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Counting number of pulses

Hi all,

Here is my understanding of counting number of pulses of my project:

Please be patient in my description may looks lengthy..

In this mode(process of number of pulses), we can measure the number of pulses coming on the input line =91Pulse_din_0=92 within some time set by the processor. There is one counter =91CNT_P4P_PC0=92 to which processor will load the time period value, during which number of pulses have to be counted.

Suppose we want to calculate the number of pulses coming on the input line =91Pulse_din_0=92 in the duration of 1 second, then processor has to load the value of =910x186A0=92 (for the =9110usec=92 time base i.e., actua= l time divided by time base will give the count value to be loaded into counter) to the =91CNT_P4P_PC0=92 counter. Then this counter starts decrementing at the rate set by the processor and at the same time PC_0 starts incrementing it count value by 1 on receiving the pulse on input line each time. This process will be continued till loaded counter =91CNT_P4P_PC0=92 reaches the value of zero. At the end, if we read the count value of PC_0 counter, we can get the number of the pulses arrived on the input line during set time period.

Could anyone give or form an equation of counting number of pulses (confusing what is Actual time here...) with an example

Please ...response..

J.Sreeniv Design Engg-FPGA, MOOG,Inc

Reply to
JSreeniv
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On Apr 18, 9:25=A0am, JSreeniv wrote: > Hi all, >

Good Lord. What are you actually trying to do? I've read this a couple of times over a couple of days and it makes no sense to me - and apparently anyone else judging by the responses you're getting. How fast is the pulse rate? How many pulses per count period? Explain this better.

G=B2

Reply to
stratus46

Ok, you've got your two counters: CNT_P4P_PC0 from your description it has a 10 usec time base so you load it with ?0x186A0? (which is 100000 decimal) It starts counting down to 0. When it reaches 0, it will have counted for 1 second. I assume it will give you an interrupt at this point.

PC_0 From your description, I assume this is connected to Pulse_din_0 pin. Your external pulses appear here This counter counts up by 1 with each pulse. When CNT_P4P_PC0 reaches 0, then 1 second has elapsed and you should simply read the value of PC_0. The PC_0 counter will contain the number of pulses in 1 second. (pulses per second: pps)

Since frequency = pps = Hz then the frequency of the pulse train can be directly read from your PC_0 counter value.

Reset PC_0 to 0 and reload CNT_P4P_PC0 and do it again, if you want an average value over a few counts.

There is no equation that I can see, as you can read the frequency of the pulse train directly from the PC_0 counter.

The problems arrive when you want to count very fast frequency pulse trains, and then a 1 second gate (CNT_P4P_PC0 = 0x186A0) is too long and your PC_0 counter will overflow (depends on how many bits in PC_0)

In that case, you will want to reduce the counting window (the gate), counter CNT_P4P_PC0, to a narrow window of 1ms, for example.

For a 1ms gate: 1ms / 1us = 1000 = 0x3e8 so load CNT_P4P_PC0 with 0x3e8 Reset PC-0 to 0 and start the counter CNT_P4P_PC0. Now, when CNT_P4P_PC0 counts down to 0, you must read PC_0. This value in PC_0 is the number of pulses in 1ms. Multiply this number by 1000 to get the actual frequency in Hz (or read it directly, as it will be in KHz).

John.

Reply to
John Smith

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