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.
1
vote
3answers
202 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 ...
1
vote
2answers
252 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 ...
1
vote
1answer
157 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...
...
2
votes
2answers
406 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 ...
0
votes
1answer
142 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 ...
7
votes
1answer
209 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 ...
2
votes
6answers
386 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 ...
1
vote
1answer
81 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).
...
5
votes
3answers
477 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).
...
6
votes
1answer
477 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 ...
1
vote
1answer
184 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 ...
0
votes
0answers
160 views
Activating timers in beaglebone
I m currently running ubuntu 10.10 on my beaglebone. I have also updated the kernel to the latest version. In my project I have to use timers for timing. Unfortunately in pin mux utility the ...
1
vote
0answers
204 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 ...
3
votes
1answer
602 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 ...
3
votes
2answers
319 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 ...
4
votes
1answer
597 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 ...
2
votes
1answer
216 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 ...
-2
votes
2answers
551 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 ...
3
votes
3answers
184 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 ...
3
votes
3answers
1k 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 ...
1
vote
3answers
234 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 ...
3
votes
1answer
389 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. ...
3
votes
3answers
387 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 ...
2
votes
1answer
2k 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 ...
4
votes
2answers
916 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?
3
votes
1answer
169 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 ...
4
votes
5answers
1k 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 ...
2
votes
3answers
123 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 ...
3
votes
2answers
2k 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 ...
2
votes
1answer
1k 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?
1
vote
1answer
452 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 ...
0
votes
2answers
706 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 ...
1
vote
0answers
950 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.
== Some background ...
3
votes
2answers
775 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 ...
2
votes
2answers
339 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 ...
3
votes
2answers
198 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 ...
2
votes
2answers
212 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 ...
11
votes
2answers
636 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 ...
2
votes
3answers
3k views
How to produce digital pulses using 555 timer IC for stepper motor?
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 ...
-1
votes
2answers
1k 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 ...
4
votes
4answers
804 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 ...
1
vote
4answers
2k 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 ...
0
votes
3answers
296 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 ...
0
votes
1answer
334 views
How do I set the speed of a 4060B chip?
Apologies if this is a bit simple, but I'm new to this!
How do I set the speed for a 4060B chip? I want it to trigger every 5 minutes (fairly accurately).
I've looked at the instructions here: ...
2
votes
4answers
2k views
How can I make a 15 minute egg timer circuit?
I want to make a 15 minute timer for a game. I would like it to count down 3 x 5 minute segments of time, and then ring a bell when the 15 minutes is up.
To do this, I want to push a button to ...
2
votes
1answer
173 views
What does granularity mean?
I was wondering what granularity means? It is used in the context of:
A background task that performs a simple operation. The granularity of the background task, specifying the number of ...
1
vote
3answers
384 views
Electrical locking mechanism (on timer)
I'm looking at making a very basic, automatic cat feeder for the odd occasion I'm not around at 2pm when she gets fed. I figured I'd keep things simple by having a door that is spring loaded, but held ...
0
votes
1answer
114 views
what is the default internal clock for pic16f1946?
While going through the data sheet, section 5.3.1 says: "Default system oscillator determined by FOSC bits in Configuration Word 1". How can find the value of this default clock, is it 8MHz or 31khz?
...
9
votes
4answers
475 views
Low power, low voltage, slow (0.1Hz) oscillator?
I had the opportunity to analyze a very interesting circuit today using a programmable unijunction transistor as a timer.
The power supply varies, and the circuit must operate on under 10uA of ...
1
vote
1answer
329 views
I having troubling understand what other interrupt firing besides TMR2 on PIC18f4550
I having troubling understand what other interrupt firing high_isr besides TMR2 on PIC18f4550.
Way I detect it I set pin MY_DBG_PIN toggling everytime high_isr is activated, and from what I try to ...
