controling arduino mega2560

I am trying to generate a square wave in pin 'A0' of arduino MEGA 2560 with frequency of F=100HZ

( in order to control a stepper motor in x axis using the RAMPS shield)

I tried simply by turning the pin ON and OFF and using pause(1/2*F) between and the max frequency I get is 5HZ.

my code:

a=arduino();

f=100;

PIN1='A0';

configurePin(a,PIN1,'DigitalOutput');

while true

WriteDigitalPin(a,PIN1,1);

pause(1/f*2);

WriteDigitalPin(a,PIN1,0);

pause(1/f*2)

end

can you offer a way to achieve higher frequencies?

Thanks!

Answer 1

[Sanju]

Hi lital,

I understand that you want to achieve a higher frequency using Arduino MEGA 2560.

To achieve higher frequencies, optimize your code to minimize the time overhead caused by the ‘pause()’ function and other loop operations. Consider utilizing the ‘writePWMVoltage’ function instead of ‘writeDigitalPin’.

‘writePWMVoltage’ is a MATLAB function that is used to set the voltage of a ‘PWM’ pin on an Arduino board. PWM pins allow you to generate analog-like signals by rapidly switching the pin between high and low states at a specific frequency. The ‘writePWMVoltage’ function takes two arguments, the Arduino object and the pin number, and sets the voltage of the specified pin.

Here's a modified version of your code you may refer to,

a = arduino('COM3', 'Mega2560'); 
f = 100; 
PIN1 = 'D9'; 
configurePin(a, PIN1, 'PWM');  

% Calculate the time period in microseconds 
T = 1 / f; 

while true 
    writePWMVoltage(a, PIN1, 0); % Set the voltage to 0V 
    pause(T / 2); % Wait for half a period 
    writePWMVoltage(a, PIN1, 5); % Set the voltage to 5V 
    pause(T / 2); % Wait for half a period 
end 

In the above code,

I have changed the pin to a digital pin (D9), as it has better performance compared to analog pins.

I have directly calculated the time period (T) in microseconds and use it to control the timing of the square wave. By avoiding unnecessary calculations and function calls within the loop, we reduce the overhead and increase the achievable frequency.

This loop generates a square wave with a 50% duty cycle at a frequency of 100 Hz on pin D9 of the Arduino board, causing the connected hardware to oscillate between 0V and 5V.

You can also refer to the following documentation links for further information,

https://www.mathworks.com/help/supportpkg/arduinoio/ref/writepwmvoltage.html

https://www.mathworks.com/hardware-support/arduino.html

https://www.bing.com/videos/search?q=getting+started+with+arduino+matlab&qpvt=getting+started+with+arduino+matlab&FORM=VDRE

Hope this helps!

[lital]

Thanks Sanju,

But because I'm using the RAMPS shield I need to generate the specific pin A0. so i can't use the writePWMVoltage() as you suggested.

[Sanju]

Hey lital,

In this scenario, you might consider persisting with the writeDigitalPin function. However, it could be beneficial to compute the time period outside the loop and verify the resulting frequency. Alternatively, employing the delayMicroseconds function instead of pause can offer more precise control over timings.

Please note that the maximum achievable frequency is still limited by the processing speed of the Arduino and the overhead of executing the loop code.