The Engineering Projects

.the PWM signal from the pro mini IC ATMEGA-328 has to send to servo motor through serial communication.Ihvae two questions .
1)how PWM signal value is 0-255 ?if it is that,that data transmitted is 8-bit so it makes 256 combinations.it is alright.i agree!! but why when we connect the serial port we have to use only 1 pin of IC to transmit PWM signal to the servo ? is that 1 pin of the IC transmits 8 bit data??

2)how should i connect the servo motor to the IC.which pin should be connected so that serial PWM signal goes ..i mean which pin of IC has to be connected to which serial port pin for PWM transmission and why .

3)any good programming book link for coding pro mini in keil or matlab

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