I'm currently making a project using the ATMega328p to read i2c signals from a sensor, and also to use the analog output to communicate with another microncontroller.
It's going to be soldered to a pcb which is going to be developed by me, and it should be as small as possible, so i thought about using the internal 8MHz clock instead of using the very commom 16Mhz Crystal Oscillator.
Is it possible to have reliable i2c and analog output communication without the crystal? Is that recommended?
Sure you can. But your "analog communication" is something I've never seen done, so that is questionable. What analog output are you referring to? The basic Arduino has no real analog outputs, just PWM.
I'm planning to use the PWM just as you told, sorry if i was not very specific. Will the PWM communication also be reliable and precise without the crystal then?
Smug:
Will the PWM communication also be reliable and precise without the crystal then?
What PWM communication do you mean? You talk as if it's something common but it isn't. So you have to explain what you are doing, in a lot more detail... you do know that PWM can not be read directly with an analog input (ADC), right?
I2C is not at all frequency critical, certainly not slowing it down; it is self-clocked. That is why you can emulate it in software perfectly.
Similarly, PWM as such is not frequency critical. If you are using it as a form of pulse width communication, as long as the recipient is timing both the HIGH and the LOW parts and using the ratio, there will be no problem.
Anything besides steady DC from an output pin, whether it's servo signals, mark / space from a uart or a square wave pulse train is called "PWM" by noobs. How do you you plan to transmit intelligence with PWM?
OOPS: Forgot Morse code.
