Hello.
I am trying to create a PC fan controller for which the optimal frequency is ~25 kHz. I have a Seeeduino Lotus v1.0 plugged into I2C motor driver v1.3b. I am able to change my fan speed easily, but my frequency is way too low. With an oscilloscope I measure my frequency at only 30.12 Hz. I have tried changing PWMFrequencySet from 0x84 to 0x01 and 0xFF. I’ve also tried changing “Frequence” from 0x00 to 0xFF. I am seeing no change in frequency at all. Am I calling the function incorrectly? Please help.
This is my code:
[code]#include <Wire.h>
#define MotorSpeedSet 0x82
#define PWMFrequenceSet 0x01 //default 0x84
#define DirectionSet 0xaa
#define MotorSetA 0xa1
#define MotorSetB 0xa5
#define Nothing 0x01
#define EnableStepper 0x1a
#define UnenableStepper 0x1b
#define Stepernu 0x1c
#define I2CMotorDriverAdd 0x0f // Set the address of the I2CMotorDriver
void setup() {
Wire.begin(); // join i2c bus (address optional for master)
delayMicroseconds(10000);
Serial.begin(9600);
Serial.println(“setup begin”);
}
void loop() {
// the following code sent commands to motor driver to drive DC motor
while(1) {
Serial.println(“sent DC speed 100”);
delay(50);
MotorSpeedSetAB(50,100);//defines the speed of motor 1 and motor 2;
delay(50); //this delay needed
MotorDirectionSet(0b1010); //"0b1010" defines the output polarity, "10" means the M+ is "positive" while the M- is "negtive"
// make sure M+ and M- is different polatity when driving DC motors.
delay(50);
MotorPWMFrequenceSet(0x01);
delay(5000);
//MotorDirectionSet(0b0101); //0b0101 Rotating in the opposite direction
delay(5000);
}
}
//////////////////////////////////////////////////////////////////////
//Function to set the 2 DC motor speed
//motorSpeedA : the DC motor A speed; should be 0~100;
//motorSpeedB: the DC motor B speed; should be 0~100;
void MotorSpeedSetAB(unsigned char MotorSpeedA , unsigned char MotorSpeedB) {
MotorSpeedA=map(MotorSpeedA,0,100,0,255);
MotorSpeedB=map(MotorSpeedB,0,100,0,255);
Wire.beginTransmission(I2CMotorDriverAdd); // transmit to device I2CMotorDriverAdd
Wire.write(MotorSpeedSet); // set pwm header
Wire.write(MotorSpeedA); // send pwma
Wire.write(MotorSpeedB); // send pwmb
Wire.endTransmission(); // stop transmitting
}
//set the direction of DC motor.
void MotorDirectionSet(unsigned char Direction) { // Adjust the direction of the motors 0b0000 I4 I3 I2 I1
Wire.beginTransmission(I2CMotorDriverAdd); // transmit to device I2CMotorDriverAdd
Wire.write(DirectionSet); // Direction control header
Wire.write(Direction); // send direction control information
Wire.write(Nothing); // need to send this byte as the third byte(no meaning)
Wire.endTransmission(); // stop transmitting
}
//set the prescale frequency of PWM, 0x03 default;
void MotorPWMFrequenceSet(unsigned char Frequence) {
Wire.beginTransmission(I2CMotorDriverAdd); // transmit to device I2CMotorDriverAdd
Wire.write(PWMFrequenceSet); // set frequence header
Wire.write(Frequence); // send frequence
Wire.write(Nothing); // need to send this byte as the third byte(no meaning)
Wire.endTransmission(); // stop transmitting
}[/code]
