Hello, I'm new to Arduino, and I want to build a frequency counter to read the 5V 50% duty cycle at frequencies ranging from 1Hz to 500Hz. After completing my literature review, I found a decent program that fulfills my requirements. So, I am using a signal generator to produce the square wave and a Nano RP2040 to do the job. However, when I try to increase the refresh rate to 100ms, the reading accuracy is very poor. Below is the Arduino program. Could anyone please suggest a solution to increase the refresh rate? Thank you.
//freq counter reads sine, square, and triangle waves
unsigned long currentMillis; // current time in milliseconds
unsigned long lastMillis; // time of the last reading in milliseconds
unsigned long duration; // duration between readings in milliseconds
int pulseHigh; // flag for detecting a high pulse
int pulseLow; // flag for detecting a low pulse
long halfCycles; // count of half cycles
long cycles; // count of full cycles
int in = LOW; // input pin state
void setup () {
pinMode(3, INPUT); // set pin 3 as input
Serial.begin(9600); // initialize serial communication
Serial.println("The frequency is displayed in Hertz"); // print message to serial monitor
}
void loop () {
lastMillis = millis(); // get the current time
// Read input and measure pulse duration
do {
in = digitalRead(3); // read the state of pin 3
currentMillis = millis(); // get the current time
duration = currentMillis - lastMillis; // calculate the duration since the last reading
// Check if the input is high
if (in == HIGH) {
pulseHigh = 1; // set the high pulse flag
}
// Check if the input is low
if (in == LOW) {
pulseLow = 1; // set the low pulse flag
}
// Check if both high and low pulses occurred
if (pulseHigh == 1 && pulseLow == 1) {
halfCycles = halfCycles + 1; // increment the half cycle count
pulseHigh = 0; // reset the high pulse flag
pulseLow = 0; // reset the low pulse flag
}
} while (duration < 1000); // repeat until 1 second has elapsed (looking for cycles per second)
cycles = halfCycles / 2; // divide by two, as there are two half cycles in a full cycle
Serial.println(cycles); // print the frequency in Hertz
cycles = 0; // reset the cycle count
halfCycles = 0; // reset the half cycle count
delay(1000); // delay for 1 second before taking the next reading
}
Where in your program do you set the refresh rate?
Why do you want it faster than 100ms?
That is about as fast your eyes can see... so you will not win much...
The program wasn't made by me. I expected that changing the "duration<1000" and "delay(1000)" would increase the refresh rate; however, it seems that it does not...
I also don't understand why you are need so quick to refresh. Have you tried increasing the speed on the serial communication though? For example, instead of 9600 it is 115200 or even more.
I want to make a digital speedometer for my motorcycle. The MCU will output the engine revolution in terms of frequency, within a range around the maximum frequency of 500Hz, which equals 15,000rpm. I am using the Nano RP2040 to project the frequency onto an LCD display. However, a refresh rate of 1 second is quite low for my application.
I have tried increasing the baud rate, but it had no effect. Therefore, I am seeking advice on how to increase the refresh rate.
