchdog). ...
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1answer
2k views

Using Timer0 overflow to gate Timer1 on PIC12F1822

I am trying to use TMR1 to count TMR0 overflows. To do this I am using TMR1 with gate ...
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1answer
897 views

Generate a 200kHz varying voltage signal

I have a 12V DC supply from just a normal household converter. We have to make a circuit which will output an 200kHz AC signal with a p2p voltage of 3-12 volts depending on a strain gauge. 3 being no ...
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1answer
498 views

Using a diode or resistor, to supply minimal voltage to LED Driver (Help!)

I'm using a dual 60W LED multi-chip pendant lighting (a.k.a. "high bay" pendant light with two 60W LED chips). This light is using an RGB driver (one per multi-chip) that has a remote control to ...
4
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1answer
6k views

Using a 555 instead of 7555

Im creating this circuit and it requires a 7555 timer. A 7555 timer is like the next generation 555 since it is CMOS. Now there are no 7555s or CMOS 555 in my area and was wondering what will happen ...
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2answers
1k views

3 minute switch/timer

I have a portable mortor mixer that came with a on/off switch. My mixing time is consistantly 3 minutes long. I would like to know if it is possible to buy/make a toggle/rocker switch along with a ...
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2answers
3k views

Why does MSP430 have 2 capture signals for each capture/compare channel? Pin assignments recommendations?

Let's take MSP430G2553 as an example. If you look at the pinout in datasheet, you'll see: P2.1/TA1.1 P2.2/TA1.1 One could think that those TA signals identical and multiplexed twice as a courtesy to ...
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1answer
639 views

Power Off Delay circuit

I'm looking for a timer that starts when power is removed. Here is the use case: The head light on dirt bike my turns off with the engine. This good when it's parked. This is very bad when doing ...
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2answers
5k views

Is this StopWatch Accuracy correct? [closed]

This question would be easy for anyone who has some tech experience with stopwatchs. I'm going to make some measurements. and I need a 1ms accuracy stopwatch. I found one that could do the work with ...
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3answers
1k views

Sync video with data

When I have a datalogger and I want to sync a video-file to the recording, what would be an easy method? The logger and the camera both have an internal clock, but they may not be set exactly to the ...
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3answers
6k views

purpose of diode in this 555 timer application

I'm a newbie in electronics. I need to make a 555 timer base circuit(Refer to the schematic below) such that O/P pin of 555 is held LOW by default at power on, and the I/P pin is held initially at ...
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3answers
1k views

Countdown to specific date and time (6 months away) and then count up

I am looking to build a device that would countdown to a specific date and time (approx 6 months away); countdwon in days:hours:minutes:seconds. And when it reaches that date and time starts counting ...
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2answers
2k views

Why does 555 timer output change based on load?

I have a 555 timer setup in astable mode, with a frequency of about 1Hz which I measured and verified without load. Out of curiosity, I connected an 8 ohm speaker, expecting not to hear anything. ...
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3answers
4k views

Suggest a timer chip

I need to take voltage measurements separated by long delays (couple of hours) and beep a buzzer when voltage level is met. Power consumption is important. What I want is a simple timer chip like ...
4
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1answer
6k views

C18 Timer0 timing calculation using MCC18

I am programming a PIC18F4520 and I've set it to use a 32Mhz internal clock. I need a counter to tick every second so I'm using TMR0 for this purpose. To use <...
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2answers
7k views

High resolution timer on the BeagleBone?

Is there a high-resolution timer (microsecond resolution or better) available on the BeagleBone (TI AM3358 ARM Cortex-A8 based) development board?
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1answer
318 views

Is using a shorter timer period less accurate than using a longer one?

I'm using a dsPIC 33FJ128GP804 and I'm trying to record data at 200 Hz as accurately as possible. My device also has a GPS and I'm noticing that my timer is drifting compared to the GPS by about 333 ...
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5answers
7k views

Random time timer

I'm constructing a simple circuit that beeps a beeper on a given time interval, using a 555 timer. Is there any simple way to randomize the time on the 555 timer between two given intervals, say, any ...
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3answers
219 views

Substitute a button for a timed event?

