Pulse width measurement using pic microcontroller
Pulse Width (PW) is the elapsed time between the rising and falling edges of a single pulse. To make this measurement repeatable and accurate, we use the 50% power level as the reference points. Pulse Repetition Interval (PRI) is the time between sequential pulses. Feb 20, · So pulse width is basically a on time between a positive edge and a negative edge. So if we can measure a time between a positive edge detection and next negative edge detection, we can easily measure pulse width with respect to time.
The pulse width is a measure of the elapsed time between the leading and trailing edges of a single pulse of energy. The measure is typically used with electrical signals and is widely used in the fields of radar and power supplies. There are two closely related measures. The pulse repetition interval measures how to measure pulse width time between the leading edges of two pulses but is normally expressed as the pulse repetition frequency PRFthe number of pulses in a given time, typically a second.
The duty cycle expresses the pulse width as a fraction or percentage of one complete cycle. Pulse width is an important measure in radar systems. Radars transmit pulses of radio frequency energy out of an antenna and then listen for their reflection off of target objects.
The amount of energy that is returned to the radar receiver is a function of the peak energy of the pulse, the pulse width, and the pulse repetition frequency. Increasing the pulse width increases the amount of energy reflected off the target and thereby increases the range at which an object can be detected.
Radars measure range based on the time between transmission and reception, and the resolution of that measurement is a function of the length of the received pulse. This leads to the basic outcome that increasing the pulse width allows the radar to detect objects at longer range but at how to measure pulse width cost of decreasing the accuracy of what to cook for new years day for dinner range measurement.
This can be addressed by encoding the pulse with additional information, as is the case in pulse compression systems. In modern switched-mode power suppliesthe voltage of the output electrical power is controlled by rapidly switching a fixed-voltage source on and off and then smoothing the resulting stepped waveform. Increasing the pulse width increases the output voltage. This allows complex output waveforms to be constructed by rapidly changing the pulse width to produce the desired signal, a concept known as pulse-width modulation.
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PIC Microcontroller tutorials
From Wikipedia, the free encyclopedia The pulse width is a measure of the elapsed time between the leading and trailing edges of a single pulse of energy. The measure is typically used with electrical signals and is widely used in the fields of radar and power . Jan 21, · Working and operation of Frequency Measurement and Pulse Width Measurement using Microcontroller (AT89C51). The PWM signal (or any other waveform) is applied to the base of the transistor. Because the transistor functions as an inverter, Author: Ashutosh Bhatt. Jul 04, · This will measure OFF time because we are measuring inverted pulse width. Then again it waits for one cycle. Again timer will run till pulse is low. This will measure ON time. Both ON time and OFF time values are stored in four different variables. 2. Frequency function is an interrupt function. It measures number of pulses per second.
Frequency Measurement Pulse Width Measurement using Microcontroller and Circuit designers and developers need different measuring equipment, such as digital multimeter, CRO, DSO, frequency counter, logic analyzer, etc.
When designing any PWM oscillator or generator or have generated any waveform, it is necessary to measure either the frequency or the time period.
Especially in the case of the PWM generator, it is necessary to measure the frequency, the start time and the deactivation, and the most necessary is the duty cycle. And during testing and troubleshooting it has to measure all these parameters again.
Therefore, this is a time-consuming and time-consuming process. But they have to pay much more cost at least twice the CRO for this. Also, CROs and DSOs are only available in well-equipped laboratories, as they are not low-cost tools, such as digital multimeters.
So, fans may not have these tools in their personal home labs. The circuit is very simple, easy to build with fewer components, a micro-controller AT89C51 , an LCD and additional components such as crystal, capacitors, resistors, transistors etc. This figure illustrates the hardware connections for the frequency and pulse width measurement circuit.
The RW pin is connected to the ground. The Reset button is used to manually reset the micro controller. A RED indicator is connected to pin P1. The signal is applied to pins P3. This small circuit with a transistor and two resistors will turn any input signal into a square or rectangle shape and will limit the signal amplitude to Vcc ie 5 V max. The PWM signal or any other waveform is applied to the base of the transistor. Because the transistor functions as an inverter, the inverted wave is applied to pins P3.
The negative edge of the P3. This interruption will begin to count pulses on pin P3. The pulses are metered for exactly 1 second. After that, the internal stopwatch will measure the time in micro sec for which the pulse amplitude remains high which gives Ton value and the same for Toff value.
At the last duty cycle it is calculated using the equation. The LED indicates the counting and calculation process. Now, if the SPDT or slide switch is not in the repeat position, then the measurement process is completed, but if it is in the repeat position, the same process is repeated above and it continuously measures all four parameters. This complete operation is based on the program loaded in the microcontroller.
So now we understand the software. The complete program is divided into 9 different functions with one main function. Of these nine functions, five functions are intended for LCD manipulation, one for measuring start time and time off, one for measuring duty cycle, one stop function to measure frequency, and the last is the delay function. The last one is the delay function that generates an exact delay of 1 second using stopwatch 1.
It generates 50 ms delay using stopwatch and rotates it in a loop 20 times. Save my name, email, and website in this browser for the next time I comment. Please contact the developer of this form processor to improve this message. Even though the server responded OK, it is possible the submission was not processed. This small circuit with a transistor and two resistors will turn any input signal into a square or rectangle shape and will limit the signal amplitude to Vcc ie 5 V max Frequency Measurement and Pulse Width Measurement using Microcontroller AT89C