finished lab 3

lab4lcd/src/delay.s

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+# delay.s
+# Trevor Barnes
+# CE2801-031
+# Description: A file for handling delay routines
+
+.syntax unified
+.cpu cortex-m4
+.thumb
+.section .text
+
+.global delay_ms
+# A subroutine to create a delay of a certain number of milliseconds
+# Input: 
+#       r0: Length of delay (ms)
+delay_ms:
+
+    push {r1,r2,r3,lr}
+    mov r3,r0
+ms_delay:
+	# 250 iterations = 1/16 of a millisecond
+    mov r2, #0x10
+# Loop 16 times
+1:
+	# 250
+	mov r1, #0xFA
+# Loop 250 times
+2:
+    sub r1, #1
+    cmp r1, #0
+    bne 2b
+
+    sub r2, #1
+    cmp r2, #0
+    bne 1b
+
+	sub r0, #1
+	cmp r0, #0
+    bne ms_delay
+
+    mov r0,r3
+    pop {r1,r2,r3,pc}
+
+.global lcd_delay
+# about r1 mircoseonds
+lcd_delay:
+	# stack
+	push {lr}
+
+	lsl r1, r1, #3
+
+1:
+	sub r1, r1, #1
+    cmp r1, #0
+	bne 1b
+
+	# return
+	pop {pc}
+
+

