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How to Generate a variable duty cycle PWM of a constant frequency in Simulink
hi...can anybody help me modify this coding..this coding only generate 50% duty cycle..if possible i want to generate variable duty cycle..:cry: program PWMBoost main: TRISC.2 = 0 ' CCP1 (PortC.2 = Output) PR2 = 110 ' Set PWM Period for approximately 45KHz CCPR1L = 55 ' Set PWM (...)
Dear All, How to generate variable duty cycle with same frequency PWM Signal using DSP processor? DSP Processor using : TMS320F28335 Texas Instruments. Thanks & waiting for support to enhance the knowledge,:smile:
Hi, I would like to draw your attention to the CMOS version of the 555 circuit, the LMC555 from National Semi. or TLC555 from Texas Inst. and the astable mode working frequency is claimed to be 2MHz typically at Vcc of 5V. Its data sheet includes a diagram for 50% duty cycle operation too. See this link (...)
Hi to all... I'm a beginner and I need a simple circuit that convert a signal of 150hz with variable duty cycle (from 0 to 100%) to a constant voltage proportional to the duty cycle... I have tryed to find in internet, and I think that I need a lc filter (i am not sure...) , but I not say how calculate the (...)
My function generator Square waveform output does not have a duty cycle adjustsment parameter What kind of circuit/network can i hook up to it so i can adjust the 50% squarewaveform to any duty cycle % percentage from 0% to 99%?? What circuit can do this please? My Triangle output does NOT have a "Symmetery" (...)
First of all Hello everyone!! I have a problem a very big one I am new to verilog and i have a Spartan 3E FPGA Starter ,i am facing a rather difficult problem for me i want to create a verilog code to make a frequency generator from the 50Mhz Spartan s internal oscillator i need a frequency generator with frequency between 1Hz and 10Khz from th
Hi, I'm aware that PIC microcontrollers are capable of detecting PWM input signal with so-called CCP module. I was wondering whether PICs can measure the duty cycle of a 10kHz PWM signal and program it to drive a few LEDs depending on the duty cycle. Is it possible? or is it better to use an RC filter to convert the (...)
I have an incoming variable frequency (1 KHz to 20 KHz) and variable duty cycle pulse. I need to convert the duty cycle into an analog voltage between 0 and 1. I do not have the luxury of RC filtering the pulse using an external capacitor. What is the simplest way to implement this (...)
What will happen ???!!!!! what do you mean by that ? what do you want to do exactly ? you have a 555 TIMER , if you set it as A stable , it will work and oscillate as well . if you change D.C no thing special will happen . i don't know what is your exact aim .
Hi all. I've got a doubt about the adjustment of duty cycle for an astable multivibrator using 555. If you have a circuit for a timer with 1kHz please send it. Thank you
pins 6 and 7 are connected to the resistors reversed, see the schematic 555 and 556 Timer Circuits Alex
Hello experts! I have a question related to 555 timer in monostable mode. I have been given with a question in my electronics examinations. Question was: Why 555 timer in monostable mode always has a duty cycle greater than 70%? I didn't figure out this question. A similar question to this: Why (...)
can i use the Control pin of 555 timer to change duty cycle without changing the set frequency? to be more precise, i want to set a frequency in the circuit using a potentiometre. and when i change the potentiometre_2 the duty cycle must change without causing a change in frequency. I doubt if this is (...)
How to make 555 Astable multivibrater for 1 Hz? duty cycle On Time=0.1 ms, Off time=999.9 ms. Or Which is the best way for 0.1 % duty cycle in 1 Hz. Thanks in advance.....
Hi all! Does anyone know how to calculate the duty cycle of this circuit? the frequency =1/RC
Hey I might not be able to give schematic now but you can use 555 timer IC to produce a clock.The duty cycle of that clock can be directly controlled by resistor by switching between resistors you can vary duty cycle. There are circuits for independent controls for both frequency and the (...)
I am studying the DC-DC converter and using it to drive a LED. Now I am designing a current mode PWM which control the switch at constant frequency and variable duty circle. I look up some IC's datasheets and I'd like to design it just like the LM3410 of National Semiconductor or TPS61042 of TI. But I don't know how can use the PWM to provide t
Hi friends i want to know how to vary the duty cycle in program.I am using PIC controller.I am trying for PWM program for LED intensity control.
You will not get a symmetric square wave with only the 555 (50% duty cycle) and a variable output frequency will change the duty cycle also. Try another IC like XR2206.
Hi, I am posting a simple circuit to obtain perfect 50% duty cycle square wave. Frequency is fully depend on R1 and C1
I don't really see the problem: at 150Hz the period is about 6.67ms. So if your filter has some 65ms time constant, you should be OK. With ony a 62k resistor you need about 1uF of capacitance. That can be even a surface-mount 0603 for voltages of 6V or maybe even 10V. I am sure you can use a 555 to discriminate between the two (...)
