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.
-5
votes
2answers
66 views
How does the 555 timer IC circuit work?
As a beginner to electronics I'm having a tough time understanding circuits that have a combination of different components, including the following timer circuit. Its based around a LM555 timer IC. I ...
5
votes
3answers
139 views
five month countdown timer circuit?
I'm a beginner in electronics, so I just have an idea in my head and don't know how to actually make it. I want to make a countdown circuit, for an event in next 5 month. The display format is like ...
6
votes
4answers
110 views
Can I achieve a one shot button without a 555?
I have a complex circuit, but my problem only relates to one small part.
I have a relay, which is energised by pulling the low side low using an NPN. I would like a pushbutton to operate the ...
3
votes
1answer
67 views
PIC interrupt based soft UART timing trouble
I've tried to implement a software UART on a PIC18F452 using TIMER0 interrupts and I can't get the timing working.
I'm using MPLAB ASM for compilation and the PICkit2 for programming.
...
3
votes
2answers
82 views
Use PWM and ISR at same time on AVR
Is it possible to use AVR PWM outputs and ISR interrupts at the same time?
I've got a project I'm trying to do on an ATMega328P and I need 3 PWM outputs but ALSO need to be able to use ISR interrupts ...
0
votes
0answers
11 views
Difference between Max Interface Clock and Max Timer Clock?
I am trying to use a timer from STM32F4 with ARM Cortex-M4 chip. I need to get the maximum frequency out of that timer for my ...
-4
votes
0answers
29 views
Timer map for the timers currently used in microcontroller [closed]
I'm new to this microcontroller programming. I found this forum very informative.
I've to prepare a timer map. I would like to know what exactly that "timer map" will contain.
Any examples or links ...
0
votes
0answers
121 views
stm32f2xx external clock source for timer
I trying to use a timer with an external clock source on a stm32f207ZE microcontroller.
But it isn't working. Here is my code:
...
4
votes
3answers
70 views
Creating a Sequenced Array of 3 Mosfets with Adjustable Timings
I am comfortable with rudimentary 555 circuits and other basics, but I have something a little bit beyond me now.
I need to have three separate mosfets A, B, and C all turn on and off in sequence. I ...
1
vote
1answer
79 views
Using capacitor to maintain current flow past opening of switch
This circuit turns on the motor when something blocks the beam from the LED to the phototransistor. I want the motor to remain on for 5 seconds after the beam stops being blocked (i.e. from when the ...
2
votes
2answers
208 views
Can I generate 56kHz signal with MCU running at 1Mhz
I am new to embedded systems designing. I have to generate a 56kHz signal with a MCU running at 1Mhz. I want high accuracy. If I just use a timer, it gives me 55.55kHz.
Is there any way I can divide ...
6
votes
1answer
143 views
AVR timer speedup on ATmega328
When running at clock prescaler of 64 on ATmega328, one of my timers speeds up for unknown reasons at a particular time in the execution.
I am using two timers on ATmega328 to generate the clocking ...
4
votes
5answers
113 views
4 or 5 Time Constants to reach practical potential?
While I'm aware that a component can never "fully" charge or discharge to 100%, one textbook I'm using (Practical Electronics - 6th Edition, Sinclair, Dunton) says that we can assume a component has ...
0
votes
1answer
57 views
PIC24H delta time calculation
Hello I'm making a project for my intro embedded software class and I need to make use of a timer in a program. If I'm not mistaken this code should be looping the while for at least 500 ...
2
votes
3answers
124 views
how to create a square wave with large duration and high duty cycle
For a "plant waterer circuit" I would like to add a safety feature that prevents watering for over ~3 minutes, and delays the next watering from occurring for ~12 hours.
Currently the circuit is ...
2
votes
2answers
98 views
How to reduce Timer error of Atmel 89S51 microchip?
I wrote a simple code counting 30 seconds using Timer 0 (Mode 0, it's 13-bit counter) of Atmel 89S51, and I used Proteus to simulate. After 30 seconds the LED light should be turned on.
I found that ...
2
votes
4answers
171 views
I need help designing a very simple timer
I'm designing a very simple led light timer based on the Pomodoro time management technique. For those of you unfamiliar, you work for a set amount of time, take a short break, and repeat.
My end ...
2
votes
1answer
80 views
PIC18 - problems getting inline assembler routine to work
(EDIT: Added C18 disassembly code)
I need to optimize a function written in C for a PIC18f4585. I am using C18 to compile.
The function I am trying to re-write in assembly is:
...
0
votes
2answers
292 views
Frequency measurement with STM32
This question is mainly a query for an advice.
I am trying to implement a frequency meter on STM32F4.
Up to this point I have a working ADC converter with DMA and a timer which checks for the current ...
0
votes
2answers
173 views
Building a 12 hour timer
So, i want to make a timer that will turn on/off a circuit. I want to turn on the connected device at 08:00 and stop it at 20:00, so the interval is 12 hours. Correct me if i'm wrong but i can't use ...
