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.

learn more… | top users | synonyms (1)

0
votes
0answers
30 views

Timer causes UART problem

I have a problem, found on both ATMEGA1284P and ATMEGA2560. I have set a 16-bit timer in CTC (tried both Timer1 and Timer5) to give an interrupt every 1ms so I can increment a 32-bit volatile time ...
0
votes
2answers
68 views

Turning on a 5v circuit with an 3.3v control signal (from a Raspberry PI) [duplicate]

I want to run a NE555 timer in astable mode, but I only want it to turn on when a 3.3v is supplied, I want to make use of a transistor to do the switching. At the moment i am using a 2N2222 ...
0
votes
0answers
23 views

digital power timer 1 min on off interval programmable for 1-3h [closed]

We have a home made (fire heated) copper heat exchange run with an eletric water pump ciculating to heat water in an outdoor spa. We need a timer that will switch the water pump on and off at 1 min ...
3
votes
4answers
122 views

Simple way to generate a two-level pulse?

I am looking to generate a two-level pulse as follows, where the adjustable parameters are \$V_1\$ and \$V_2\$ between 0 and ~5V, and \$t\$, ~5 to ~50 ms: The trigger pulse length may be anywhere ...
0
votes
2answers
57 views

Monitor status of slow-switching (1 second) signal

I need to make a circuit that can look at a signal and turn an LED on or off if the signal is actively switching. The input signal turns off and on for a period of about 500ms, but sometimes will be ...
0
votes
2answers
78 views

What causes inaccurate time in 555?

I would like to use 555 with a relay to make a reliable control circuit. I use 555 as mono-stable and the following equation does not work: t = 1.1*R*C seconds R = 51 K ohm C= 220 uF The ...
0
votes
2answers
42 views

Alkaline Battery for Boost converter for 1000ma current requirement?

I am working on a very small scale project that needs 300-600ma bursts at 5v for 10-20 seconds (a bank of LEDs) followed by a period of low power consumption (around 10ma for around an hour or so for ...
0
votes
1answer
59 views

Power solenoid valve battery

I'm trying to make an Arduino controlled irrigation timer. My idea is to use an Arduino pro mini and a cheap solenoid valve, wired to a TIP120. However, from my calculations, it's impossible to run ...
0
votes
0answers
26 views

How to make 12 hours timer? [duplicate]

I want to make a timer that trigger every 12 hours and when it triggers it stays high for 30 min then reset again until another 12 hours, and so on. I want to make this circuit with the simlest ...
0
votes
1answer
73 views

Incorrect Manchester encoding from PIC microcontroller

I have written a C program for the PIC18F4620. My PIC works as an encoder, which encodes a data stream in Manchester code. My output is rd7, where it should appear the Manchester code, but only ...
-1
votes
0answers
44 views

STM32F103C8T6 pwm generation

I wrote this code to generate a PWM but I did not get an output. What am I doing wrong? ...
0
votes
2answers
92 views

Getting Clock/Time information from PC to an STM32F4

Assume I connect a microcontroller board (like an STM32F4) to a PC via USB. Is there anything in the USB communication protocol that contains host clock data? In other words, can I sync the ...
0
votes
1answer
31 views

8051 TH0/TLO flag values

I'd like to know how can I calculate TL0 values. For example, when we have assigned hex value 0x05 to TH0 flag, we set our timer reloading time for 250 microseconds. So the question is: how can I ...
0
votes
1answer
38 views

Knock Sensor using 555 Timer with a timed light

I have seen a few Knock Sensors using the Piezo Speaker and the Arduino. I am wondering if there is a way to eliminate the Arduino and utilize a 555 Timer and other simpler components so that when the ...
0
votes
1answer
47 views

How to generate 1min timer interrupt in PIC24F

I m trying to generate a 1 minute interrupt using pic24F seires... To be specific PIC24Fj64GA306 Here is the code snippet ...
0
votes
1answer
75 views

555 and transistors: using a transistor to ground the reset pin of a 555 and how to drive a MOSFET with a 555

Parachute Deployment Timer I am busy trying to build a parachute deployment timer for an amateur rocket using 555 ics What have I done thus far I have a switch that closes temporarily while the ...
-4
votes
1answer
73 views

What type of 555 timer circuit is this [closed]

Could someone please describe what sort of 555 setup/circuit is in the image and how it operates. This is the webpage on which I found it http://www.thefintels.com/aer/protected/timer.htm Thank you ...
1
vote
2answers
296 views

555 timer with output voltage equal to 5V?

