PID

PID controller for Atmega32

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Developers

• Omid RostamAbadi
• Sadra Sabouri

Main Process

PID controller details have been came bellow:

• Changeable coefficients for P, I and D

• Each coefficient should be edited by user between 0 and 16

• Working point can be set by user from 0 to 2.56 Volts.

• Sampling time should be 20ms

• Input signal has a amplitude between 0 and 2.56 Volts.

• Output is a 8 bit number on Port C showing a value between 0 - 2.56 Volts

• When Atmega32 is not working on PID coefficients it work as a timer and increase a value which is on 200H to 205H of RAM.

• When system starts it'll be reset and counter will become 0

• After 16 mins 5 byte of counter will be sent to Port D in a little-endian mode.

P, I and D coefficients and set point are loaded into ROM by user and AVR will load them into it's memory after execution.

Value	Place on ROM
P	20
I	21
D	22
Set Point	23

Then after each iteration (taken each 20ms) the error will be calculated from bellow equation:

error = error - pv;

(that pv stands for present value of the system)

Then new output will be calculated by bellow equation:

output = k_p * error + k_i * integral / SCALE + k_d * derivative * SCALE;

(in that terms are representing P, I and D segments respectively)

The output value will be shown on a 10 pin compact LED (as there is in picture).

Also there is a timer which uses AVR's timer as a interrupt source and counts each second saving its content in bellow RAM bytes:

Value	Place on ROM
Seconds	0x200
Minute	0x201
Hour	0x202
Day	0x203
Week	0x204
Month	0x205

These values will be updated in each second and there will be sent to PORTD as a big-endian manner after each 16 minutes.

Develop

You should use Proteus 8 and WinAVR compiler so that you can open main.c code in Source Code tab by right click on ATMEGA32 and click on Edit Source Code.

Files

This repository contain multiple files which is described here in details:

• test.c A C program for first test of the PID controller and check if the logic is right. To compile it you can simply run:

$ gcc test.c

• PID.pdsprj Main project file which contains both schematic and codes needed for project.

Note: You should use Proteus 8.9 or bellow and WinAVR for compile.