PWM 10Hz Converted to 50Hz and mirroring/opposite duty cycle, give or take

Other Hardware Sensors
1

Hello all.
I have heard of Ardunos in conversation and seen them in actual homemade project development, however, at that time I could not grasp the concept of typing lines of code and having something act upon it. Nothing has changed since then and I still have a hard time with things like this. I am VERY new to Arduno, hands-on.

I have a modified automobile that is having a cooling miscalculation, leading to overheating under very high loads. This automobile has a PRIMARY brushless electric suction fan with its own built-in BLDC motor controller that works very well. And I have found an additional/SECONDARY BLDC electric suction fan with its own built-in BLDC motor controller that ALSO works very well, BUT it came out of a completely different automobile brand. And this SECONDARY fan operates at a different way than the primary one.

The PRIMARY BLDC fan operates at a PWM command from the engine control unit that is at 10hz, and when the duty is at ;
90% fan is maximum speed.
50% fan is medium speed.
10% fan is off.

This SECONDARY BLDC fan operates at a PWM command from the engine control unit that is at 50hz, and when the duty is at ;
90% fan is off.
50% fan is medium speed.
10% fan is maximum speed.

I want something to piggyback off the line to the primary fan so I can get the secondary fan working automatically without the use of an external signal generator, with a manual human user interface. Which is/was the original idea.
I need both fans to run at roughly the same speed VIA PWM duty, give or take, but I may want some customizability, more so to have the secondary fan come on earlier.

If anyone believes that an Arduino is or is not the best fit for me, let me know. Thank you. Any help is much appreciated.

2

Yes, an Arduino could do this.

It will be lots of new things for you to learn. I hope you are looking for a challenge!

One of the best things about Arduino is this forum. You can get unlimited help from expert arduino users here. But to be given that help, you will need to show that you are willing to learn and to try. Don't expect the forum to do everything for you, for example writing all the code for you.

That's an interesting one. How can the secondary fan know in advance that the primary fan is going to come on before it happens?

3

PauRB; I appreciate the reply.
I understand knowledge is not given but learned. I want to learn. I am a slow learner. I have time.
About the secondary fan coming on earlier; Like say primary fan has a duty of 15% then secondary fan is 20%, If Primary fan is anything above 80% make secondary fan 100%, so to speak.

This forum does seem very inviting to the whole program here. :slight_smile:

4

The forum often responds very differently to newcomers with different, and sometimes unreasonable preconceptions of what the forum is about. The forum has a reputation for being unfriendly and unwelcoming to those types of newcomers. But you seem to be taking the right attitude.

Anyway, here are my first thoughts about your project.

Automobiles are harsh environments for electronics and microprocessors, and Arduino is no exception. Steps will need to be taken to ensure the Arduino has a suitable and stable power supply and it's inputs and outputs are protected from high voltages and interference. But initially I guess you will be building and testing a prototype on the bench, so those concerns can be addressed a little later.

Don't rush out and buy an Uno or Mega because that's what everyone thinks should be their first Arduino. In my opinion you will be much better off with a classic Nano V3 because it's breadboard and stripboard/veroboard compatible, which is what you need for building your prototype. And get a decent sized breadboard to go with it, not some tiny thing with no room to work on.

5

Here's a crude duty cycle sketch I wrote once upon a time for UNO / Nano. :grin:

/*
 * In Serial Monitor, type h for cycle time in Hz, then number,
 *  EXAMPLE, h20. then p for percent duty cycle,
 *  EXAMPLE, p5, or both on 1 line,
 *  EXAMPLE, h10,p30, onboard LED will blink.
 */
 unsigned long cycleStart,
              onTime,              
              cycleTime,
              hz;
int val;              
const byte powerPin = LED_BUILTIN;
byte percent = 50;
void setup()
{
  Serial.begin(9600);
  Serial.println(" Hz = 5  Duty Cycle = 50%");
  hz = 5;
  cycleTime = 1000000UL / hz;
  onTime = cycleTime / 2;  
  pinMode(powerPin,OUTPUT);
}
void loop()
{
  bitWrite(PORTB,5,micros() - cycleStart < onTime);  
  if(micros() - cycleStart > cycleTime)
    cycleStart += cycleTime;
  // if there's any serial available, read it:
  if(Serial.available() > 0)
  {
     val = Serial.read();
    if(val == 'h' || val == 'H')
      hz = Serial.parseInt();
    else if(val == 'p' || val == 'P')
    {
      percent = Serial.parseInt();   
    }
    else
      while(Serial.available() > 0)
        Serial.read();  
    cycleTime = 1000000UL / hz;
    percent = constrain(percent, 0, 100);
    onTime = cycleTime * 0.01 * percent;
    cycleStart = micros();
    Serial.print(" Hz = ");
    
    Serial.print(hz);
    Serial.print("  Duty Cycle = ");
    Serial.print(percent);
    Serial.println("%");
  }
}

Better to use hardware timers though.

6

As a start I'd be inclined to build a simple controller with a 555 timer and a temperature sensor on the coolant hose.

7

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