Problems creating 10Hz pulse wave

Question

I'm trying to make a 10Hz pulse wave output at Arduino's pin 9 by using the following code I wrote:

#define F_CPU 16000000UL
#include <avr/io.h> //Defines pins, ports, etc.
#include <util/delay.h>
int main(void)
{
 DDRB |= (1<<DDD1); //Does this set port B pin 1 and is this pin 9 in UNO board?
 PORTB |= (1<<PORTB1);
 while(1){
 PORTB |= ~(1<<PORTB1);
 _delay_ms(100);
 PORTB |= (1<<PORTB1);
 }
}

I use Atmel Studio to uplaad the code and it works fine with other codes. But for some reason this code doesn't work. What can be the problem here?

Still doesnt work edit:

#define F_CPU 16000000UL
#include <avr/io.h> //Defines pins, ports, etc.
#include <util/delay.h>
int main(void)
{
 DDRB |= (1<<DDD1);
 PORTB |= (1<<PORTB1);
 while(1){
 PORTB &= ~(1<<PORTB1);
 _delay_ms(100);
 PORTB |= (1<<PORTB1);
 }
}

Answer 1

You have your whole 100ms wait time while the pin is low. You need half of it while low, half while high.

while(1){
 PORTB &= ~(1<<PORTB1);
 _delay_ms(50);
 PORTB |= (1<<PORTB1);
 _delay_ms(50); // You need a delay here too.
}

• floppy380: oh without the second delay it just jumps to low again. i see thanks. just curious is this a good way to obtain a very precise pulse frequency? i mean by using delay function as i did? or interrupts required? im trying to build a as precise as possible simple pulse generator.
• KIIV: @doncarlos no kidding, I was telling to you for a while!
• KIIV: @doncarlos and no, this is horrible way to do frequency generator. Use Timers and it's waveform generator modes instead.

Answer 2

Your code doesn't clear anything.

 PORTB |= ~(1<<PORTB1); // set everything except PORTB1 pin
 _delay_ms(100);
 PORTB |= (1<<PORTB1); // set PORTB1 pin

And recommended tutorial: Bit manipulation (AKA "Programming 101") from the AVRFreaks.net

BTW: next issue might be "the pulse is way too fast so it seems there is none"

Try this:

while(1) {
 PINB = _BV(PINB1); // toggle pin
 _delay_ms(50);
}

• floppy380: Doesn't PORTB |= ~(1<<PORTB1); set PORTB1 pin to zero?
• KIIV: No, pipe | is logic OR, that means whenever is corresponding bit logic one, result is logic one
• floppy380: pulse is not fast and set to 10Hz _delay_ms(100). And I check with a scope. Theres nothing still
• KIIV: @doncarlos Well - there is clear bit, wait for 100ms, set bit ... and repeat.. that pause between setting and resetting bit might be even less than 200ns

Answer 3

 PORTB |= ~(1<<PORTB1);

change it to:

 PORTB &= ~(1<<PORTB1);

if you want to clear PB1.

• floppy380: I made that change but still doesnt work. Please see my edit.
• KIIV: @doncarlos see my "BTW" edit :D