0
votes
0answers
450 views
Understanding Timers, Counters and Prescaler Registers on the STM32
So I'm trying to set up a very simple periodic interrupt on my STM32VL-Discovery board using the libopencm3 libraries on linux. I've looked at the documentation and I just want to verify with ...
-3
votes
2answers
299 views
what is 555 Timer? [closed]
what is timer 555 ??
can any one give me some links which talk about this topic ?
or some references ? or texts ?
how can we use this kind of timer ? how to create it ?
any information will be ...
0
votes
1answer
186 views
why will my transistor (TIP122) NOT switch?
My goal is to make a car turn signal flasher.
I used a 555 chip as the timer with the output driving a TIP122 transistor at BASE and a 100 ohm resistor between the BASE and the 555 output pin 3. The ...
1
vote
1answer
230 views
How to use watchdog timer in ATmega128
I am working with an ATmega128 and need to reset the microcontroller after some 10 seconds has passed and the user has not interacted with microcontroller. As an example when the user has not pressed ...
2
votes
3answers
238 views
Reading from multiple sensors and synchronizing data
I am working on a project which requires reading from four sensors simultaneously with time stamps down to millisecond.
Right now the best I can come up with is to use four PICs to read from each ...
1
vote
1answer
39 views
DSPIC30f timer1 not trigger everytime on POR
I am using timer1 on DSPIC30f4011 to generate an interrupt every one millisecond. However, the timer1 ISR is not executed every time on POR (2 out of 10 times). If I turn on the power for the chip and ...
-2
votes
1answer
73 views
How can i make a timed circuit which switches on at a certain time? [closed]
Tbh, I have no background in making any electronic stuff. I have always been a computer programmer but this is one instresting application I wish to develop.
We have an immersion rod for heating ...
0
votes
1answer
120 views
How to show PIC cycles in MPLAB when using PICKit?
The MPLAB SIM has a nice stopwatch that shows the cycle count. But when using a PICKit 3, the stopwatch is not there. Any suggestions on how to bring this function back?
5
votes
3answers
465 views
0-10 second on-time with a potentiometer
I would like to make a simple circuit, where the a potentiometer controls a 0 - 10 second on-time.
If the potentiometer is set to min, the on time should be 0 seconds. If the potentiometer is maxed ...
3
votes
3answers
242 views
Simple Metronome Circuit w/ Linear Pot Control
I'm trying to design a square wave oscillator to control an LED with a LINEAR frequency control range of ~0.017 Hz to ~17 Hz (1 BPM to 1000 BPM).
EDIT
Oli's excellent answer and circuit indeed make ...
2
votes
1answer
85 views
Timed switch between 2 psus
Lets say we're in a car application, for the sake of argument.
We've got the 12v cigarette lighter adapter line (which is turned on when the car is on and off when the car is off), a 12v line ...
0
votes
1answer
102 views
Performing different actions on the same timer
I am working with MC9S08AW60 on the Board-DEMO9S08AW60E. I have written the following code to perform Serial Comm, LED sequence and Keyboard Tx-RX.
...
3
votes
3answers
178 views
Arduino sampling accelerometer
I have an analog accelerometer I want to sample at 100HZ, I also want to plot the data with time of each sample so I have acceleration over time. To keep track of time I was going to use millis(). To ...
1
vote
3answers
112 views
what do you call a switch/relay which switches on an appliance for a given set of time?
I need a relay/switch, which would have a push-button switch upon which the button is pressed, it would power an appliance on.
I have a water pump, and it's water pressure switch is defective. I ...
2
votes
3answers
439 views
0
votes
2answers
165 views
PIC: Watchdog timer off by a factor of 4
I have a PIC16 (datasheet here) for which I use the watchdog timer. I configure the watchdog timer as follows:
WDTCONbits.WDTPS = 0b01110;
According to page 105 ...
4
votes
2answers
627 views
Fading RGB led with ATtiny2313 timer
I'm trying to make mood lamp with only hardware PWM and interrupts (i. e. main loop should be empty). I'm doing it as a challenge to learn how timers work, not for any practical reason. So far I've ...
1
vote
2answers
208 views
How to create small engine with timer
I'm not sure that this is the correct place to ask, but I have had great success with questions on the other stackexchange sites, so I'll try my luck :)
I need a device, which can press a button on a ...
1
vote
2answers
100 views
Accurate ADC sampling with in-accurate clock
Im building a datalogger with a LPC11xx as CPU. It needs to wakeup at 256hz to take ADC samples, but this CPU has very in-accurate timed wakeup from deep-sleep, causing jitter on the sampled data.
So ...
-3
votes
1answer
81 views
Reticulation Controller [closed]
I'm thinking of building my own reticulation controller to drive an automatic watering system. Does anyone out there have a good circuit diagram? A simple 6 or 8 station control with adjustable timer ...
1
vote
1answer
183 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 ...
1
vote
1answer
220 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 ...
6
votes
2answers
997 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 ...
3
votes
2answers
201 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 ...
2
votes
2answers
95 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.
...
2
votes
3answers
284 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 ...
3
votes
2answers
313 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 ...
1
vote
3answers
198 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
232 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
153 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...
...
