Started lab notes for labs 3 and 4.

.gitignore

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 **/*.synctex.gz
 **/*.aux
 **/.vscode
+**/_minted*

labnotes/Lab 3 and 4.tex

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+\documentclass[letterpaper]{article}
+\author{Jonathan Chan (15354146)}
+\title{PHYS 319\\Labs 3 and 4 Notes}
+
+\usepackage{fullpage}
+\usepackage{minted}
+%{\renewcommand\fcolorbox[4][]{\textcolor{red}{\strut#4}}
+
+\begin{document}
+	\maketitle
+	
+	To compile the C programs to .asm and .elf, I've modified my Makefile as below.
+	\begin{minted}{makefile}
+SOURCES = $(wildcard *.c)
+EXEC    = $(patsubst %.c, %.elf, $(SOURCES))
+DEVICE  = msp430g2553
+INSTALL_DIR=$(HOME)/ti/msp430_gcc
+
+GCC_DIR =  $(INSTALL_DIR)/bin
+SUPPORT_FILE_DIRECTORY = $(INSTALL_DIR)/include
+
+CC      = $(GCC_DIR)/msp430-elf-gcc
+GDB     = $(GCC_DIR)/msp430-elf-gdb
+
+#O0 works, O1 works, O2 doesn't -Os works
+CFLAGS = -I $(SUPPORT_FILE_DIRECTORY) -mmcu=$(DEVICE) -Os -g
+LFLAGS = -L $(SUPPORT_FILE_DIRECTORY) -T $(DEVICE).ld
+
+all: prog1 prog2 adc pwm
+
+prog1: prog1.c
+    $(CC) $(CFLAGS) $(LFLAGS) $? -o prog1.elf
+    $(CC) $(CFLAGS) $(LFLAGS) $? -S -o prog1.asm
+prog2: prog2.c
+    $(CC) $(CFLAGS) $(LFLAGS) $? -o prog2.elf
+    $(CC) $(CFLAGS) $(LFLAGS) $? -S -o prog2.asm
+adc:   adc.c
+    $(CC) $(CFLAGS) $(LFLAGS) $? -o adc.elf
+    $(CC) $(CFLAGS) $(LFLAGS) $? -S -o adc.asm
+pwm:   pwm.c
+    $(CC) $(CFLAGS) $(LFLAGS) $? -o pwm.elf
+    $(CC) $(CFLAGS) $(LFLAGS) $? -S -o pwm.asm
+
+debug: all
+    $(GDB) ${EXEC}
+
+clean:
+    rm prog1.elf prog2.elf adc.elf pwm.elf prog1.asm prog2.asm adc.asm pwm.asm
+	\end{minted}
+	
+	\section{Program 1}
+		Compiling from C, the produced Assembly file has a \textit{lot} of extra code, and appears to have been optimized differently. Below is the relevant section of the compiled .asm with some comments comparing lines to last lab's prog1.asm code.
+		
+		\begin{minted}{gas}
+.LCFI0:
+	.loc 1 21 0
+	MOV.W   #23168, &WDTCTL         ; turn off watchdog
+	.loc 1 22 0
+	MOV.B   #65, &P1DIR             ; set output direction (P1.6 and P1.0 for LEDs)
+	.loc 1 23 0
+	MOV.B   #1, &P1OUT              ; set initial state (LED1 on)
+.LBB2:
+	.loc 1 27 0
+	MOV.W   #-5536, R12             ; amount to decrement by (60000 shown as signed word)
+.L6:
+.LVL0:
+	MOV.W   R12, @R1                ; use R1 as working register to decrement (first loop)
+.L3:
+	.loc 1 28 0
+	MOV.W   @R1, R13                ; use R13 as working register for this loop
+	CMP.W   #0, R13 { JEQ    .L2    ; go to next countdown if this one has reached zero
+	.loc 1 29 0
+	ADD.W   #-1, @R1                ; decrement counter
+	BR  #.L3                        ; loop
+.L2:
+.LVL1:
+	.loc 1 27 0
+	MOV.W   R12, @R1                ; reset R1 as working register to decrement (second loop)
+.L5:
+	.loc 1 28 0
+	MOV.W   @R1, R13                ; use R13 as working register for this loop
+	CMP.W   #0, R13 { JEQ    .L4    ; break if countdown has reached zero
+	.loc 1 29 0
+	ADD.W   #-1, @R1                ; decrement counter
+	BR  #.L5                        ; loop
+.L4:
+.LVL2:
+.LBE2:
+	.loc 1 32 0 discriminator 1
+	XOR.B   #65, &P1OUT             ; switch LEDs
+	.loc 1 26 0 discriminator 1
+	BR  #.L6                        ; loop from top of loops
+		\end{minted}
+		
+		\newpage
+		This was generated using the following C code that doubles the count and thus halves the blinking rate. 
+		
+		\begin{minted}{c}
+#include <msp430.h>
+
+void main(void) {
+    volatile unsigned int count;
+    WDTCTL = WDTPW + WDTHOLD;       // Stop WDT
+    P1DIR = 0x41;                   // Set P1 output direction
+    P1OUT = 0x01;                   // Set the output
+    
+    while (1) {                     // Loop forever
+        for (volatile unsigned char i = 0; i < 2; i++) {    // decrement by 60000 twice
+            count = 60000;
+            while (count != 0) {
+                count--;            // decrement
+            }
+        }
+        P1OUT = P1OUT ^ 0x41;       // bitwise xor the output with 0x41
+    }
+}
+		\end{minted}
+	
+	\section{Program 2}
+		Below is the C code used to make the LEDs blink in the red--green--both--none pattern, using the same XOR trick described in the last lab notes.
+		
+		\begin{minted}{c}
+#include <msp430.h>
+
+volatile unsigned char stateChanger;
+
+void main(void) {
+    WDTCTL = WDTPW + WDTHOLD;   // Stop watchdog timer
+    P1DIR  = 0xF7;              // C does not have a convenient way of
+                                // representing numbers in binary; use hex instead
+    P1OUT  = 0x08;              // LEDs off
+    P1REN  = 0x08;              // enable resistor
+    P1IE   = 0x08;              // Enable input at P1.3 as an interrupt
+    stateChanger = 0x1;         // 0x01 to toggle LED0; 0x40 to toggle LED1
+
+    _BIS_SR (LPM4_bits + GIE);  // Turn on interrupts and go into the lowest
+                                // power mode (the program stops here)
+                                // Notice the strange format of the function, it is an "intrinsic"
+                                // ie. not part of C; it is specific to this chipset
+}
+
+// Port 1 interrupt service routine
+void __attribute__ ((interrupt(PORT1_VECTOR))) PORT1_ISR(void) {
+    P1OUT ^= stateChanger;      // toggle the LEDS
+    stateChanger ^= 0x40;       // 0x01 -> 0x41 -> 0x01
+    P1IFG &= ~0x08;             // Clear P1.3 IFG. If you don't, it just happens again.
+}
+		\end{minted}
+	
+	\section{Analogue to Digital Conversion}
+	
+	\section{Pulse Width Modulation}
+	
+	\section{LED Dimmer}
+\end{document}