Kurnia,

Two techniques are discussed one technique uses PWM into an integrating cap to produce variable voltage levels which are compared against the unknown voltage the result of the compare being available in p3.6.

The second technique uses an 8 bit DAC to generate the voltage to which the unknown voltage is compared.

Either way you test the unknown signal against binary fractional voltages that you generate. Start with an 8 bit "fractional voltage register" = 0. Output 1/2 scale is this more or less than the unknown voltage? If less Reset the msb in your fractional voltage register. If more you Set the msb.

Output the fractional voltage register + D6 =1. Is this more or less? Perform as above until all 8 bits have been tested.

If you use PWM your fractional voltage register is used to set the waveform 1/2 cycle period which integrates across the R/C as a variable voltage.

regards,
p