Hello to all !!!!!!!! I have designed the astable multivibrator using 555 which has been modified for variable frequency and variable duty cycle ranging from 30 to 80% using two diode but problem is with me is i am not getting the desired output of pulses when i am trying to get for 5 kHz freq. but the (...)
hi, i have a buck converter and the switch is controlled by a pulse source. I have designed it in hspice . What i want to do is to control the pulse source with variable pulse width but hspice doesn;t give me that option. Can anybody tell me how to change pulse width in time ,and having the Vpp constant?? thank you
Hi, Somewhat I don't understand if I'm asking for the right thing or not, but still, I need to produce variable frequency Square wave ranging from 0 - 2 Hz. The variation will be controlled with a 10k pot (for this I think a variable voltage from 0-5 volts on 10-bit adc input of controller will do the job, 1024 parts of this frequency range will
One option is to feed this 50% square wave to 555-timer (monostable operation) and adjust R-and-C so the output wave has required 10-20% duty cycle .. Here is info on how to calculate T with 555-timer: Rgds, IanP
Hello, When your PWM is running and you want to change the duty cycle: I would just write a new value to the CCPR1L register and then I guess it changes on the next instruction in the PIC? But how will the transistion look like? will it automaticlly wait until the next period or just change abruptly? Or is there an "elegant" way of programm
Yes, the 555 is too slow to do this. As FvM wrote above, use two monoflops. The HC123 is a dual monoflop, working at 2...6 v, min. output pulse width < 100 nS ...
The post is based on wrong assumptions. 555 is available in inexpensive SO case, qualified for 125°C, e.g. from TI.
There are also many on line calculators, they can do the job but I'm not sure if you will learn anything. Alex
The circuit in post #1 can't achieve 50% duty cycle by nature. There's apparently a problem with the said online calculator or a misunderstanding. A 50% duty cycle circuit is shown in the 555 datasheet. Another popular circuit uses a single resistor between output and capacitor.
So Im reading a 100Hz frequency from an MEMSIC 2125 and I need to find the duty cycle which i will later use to find the angle. For now I am just trying to find the Ton = Rising - Falling. Here is my Code. I am supposed to get a duty of about 0.6 but when I run the code and look at the watch I find the diffrence between the rising (...)
You can do this simply by using an 555 chip (or variant). Like this
I don't agree about "unusual". A 555 circuit with feedback from output instead of DISCHG pin can be already found as 50 % duty cycle oscillator in the LMC555 datasheet. The variant with diodes and variable duty cycle is at least frequently used.
hi, can some one tell me what is the mistake in this code i am not getting output on cro. interrupt service routine code for INT0 int p_rpm;//global variable. { int c_rpm;//current rpm c_rpm=TCNT0;//loading the value of timer0 to current rpm if(TOV0) { rpm=(TOV0*65535)+(c_rpm - p_rpm)/freq;//calcul
Hello there,I would like to control a TRIAC through MOC3020 for that I am generaating a PWM signal which has a duty cycle corresponding to the increase or decrease of variable resistor in right or left direction. can you please help me to do that me I am now using an adc but it is not working perfectly,see my codes with adc module: #includ
You might be able to adapt a technique used to alter duty cycle on a 555 pulse generator. Diodes change the charge/discharge rates on the
I want to make a perfect 100 kHz pulse with 50 % duty cycle. If a perfect 200kHz pulse can be generated, I know how to make it 100 kHz perfect 50 % duty cycle with flip flop. So I want the best solution to make a 200 kHz pulse generator. Does 555 timer (bipolar one) make a perfect 200 kHz pulse? In the (...)
I'm trying to measure on time of a PWM signal using dsPIC30F4011 (Input capture mode), when I increase duty cycle of my signal from 20% to 50% it show correct value , but when increase it form 50% to 80% it's again display 50% to 20% duty cycle on my LCD display. Can someone help me, why this is happening .
Hi masterx81, if your power source is DC, what you say (variable duty cycle with 555) is OK (for AC you could use a phase control wuth triac). A power MOSFET (as IRF520 or 6N10 among others) will be better than a bipolar transistor. It has very low ON resistance and very fast switch, so no power consumption. The gate can (...)
hi........ could any one help me to figure out the relation between 50% duty cycle and speed factor in FPGA.? any links or documents.? How far I need to keep the 50% duty cycle as Iam planning to boost the frequency from 20Mhz to 300Mhz.?
Hi , I have to transfer a data from Flip flop1 to Flip flop2,Flip flop's hold time is '0' and clk to q delay is 'x' ns.Between Flip flops there are combinational logics which takes 'y' ns.I'm having a pulse whose high period is more than 'x' ns.Its duty cyle is 20% high and 80% low.Can I use this pulse or is there any need that I have to use
can anyone tell me how to divide clock by 4.5 with 50% duty cycle, with minimum amount of HW/flops niks
Hi, What should be the duty cycle of an IR transmitter emitting square waves of say 10khz ? how does duty cycle matter in communication ? Any adjustments to be made in receiver module for a particular duty cycle? Thanks
Hi, This can easely be done with two old NE555. The first one as astable oscillator followed by a second in a monostable configuration. The first one determine the frequency and the second determine the duty cycle. Datasheet : = t
Halo, anyone has any idea how to implement a 50 duty cycle compensation circuit at the output ? thanks
HI .. Do anyone have ide about external PLL which can do cuty cycle correction of 20Mhz duty cycle is 25%-75%..... Please suggeest me some external PLL whcih can do this operation Jay
Hi there, I'm a newbie in using PIC microcontroller and would like to ask something regarding the duty cycle of a PWM coding. If its not too much trouble, can anyone briefly explain how do I determine the duty cycle of a PWM duty cycle in the coding? Is it true that 255 (decimal) is (...)
Hi all, When I read the data sheet of Micrel's 868MHz receiver, it mention that shutdown mode for >10:1 duty-cycle operation. But i am not understand the meaning of "10:1", can anyone explain for me? Thanks x 1000 BR Mac