Disclaimer: I am a total newbie I have something I bought that once is switched on does something each time I press a button, now, I want that to happen periodically(no accuracy needed) so I was ...
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2answers
6k views

How to configure the internal oscillator in a PIC16F616?

I want to use the internal oscillator in PIC16F616 in 8 MHz configuration and have the I/O function on RA4 and RA5. I've read ...
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1answer
10k views

What is the purpose resistors and capacitor in this 555 circuit?

What is the purpose of the capacitor , the resistor , and the variable resistor ? Do they work like clock pulses for the 555 timer?
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1answer
1k views

Timer1 not running on PIC16F628

I have this little project that requires exact clock so I'm using 32768 Hz quartz on RB6 & RB7 on my PIC16F628. Both pins are grounded using 33 pF capacitors. My code that configures the timer1 ...
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3answers
2k views

PIC Microcontroller timer

We want to be able to design a PIC microcontroller based timer. The specification requires that we have a time for at least one month (30 days). I have been trying to figure out how one can do that ...
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2answers
4k views

Using MSP430G2452 Timer + ADC

I'm trying to build a simple guitar tuner using MSP430G2452. The guitar's signal will come through its pickups, via an amplifier and 1kHz filter that I built using LM358. == Context == Now, my ...
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2answers
7k views

Is it possible to have 16 simultaneous PWM outputs on a 64-pin STM32F4 device?

From the STM32F405xx/STM32F407xx datasheet, I read that (at least) TIM2, TIM3, TIM4, and TIM5 have output compare units that can be configured to produce PWM signals on 4 channels each. If one ...
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2answers
647 views

What would I need to open a circuit (a usb cable) for a few seconds, on a given time?

I have a USB cable connected to a USB modem. On a specific time of day (say, at midnight - but it should be configurable) I would like to open the circuit for a few seconds. The result should be ...
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2answers
247 views

A strange uP timer problem

We use STM32F2 at work, I recently face with a strange problem. I do not expect a direct answer from the crowd but I hope some pointers where to look at for root cause. I have a clock that is 1MHz in ...
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2answers
635 views

Where is the oscilator in the 555 chip provided here?

I have tried a while to understand how the 555 chip is built, I opened the datasheet of TI available here : http://www.ti.com/lit/ds/symlink/lm555.pdf anyway this is the scematic from the datasheet ...
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2answers
2k views

Are my theoretical power consumptions of this avr correct?

After being inspired by a simple ATMEGA 168 based darkness alarm that has a theoretical life span of 3 years on batteries utilising sleep mode, I had decided to make something similar of my own (a ...
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3answers
16k views

How to produce digital pulses using 555 timer IC for stepper motor? [closed]

I need to run bipolar stepper motor with 555 timer IC. Is there any simple circuit to produce the pulses to rotate the stepper motor clockwise, anti-clockwise with the desired speed? If there are ...
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2answers
4k views

Creating 1 hour delay with 89C51 micro controller

I am writing an Assembly Program function for 89C51 which can create one hour delay. I can't use any other micro controller as only 89c51/52 is available locally. So I am stuck here because even when ...
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5answers
3k views

Maximum attainable delay with Micro controller

I am designing a microcontroller based delay circuit to implement delays of 2 hours, 1 hour, 45 minutes, and 30 minutes. The circuit will automatically turn on off a relay after this time period has ...
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4answers
11k views

Starting motor for 5 seconds after 30 minutes, turning it off and start in reverse direction after 30 minutes

I want to start a 9v DC motor in one direction for 5 seconds after 30 minutes delay, then turn it off and then after 30 minutes, restart it for 5 seconds in reverse direction and then stop it. The ...
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3answers
1k views

Does this timer circuit make sense?

I want to make a timer that counts down from 15 minutes, in 5 minute intervals. It should use 3 LEDs, and behavious should be such that when it is switched on, all 3 LEDs are lit. Then after 5 mins ...