This document summarizes a closed loop control system using a PID controller based on an ATmega8535 microcontroller. The system takes an analog input from ADC channel 0 pin 40, and outputs a PWM signal on PWM1a pin 19. It describes initializing variables, configuring the ADC and PWM, setting control parameters like proportional, integral and derivative gains, and implementing a PID control algorithm in a loop to regulate the system based on feedback.

1. '=====================================================
' Sistim kontrol closed loop dengan pengaturan PID
' berbasis mikrokontroller ATmega8535
' input analog <- ADC kanal 0 pin 40
138
' output PWM -> PWM1a pin 19
'=====================================================
'pada saat simulasi instruksi wait tidak berpengaruh
$sim
'ic mikrokontroller yang dipergunakan
$regfile "m8535.dat"
'kristal yang dipasang 12 MHz.
$crystal = 12000000
'setting baud rate
$baud = 9600
'deklarasi varibel
Dim W As Word , Ts As Single
Dim Dv As Single , Av As Single , E As Single
Dim Kp As Single , Ki As Single , Kd As Single
Dim Ekp As Single , Eki As Single , Ekd As Single
Dim Outp As Single , Outi As Single , Outd As Single
Dim Ekiold As Single , Ekdold As Single
Dim Outiold As Single , Outdold As Single
Dim Outpid As Single
Dim Outpwm As Byte
'konfigurasi ADC
Config Adc = Single , Prescaler = Auto
Start Adc

2. 'konfigurasi PWM
Config Timer1 = Pwm , Pwm = 8 , Compare A Pwm = Clear Down , Compare B
Pwm = Clear Down , Prescale = 1
139
'inisialisasi nilai awal
Ekiold = 0
Outiold = 0
Ekdold = 0
Outdold = 0
'setting point, desired value
Dv = 2
'setting paremeter kontrol
Kp = 1
Ki = 1
Kd = 0
'setting time sampling (Ts) 1 detik
Ts = 1
'algoritma kontrol PID
‘==============================================================
Do
W = Getadc(0)
Av = W * 5
Av = Av / 1023
E = Dv - Av
Outp = E * Kp
Eki = E * Ki
Eki = Eki * Ts
Outi = Outiold + Ekiold
Ekd = E * Kd

3. Outd = Ekd - Ekdold
Outd = Outd / Ts
Outpid = Outp + Outi
Outpid = Outpid + Outd
If Outpid > 255 Then Outpid = 255
If Outpid < 0 Then Outpid = 0
140
Outpwm = Int(outpid)
Pwm1a = Outpwm
'mengirim data ke komputer melalui RS232
Print Dv ; Chr(9) ; Av ; Chr(9) ; E ; Chr(9) ; Outpwm
Ekiold = Eki
Outiold = Outi
Ekdold = Ekd
Outdold = Outd
Wait Ts
Loop
End