PWM/Analog pin vs Digtal pin

[chinlin0924]

Hi all,

I am new to electronics. I purchased a arduno board, but I am a bit confused on the term definition.
I saw some pins are for PWM, or digital pins , SDA/SCL pins.
1. Does that mean PWM pins also works for PWM, can it be used for digital output?
2. Can digital pin be used for output PWM?
3. Can I use other pins for SDA/SCL pins?

If above questions are all yes, then why not define them as GPIO pin?
Sometimes, the terms seems give me confuse, and let us think it only works for that purpose.

Thanks

 

[hamidmoallemi]

in microcontrollers some of the pins have other functionalities than standard I/O pin , such as PWM , Serial communication , analog inputs , JTAG etc.
their function is selectable in software , there are some control registers that determine weather these pins to be an I/O or not.
for example you can use a PWM pin as PWM output or a standard I/O and do this thorough softwware , but you cant use a simple I/O for other purpose like SCL etc.

 

[chinlin0924]

in microcontrollers some of the pins have other functionalities than standard I/O pin , such as PWM , Serial communication , analog inputs , JTAG etc.
their function is selectable in software , there are some control registers that determine weather these pins to be an I/O or not.
for example you can use a PWM pin as PWM output or a standard I/O and do this thorough softwware , but you cant use a simple I/O for other purpose like SCL etc.

Can't I implement SCL with normal IO and timer to generate the signal wave form like SCL needs?

 

[hamidmoallemi]

you can do it , but you must write program to do that and it means using CPU , the main advantage of peripherals such as pwm generator is that they don't use cpu to do their job, you should just set their control registers