PWM pins not working

Projects Programming
1

I have started to make an engine controller, but at the moment I am facing some PWM problems.
Board : ARDUINO UNO
Inputs:
Signal from potentiometer ( throttle )
3 momentary pushbuttons. ( gear position )

Outputs:
1 servo for throttle
1 servo for gear position
3 leds for indication of gear position.

I have a suspicion that the servo.h are interference with the normal use of PWM pins (analogWrite). In the program only pin 11 seems to works as I expected. Pin 9 and 10 are just flickering. When I remove all program there are belonging to the servo.h the IF ELSE statements are working as expected. Therefor I also know that my hardware is working well. It must be a software problem (a bug)

Have any of you had similar problems?

Is there a known limitation of servo.h I don’t know about?

Have I made any obviously mistakes ?

Best regards

Søren

#include <Servo.h>
int gearPos = 50;
const int pinfrem = 2;
const int pinneu = 3;
const int pinbak = 4;

int val1;
int val2;
int val3;

int brightness_low;
int brightness_high;


Servo myservo_gear;
Servo myservo_gas;

//int ledpinfrem = 9;
//int ledpinneu = 10;
//int ledpinbak = 11;

int potpin = 0;  // analog pin used to connect the potentiometer
int val;    // variable to read the value from the analog pin


void setup() {
 // Serial.begin(9600);
  
myservo_gear.attach(6);
myservo_gas.attach(5);


pinMode(pinfrem,INPUT);
pinMode(pinneu,INPUT);
pinMode(pinbak,INPUT);

//pinMode(9,OUTPUT);
//pinMode(10,OUTPUT);
//pinMode(11,OUTPUT);
}

void loop() {

val = analogRead(potpin);            // reads the value of the potentiometer (value between 0 and 1023)
val = map(val, 0, 1023, 30, 140 );
  
val1 = digitalRead(pinfrem);
val2 = digitalRead(pinneu);
val3 = digitalRead(pinbak);

brightness_high = 250;
brightness_low = 2;

if      (val1 == HIGH)  {gearPos = 50 ;analogWrite(9,  brightness_high);analogWrite(10, brightness_low);analogWrite(11, brightness_low);} 
else if (val2 == HIGH)  {gearPos = 90 ;analogWrite(9, brightness_low);analogWrite(10, brightness_high);analogWrite(11,  brightness_low);}   
else if (val3 == HIGH)  {gearPos = 130;analogWrite(9, brightness_low);analogWrite(10, brightness_low);analogWrite(11,  brightness_high);}

brightness_high = 250;
brightness_low = 2;

delay(2);

myservo_gear.write(gearPos);   
myservo_gas.write(val); 
}
2

soerentrankjaer:
Have I made any obviously mistakes ?

Yep... you didn't RTFM... para 2, line 2

3

Thanks JimboZA !

Haven´t read that part before. Fits perfectly to my problem.

"The Servo library supports up to 12 motors on most Arduino boards and 48 on the Arduino Mega. On boards other than the Mega, use of the library disables analogWrite() (PWM) functionality on pins 9 and 10, whether or not there is a Servo on those pins. On the Mega, up to 12 servos can be used without interfering with PWM functionality; use of 12 to 23 motors will disable PWM on pins 11 and 12. "

best regards

Søren