From 79563b21d67ff2b5e68dd8850f95d1dab23d4559 Mon Sep 17 00:00:00 2001
From: hakan-demirli <78746991+hakan-demirli@users.noreply.github.com>
Date: Mon, 8 Mar 2021 00:55:32 +0300
Subject: [PATCH] Update README.md

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 # PID-FPGA
 PID controller on an FPGA with custom RS232 addressing protocol.
+
+![alt text](https://github.com/hakan-demirli/PID-FPGA/blob/main/BirdsEyeView.png?raw=true)
+
+To capture the motor's precise behavior, data sampling speed is synchronized with the TX module. But unfortunately, most of the serial port terminal programs, including [Terminal v1.9b by Br@y++](https://www.narom.no/undervisningsressurser/the-cansat-book/the-primary-mission/using-the-radio/terminal-program/) and [Termite](https://www.compuphase.com/software_termite.htm), failed to keep up with this speed. [HTerm](http://der-hammer.info/pages/terminal.html) was the only one I found that operated with no problems.
+
+# Communication Protocol
+RS232:
+ * Data Bits: 8
+ * Stop Bits: 1
+ * Parity: None
+ * Baud Rate 115200  
+ 
+The instructions are 64-bit. The first and the last 8 bits are must be AA and BB, respectively, to ensure package integrity.  
+|AA|8bit address|4 bit useless|36Bit data|BB|
+The Numbers are fixed point 36 bit signed |1bit|26bit|9bit|  
+ * Accessing to address zero sets the global reset to one.
+ * Address one is KP
+ * Address two is KD
+ * Address three is KI
+ * Accessing to address zero sets the global reset to zero.  
+Examples:  
+AA00xxxxxxxxxxBB // reset = 1  
+AA010000000500BB // KP = 2.5  
+AA020000000500BB // KD = 2.5  
+AA030000000500BB // KI = 2.5  
+AA0D000000FFFFBB // reset = 0  
+
+# Hardware
+ * Alter DE2 FPGA: EP2C35F672C6
+ * DC Motor: (unknown)
+ * Encoder: ARC S 050
+ * Motor Driver: Custom  
+ ![alt text](https://github.com/hakan-demirli/PID-FPGA/blob/main/HARDWARE.jpg?raw=true)
+# Verification of Design
+ * Quartus project is verified by testbenches.
+ * Overall project verified by oscilloscope measurements of the frequency of the encoder signals.
+ The motor speed is 14.15708 RPS (7078.54/500). Which is quite close to the desired speed: 14 RPS.  
+ ![alt text](https://github.com/hakan-demirli/PID-FPGA/blob/main/14RPS.png?raw=true)  
+ * Motors response to disturbances under PID control:  
+  ![alt text](https://github.com/hakan-demirli/PID-FPGA/blob/main/Disturbance.jpg?raw=true)  
+# Possible Design Improvements and Current Flaws
+ * Rotatory Encoder creates 500 pulses for every rotation. But, the calculations are done by dividing the pulse count by 512 in order to avoid a separate division circuit.
+ * There is a bug with the multiplication circuit. The numbers are ~0.8% off.
+ * In my hardware setup, the DC motor and the Encoder are connected via a custom imperfect shaft that causes a sinusoidal noise on the speed values.
+ * After the final debugging, I forgot to change the source of the desired speed from switches to RS232. So, you have to enter the desired speed from switches.
+ * Current KP, KD, and KI values are quite low. It takes a couple of seconds for the motor to reach its final value. 
+ * There is no integral windup protection.
+ * I am a sophomore student without any Control background so that is the best I can do in a week.
+