Always HIGHT line on Oscilloscope when UNO's Fast PWM TOP ICR1
You might want to set the TCCR1A and TCCR1B registers to 0 before your code as the Arduino library sets the WGM10 bit. Or change the first |= to a =. By leaving the WGM10 bit set, you get fast PWM mode, with TOP set to OCR1A. Combined with your other code, this would result in both pins having a 100% duty cycle.
So use
TCCR1A=(0&lt;&lt;WGM10)|(1&lt;&lt;WGM11);
TCCR1B=(1&lt;&lt;WGM13)|(1&lt;&lt;WGM12);

or
TCCR1A=0;
TCCR1B=0;
TCCR1A|=(0&lt;&lt;WGM10)|(1&lt;&lt;WGM11);
TCCR1B|=(1&lt;&lt;WGM13)|(1&lt;&lt;WGM12);

Other than that, you code looks fine, and should give you a 800Hz signal.
PS &quot;I assumed that my UNO works on 1 MHz&quot;; no, the UNO runs at 16Mhz.