i want to read the output frequency of my oscillator ( 50 - 150 MHz ) with arduino , the oscillator output is a sinewave signal . i used a frequency divider 1:64 MB504 , to reduce the frequency so that i can read it with arduino ( 8 MHZ) . i found many method to read frequency with arduino ( pulsln , freqcount ..) . the divider output voltage is 1.6 peak to peak . i need to addapt the voltage between 0 and 5 v . can anyone help me please ??

 

I don't see why you need to change 1.6 Vpp to 0-5 V range.

You want frequency. Your ADC can detect positive peaks. Take two positive peaks, ignore negative portion of the signal, find time between the two positive peaks, that is the period of the signal. 1/period=frequency

 

i want to read the output frequency of my oscillator ( 50 - 150 MHz ) with arduino , the oscillator output is a sinewave signal . i used a frequency divider 1:64 MB504 , to reduce the frequency so that i can read it with arduino ( 8 MHZ) . i found many method to read frequency with arduino ( pulsln , freqcount ..) . the divider output voltage is 1.6 peak to peak . i need to addapt the voltage between 0 and 5 v . can anyone help me please ??

On the simulation output voltage is from -0,2 to 3,6 volts and atmega328p counter input can detect it as is when the supply is 5 volts. Input threshold is about 3 volts.

 

i found method using analog comparator : https://arduino.stackexchange.com/questions/21157/arduino-read-frequency-of-input-from-audio-jack
Can I use this comparateur without the voltage divider ? and use the same code ???

volatilebool counting;volatileunsignedlong count;

ISR (ANALOG_COMP_vect){if(counting)
count++;}

void setup (){Serial.begin(115200);Serial.println ("Started.");
ADCSRB =0;// (Disable) ACME: Analog Comparator Multiplexer Enable
ACSR = bit (ACI)// (Clear) Analog Comparator Interrupt Flag| bit (ACIE)// Analog Comparator Interrupt Enable| bit (ACIS1);// ACIS1, ACIS0: Analog Comparator Interrupt Mode Select (trigger on falling edge)}// end of setup

unsignedlong startTime;

void loop (){

if(!counting){
startTime = micros ();
count =0;
counting =true;}else{// is a second up? (1000000 microseconds)if(micros ()- startTime >=1000000){
counting =false;Serial.print(count);Serial.println (F(" Hz."));}// end of a second being up

}// end of if

}// end of loop

 

I don't see why you need to change 1.6 Vpp to 0-5 V range.

You want frequency. Your ADC can detect positive peaks. Take two positive peaks, ignore negative portion of the signal, find time between the two positive peaks, that is the period of the signal. 1/period=frequency

Can you explain more how can I do that with an example or schematic ?

 

Can you explain more how can I do that with an example or schematic ?

We don't care about anything below zero because we don't need it. Your ADC is set to read the values above zero so you should not have any trouble reading the positive peaks.

Just figure out the time between the two peaks.

 

ok , code for ADC counting plz ? and at which pin the device will be connected ?

 

I think he means the analog comparator can be used to drive the on-chip counter. One comparator input can be connected to the output of your counter and the other can use the internal 1.1 volt bandgap reference.

 

i found this : http://interface.khm.de/index.php/lab/interfaces-advanced/arduino-frequency-counter-library/ using frequency counter count up to 8 MHz , or the output divider frequency is ( 150 / 64 = 2.34 MHz ) , then converting my sinewave to square wave using the trigger shmitt 74HC14N and connect it to te digital pin 5 . i think i don't need the amplification !!