I am (still) learning about electronic and want to get a 555 timer. From a datasheet (page 5) it looks like when the input voltage is 5V, then the output voltage is only 3.3V. Is that correct? If ...
1
vote
1answer
117 views

Can the STM32 DMA speed be controlled by the timer?

Is it possible to have the DMA controller on an STM32 transfer each packet only when a timer update event occurs or can you only control the start of a whole chunk of DMA? The use case is (on an ...
1
vote
1answer
41 views

Generating a clock from timer using PWM

I am using CC2640 from TI in one of my designs. As per the datasheet, I can output a clock of maximum 32KHz to any external circuit/IC. As per my design, I Need to provide 1MHz clock to a sensor. ...
0
votes
0answers
89 views

STM32 Encoder mode + Input Capture on the same timer

I want to use CH1 and CH2 in encoder mode and also CH3 in input capture mode, all this using one timer (TIM3). Is it possible? I didn't found any warnings in datasheet. I looked at the block diagrams ...
1
vote
2answers
45 views

Generating pulses via timer match output or timer ISR?

I'm using LPC1778 uC for a project and want to know what is the difference between generating pulses via timer match output and via toggling a pin in a timer ISR. What are the pros and cons of both ...
0
votes
3answers
154 views

How to implement precise delay function in Keil c51 (for c8051) that waits exact amount of CPU clocks, the number of clocks ranges from 1 to 255

So as the title says, I need exact delays, not too long, ideally in the range of 0 - 350 CPU clocks, but if anything would work in narrower range the absolute minimum range is 20 - 127 CPU clocks. So ...
-5
votes
1answer
53 views

Large timer interrupt instructions [closed]

Assume that it takes the micro-controller 1 microsecond to execute an instruction and the timer overflow has also been set to 1 microsecond and in the timer interrupt handler we have some instructions ...
1
vote
3answers
115 views

Uart Transmit every 1µs Interrupt StM32 NucleoF401-Re

I am using the STM32 Nucleo F401-RE and HAL libraries. I would like to send value through UART to the PC console every 1µs interruption. Actually I want every 1 µs interruption to increment a ...
0
votes
1answer
42 views

Why I am seeing a spike of 9V on output and capacitor in 555 timer

I would like to have high voltage at output initially for a period of time, then low and high ... . But in the following circuit, I see spikes on output (green) and capacitor (blue) for a short period ...
-2
votes
1answer
66 views

Help choosing component values for a relay delay circuit

I want to build a circuit that controls a relay with the following specifications: the relay should turn on and stay on for ~60 seconds after the button is pushed the relay should stay on as long as ...
1
vote
3answers
91 views

Deciding Timer Interrupt time

I have used timer interrupt in my application, mainly for timing reasons like timeout detection for processes,pulse generation etc, every 1 ms. Now i have a doubt. Suppose in main(), if im doing ...
1
vote
4answers
78 views

Purpose of Resistor - comparator

I am studying this time delay circuit and am curious to know the purpose of the 4.7kΩ resistor. As I see it, it has no purpose. I've built and tested this circuit with and without it and see no ...
2
votes
0answers
55 views

Implementing periodic sensor data storage and GPRS transmission

I am using custom hardware driven by a TIVA TM4C (specifically, TM4C123GXL) to control a microgrid with battery energy storage, solar panels, four loads controlled by relay, and a SIM900 GSM GPRS ...
0
votes
2answers
86 views

MSP430FR4133 timer interrupt

I am trying to use the timers on the microcontroller in order to count up to 10us then add 1 to the int timer. I intend to use this in a project I am doing where I count the time between pulses from a ...
0
votes
1answer
51 views

Triggering a LED and interrupting it quickly (with a PIR sensor). What do I need for this?

