PWM glitches, Analog Write

Hi,

Playing around with AnalogWrite and my scope:

This little script toggles between two duty cycles:

const int analogOutPin = 9;

void setup() {
  pinMode (analogOutPin,OUTPUT);
}

void loop() {
  analogWrite(analogOutPin, 100);
  delay(15);
  analogWrite(analogOutPin, 150);
  delay(15);
  }  

below is how this looks on the scope, blue direct, yellow with a simple

R-C lowpass.

every now and then, when changing duty cycle, I get an extra-long pulse.

I am using the G2553 on the launchpad, with xtal.

I have seen on this forum that calling AnalogWrite when NOT changing the duty cycle should be avoided.

But I DO sometimes want to change the duty cycle  ;-)

Tried the same on an Arduino Uno, no problem there, smooth transitions.

any suggestions?

maelli01