[SOLVED] counters for PIC uC.

[Raady Here]

PIC30F5011/ MPLAB 8.8

Hi,
Motor gives analog signal to my uC- I have to measure it voltage and frequency of signal, voltage is measured now by configuring ADC pins and reading through ADCBUF values.
how to measure frequency.

For measuring its frequency, I searched through some links where those say it can be done by frequency counter with configured timer0 as a counter, but none of them had any clear understanding.
if any body worked on frequency counter send me a link or sample where I can understand concept better about configuring timer as counter.

Regards,
Raady

 

[colin55]

There is already a .asm program:


Frequency measurement in assember (ASM) for PIC

 

[horace1]

with a dsPIC30 you can use the dsPIC library which includes an FFT
**broken link removed**

 

[Raady Here]

should i use the same adc pin for measurement of frequency?

 

[horace1]

should i use the same adc pin for measurement of frequency?

sample data using the ADC then feed it into the FFT - set the imaginary component of the samples to 0

have a look at application notes and sample code
https://www.microchip.com/wwwproducts/Devices.aspx?product=dsPIC30F5011

 

[kripacharya]

should i use the same adc pin for measurement of frequency?

It's not quite clear what you mean by (to paraphrase) "..frequency of motor signal..".
Are you talking about the rpm ? Is this a DC motor/ AC motor/ BLDC motor ???

Once you clarify this it will be easier to give helpful suggestions

 

[milan.rajik]

Motor gives pulse output for frequency measurement ? If yes, in PIC16F and PIC18F it is interfaced to T0CKI or T1CKI pin and respective timer is configured as counter. I have never worked with dsPIC. Maybe dsPIC has same pins or similar input pins.

 

[horace1]

if the signal is pulses no need to use an FFT (required for complex analogue signals)
you can connect the pulse data to a dsPIC "interrupt on change" input to count pulses
use a timer to count the pulses over known time period and hence calculate frequency

 

[Raady Here]

It's not quite clear what you mean by (to paraphrase) "..frequency of motor signal..".
Are you talking about the rpm ? Is this a DC motor/ AC motor/ BLDC motor ???

Once you clarify this it will be easier to give helpful suggestions

my client hadn't mentioned any hardware details of their hardware kit as how they are taking the measurement , they just gave me a output pin where I get an analog signal which i connect the same to my adc pin (on my board).
I am attaching a pdf ,

based on the 'voltage' and 'parameter' i want to check, i will automate the switches, if the measuring parameter falls in the correct range the voltage levels will be in the 'range values' else it will show 4.9v which means incorrect range. once i detect the exact range i make calculations to detect the actual value of the parameter based on the voltage level detected.

for parameters - 'IR', resistance, inductance, rotor resistance, i have made calculations and its is detecting correctly as i wanted.
but for parameters - Vibration, temperature, sound, current, i need to check frequency along with voltages if it falls in the range.

as i have only one pin where i can make measurement, with the same can i measure voltage and frequency.

in the links i have read, to measure frequency, from my understanding, they are configuring an interrupt pin and timer for counter and based on that they are measuring frequency, but in those cases the signal is digital.
but in my case i have only one pin which gives me a analog signal.
what can i do ?

- - - Updated - - -

if the signal is pulses no need to use an FFT (required for complex analogue signals)
you can connect the pulse data to a dsPIC "interrupt on change" input to count pulses
use a timer to count the pulses over known time period and hence calculate frequency

but horace1 ,
i am not getting any digital signal.
FFT is quiet tricky for to understand
http://www.microchip.com/CodeExamplesByFunc.aspx

are there any simpler way to understand ??

 

[horace1]

if the pin is an ADC input you can use the same pin for voltage and frequency (clearly you cannot use the same pin as an ADC input and "interupt on change")
you can read ADC sample into a buffer and calculate the voltage (average, RMS, ?) and frequency
if the signal is fairly clean and you don't want harmonics you can look for crossing a set voltage (looking for rising and falling edges with Hysteresis in case of noise) and using a timer determine the period of the signal and hence its frequency