I'm an artist working on a interactive installation. I'm a beginner in electronics and I'm feeling a little bit lost here, can you help me? I have a 5v circuit with a PIR sensor activating a LED and ...
0
votes
1answer
58 views

I have this timer circuit. Push and release vs push and hold give me different times

I have a timer circuit which I slightly modified from the one in this link I have an image below of what my circuit looks like. My problem is this: When I push my start button and immediately let go,...
1
vote
1answer
69 views

555 autostart counting

In a monostable configuration of the 555: http://circuitdigest.com/electronic-circuits/555-timer-monostable-circuit-diagram I have connected pin2 to the ground all the time. My goal is that once the ...
1
vote
3answers
112 views

8 bit PICs: timer1 asynchronous vs synchronous operation

The 8-bit PIC family (I'm working with pic18f46k22) offers some timers (timers1/3/5) that can work in both asynchronous and synchronous modes when clocked from an external source. The obvious ...
0
votes
3answers
90 views

Servo control using dsPIC33's Output Compare and Timers

I am trying to control a single servo using output compare and a couple of timers. Timer 2 provides the 20ms period and it controls output compare 1 (OC1). OC1 is running in continuous pulse mode, ...
1
vote
1answer
28 views

Circuit that randomizes shut off time to LED's from 1 - 3 seconds when switch is thrown

I have been asked to create a circuit that drives a set of LED's that when switched off uses a random timer from ~1 - 3 seconds before the lights go off. This will be used in a light signal box for a ...
0
votes
1answer
60 views

555 timer digital clock

How would you go about connecting a 555 timer to a circuit with a 16x2 LCD display, which is already connected, to create a digital clock that counts the time? Do you have a sample of how this code ...
1
vote
1answer
69 views

ATmega48PA: can not run PWM on OC0A and OC2A pins

I have some troubles trying to run Fast PWM on OC0A and OC2A pins. The code is the following: ...
0
votes
1answer
51 views

Setting up a counter on STM32F405xx

How do you correctly setup Timer9 (TIM9)on an STM32F405xx to count pulses on rising edge? Is there a special configuration for the pin to the timer outside of this short example? Here's what I've ...
0
votes
1answer
42 views

555 delay circuit is unsatble

Hello I have built the 555 delay power off circuit by using these 2 guides: home.cogeco.ca/~rpaisley4/LM555.html#30 http://www.electroschematics.com/5963/adjustable-timer-1-10-minute/ I using a ...
2
votes
1answer
72 views

AVR PWM output delay before start

I'm using an ATtiny85 to generate a PWM output (using Timer0 in OCR mode), and this PWM output is being switched on and off at regular intervals. I am finding that when switching on the PWM output, ...
0
votes
3answers
120 views

Is it possible to call Timer ISR when we want it to execute.?

I am using PIC32 and I am doing a timer example. I am using the example of Timer1 provided in microchip documents. My understanding with the timers is when our main program start, timer also start ...
4
votes
6answers
450 views

Calculating Milliseconds using timers in PIC and synchronizing it with DS1307 timing

I have used DS1307 in my project which gives me the values of Hour, Min, Sec but I also need values of Milliseconds. I am ...
0
votes
1answer
101 views

Transistor delay switch equal to a SPDT Relay

I have a circuit I need the functionality of a SPDT switch that is flipped a couple of seconds after power is applied. It is just switching data lines on a USB port so there is no current being ...
0
votes
1answer
69 views

Timers and counters

I have to build a ladder diagram for a system which sounds the alarm if inside 60 seconds after pressing the start button,10 objects have passed.The alarm goes on until we press stop.In the system we ...
0
votes
1answer
106 views

Count pwm pulses on pic

I'm working on PIC18F8722 to generate PWM for 50% duty cycle. I have obtained the PWM and now I need to count the PWM pulse. As per my knowledge we can use timers to generate and count those pulses ...
0
votes
2answers
68 views

PIC16 10hz timer with timer1 and 1Mhz clock

I need to increment a stopwatch at 10hz using timer1 on a PIC16F628. The external clock is 1Mhz, supplied by a packaged oscillator (EPSON sg8002db). With no prescaler, the value to set the timer to (I ...
-2
votes
2answers
134 views

Count external clock pulses for a predefined time interval (PIC16f877a)

I need to count external clock pulses for a predefined time using PIC16f877a. I don't know what to use, whether counter or timer or both. I don't know to use timer and counter modules of PIC16f877a. ...
0
votes
2answers
136 views

Is it possible to implement a fail-proof watchdog timer in software?

I want to add a piece of code for watchdog timer within my source code so that the board resets automatically when programs hangs. I am using Mediatek Linkit One board.