State functions of the following pins of IC555.
1) Control: - The dc Voltage at this pin is 2/3 Vcc. An external voltage applied to this changes threshold as well as trigger voltage to obtain pulse width modulated output.
2) Trigger: - The output of the timer depends on the amplitude of the pulse applied to this pin. Output is low of the voltage at this pin is greater than 2/3 Vcc . When the voltage goes below 1/3 Vcc, output of the timer goes high.