Calculation slew rate rise time ?

R!f@@

Joined Apr 2, 2009
9,682
OK..and ?

If you know about programing you could make a counter between two events.
 
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Papabravo

Joined Feb 24, 2006
12,702
Here is the basic idea. When the test signal rises above the 10% level you turn on an enable signal. When the test signal reaches the 90% level you turn off the enable signal. You arm a counter to start at zero and count up with a manual RESET. When the enable signal goes to logic 1, the counter stars counting, when the gate signal returns to logic 0, the present value of the counter is held until the next manual RESET.
 
Simplisticly:

peak detect
Valley detect
Find 10%
Find 90%
Time from 10% to 90%

Ringing can mess up results. There's time and voltage resolutions and quantization errors and accuracies.
Make an assumption that wave is periodic.
Rise time or rise and fall time?
So, you would need to do some sort of peak/valley detect without detecting the ringing.
 

Thread Starter

Mehmet Salih Aslan

Joined Feb 12, 2017
6
Thank you for your answers.
Of course I know microcontroller programming.

I install ADC and measure voltage values from 10% to 90%.
Start timer when adc = Vpp * 0.1
Timer stops when adc = Vpp * 0.9

Thus, rise time is found.
Rise time is usually 5us.
Can I measure 1us with a timer?
 

Papabravo

Joined Feb 24, 2006
12,702
Thank you for your answers.
Of course I know microcontroller programming.

I install ADC and measure voltage values from 10% to 90%.
Start timer when adc = Vpp * 0.1
Timer stops when adc = Vpp * 0.9

Thus, rise time is found.
Rise time is usually 5us.
Can I measure 1us with a timer?
You're going to need a very fast micro to measure smaller times. The method I outlined in hardware should work up into the 100's of MHz. with readily available components.
 

Thread Starter

Mehmet Salih Aslan

Joined Feb 12, 2017
6
That is irrelevant to the discussion. A 10 kHz. square wave can have a rise time of 2 nanoseconds without any trouble at all. You are the one that said you wanted to measure 1 usec. or so.
I have no idea how many seconds it will be. I'm just guessing. If nanoseconds is the microcontroller can not do that.
 

LesJones

Joined Jan 8, 2017
2,419
You do not seem to have established the FULL specification of the device you need to build. (Or if you have you have not passed it on to forum members.) If you have not been provided with this data then you could well have already lost marks by not asking the question.

Les.
 
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