lab4lcd/src/lcd.s

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+# lcd.s
+# Trevor Barnes
+# CE2801-031
+# Description: 
+
+.syntax unified
+.cpu cortex-m4
+.thumb
+.section .text
+
+#Fill in addresses
+	.equ RCC_BASE, 0x40023800
+    .equ RCC_AHB1ENR, 0x30
+    .equ RCC_GPIOAEN, 1<<0
+    .equ RCC_GPIOCEN, 1<<2
+
+    .equ GPIOA_BASE, 0x40020000
+    .equ GPIOC_BASE, 0x40020800 
+    .equ GPIO_MODER, 0x00
+    .equ GPIO_ODR, 0x14
+    .equ GPIO_IDR, 0x10
+    .equ GPIO_BSRR, 0x18
+
+#What pin is each of these?
+	.equ RS, 8 // PC8
+	.equ RW, 9 // PC9
+	.equ E, 10 // PC10
+
+#Commands for BSRR
+	.equ RS_SET, 1<<RS
+	.equ RS_CLR, 1<<(RS+16)
+	.equ RW_SET, 1<<RW
+	.equ RW_CLR, 1<<(RW+16)
+	.equ E_SET, 1<<E
+	.equ E_CLR, 1<<(E+16)
+
+#Globally exposed functions
+.global lcdInit
+
+#Local helper function
+PortSetup:
+    push {r1,r2,r3}
+    #Turn on Ports in RCC
+    ldr r1, =RCC_BASE
+
+    ldr r2, [r1, #RCC_AHB1ENR]
+    orr r2, r2, #RCC_GPIOAEN
+    str r2, [r1, #RCC_AHB1ENR]
+
+    ldr r2, [r1, #RCC_AHB1ENR]
+    orr r2, r2, #RCC_GPIOCEN
+    str r2, [r1, #RCC_AHB1ENR]
+
+    #Set DB Pins to Outputs
+    ldr r1, =GPIOA_BASE
+    ldr r2, [r1, #GPIO_MODER]
+
+    movw r3, 0x5500
+    movt r3, 0x0055
+    
+    orr r2,r2, r3
+
+    movw r3, 0xAA00
+    movt r3, 0x00AA
+    bic r2, r2, r3
+
+    str r2, [r1, #GPIO_MODER]
+
+    #Set RS RW E Pins to Outputs
+    ldr r1, =GPIOC_BASE
+    ldr r2, [r1, #GPIO_MODER]
+
+    movw r3, 0x0000
+    movt r3, 0x0015
+    
+    orr r2,r2, r3
+
+    movw r3, 0x0000
+    movt r3, 0x00EA
+    bic r2, r2, r3
+    str r2, [r1, #GPIO_MODER]
+
+	pop {r1,r2,r3}
+    bx lr
+
+
+#Writes instruction
+#RS=0 RW=0  R1-Arg
+#No returns
+WriteInstruction:
+	push {r2,r3,lr}
+
+	#Set RS=0,RW=0,E=0
+
+    ldr r2, =GPIOC_BASE
+
+    mov r3, RS_CLR
+    str r3, [r2, #GPIO_BSRR]
+    mov r3, RW_CLR
+    str r3, [r2, #GPIO_BSRR]
+    mov r3, E_CLR
+    str r3, [r2, #GPIO_BSRR]
+
+	#Set E=1
+    mov r3, E_SET
+    str r3, [r2, #GPIO_BSRR]
+
+	#Set R1 -> DataBus 
+    lsl r1, #4
+    ldr r3, =GPIOA_BASE
+    ldr r2, [r3, #GPIO_ODR]
+    bfc r2, #4, #8
+    orr r2, r2, r1
+    str r2, [r3, #GPIO_ODR ] 
+	#Set E=0
+    ldr r2, =GPIOC_BASE
+    mov r3, E_CLR
+    str r3, [r2, #GPIO_BSRR]
+
+	#Wait for appropriate delay
+    mov r1, #37
+    bl lcd_delay
+	pop {r2,r3,pc}
+
+
+#Writes data
+#RS=0 RW=0  R1-Arg
+#No returns
+WriteData:
+	push {r1,r2,r3,r4,lr}
+
+	#Set RS=1,RW=0,E=0
+    ldr r2, =GPIOC_BASE
+
+    mov r3, #RS_SET
+    str r3, [r2, #GPIO_BSRR]
+    mov r3, #RW_CLR
+    str r3, [r2, #GPIO_BSRR]
+    mov r3, #E_CLR
+    str r3, [r2, #GPIO_BSRR]
+	#Set E=1
+    mov r3, #E_SET
+    str r3, [r2, #GPIO_BSRR]
+	#Set R1 -> DataBus 
+	lsl r1, #4
+    ldr r3, =GPIOA_BASE
+    ldr r2, [r3, #GPIO_ODR]
+    bfc r2, #4, #8
+    orr r2, r2, r1
+    str r2, [r3, #GPIO_ODR ] 
+	#Set E=0
+    ldr r2, =GPIOC_BASE
+    mov r3, #E_CLR
+    str r3, [r2, #GPIO_BSRR]
+	#Wait for appropriate delay
+    mov r1, #37
+    bl lcd_delay
+	pop {r1,r2,r3,r4,pc}
+
+#Code to intialize the lcd
+lcdInit:
+	push {r0,r1,lr}
+
+    #Set up Ports
+    bl PortSetup
+    #Wait 40ms
+    mov r0, #40
+    bl delay_ms
+    #Write Function Set (0x38)
+    mov r1, 0x38
+    bl WriteInstruction
+    mov r1, #37
+    bl lcd_delay
+    #Write Function Set (0x38)
+    mov r1, 0x38
+    bl WriteInstruction
+    mov r1, #37
+    bl lcd_delay
+    #Write Display On/Off(0x0F)
+    mov r1, 0x0F
+    bl WriteInstruction
+    mov r1, #37
+    bl lcd_delay
+    #Write Display Clear (0x01)
+    mov r1, 0x01
+    bl WriteInstruction
+    mov r1, #2
+    bl delay_ms
+    
+    #Write Entry Mode Set (0x06)
+    mov r1, 0x06
+    bl WriteInstruction
+
+    mov r1, #37
+    bl lcd_delay
+	pop {r0,r1,pc}
+
+.global lcdClear
+    # clears the display
+    # no arguments or return
+    # includes necessary delay
+lcdClear:
+    push {r0,lr}
+    mov r1, 0x01
+    bl WriteInstruction
+    # Delay for at least 1.52ms
+    mov r0, #2
+    bl delay_ms
+    pop {r0,pc}
+
+
+.global lcdHome
+    # moves cursor to the home position
+    # no arguments or return
+    # includes necessary delay
+lcdHome:
+    push {r1,lr}
+    mov r1, #0x02
+    bl WriteInstruction
+    mov r0, #2
+    bl delay_ms
+    pop {r1,pc}
+
+.global lcdSetPosition
+    # moves cursor to the position indicated
+    # r0 is the zero-based row and r1 is the zero-based column, no return value
+    # includes necessary delay
+lcdSetPosition:
+    push {r0,r1,lr}
+    # Sub values to "actual" positions
+    sub r0, r0, #1
+    sub r1, r1, #1
+    # Shift row to actual
+    lsl r0, r0, #6
+    orr r0, r0, r1
+
+    mov r1, #0x80
+    orr r1, r1, r0
+    bl WriteInstruction
+    pop {r0,r1,pc}
+
+.global lcdPrintString
+    # prints a null terminated string to the display
+    # r0 contains the address of the null terminated string (usually located in .data or .rodata), returns the number of characters written to display in r0
+    # includes necessary delay
+lcdPrintString:
+    push {r0,r1,r2,r3,lr}
+
+    mov r2, #0
+loop:
+    ldrb r1, [r0, r2]
+    cmp r1, #0x00
+    beq done
+    bl WriteData
+    add r2, r2, #1
+    b loop
+done:
+    mov r0, r1
+    pop {r0,r1,r2,r3,pc}
+
+.global lcdPrintNum
+    # prints a (decimal) number to the display
+    # the number to be printed is in r0, values of 0 to 9999 will print, anything above 9999 should print Err.
+    # includes necessary delay
+lcdPrintNum:
+    push {r0,r1,r2,r3,r4,lr}
+
+    bl num_to_ASCII
+    # Store num in memory
+    ldr r2, =numToPrint
+    str r0, [r2]
+    # Move cursor to right-most position
+    mov r1, #16
+writeByte:
+    mov r0, #1
+    bl lcdSetPosition
+    
+    mov r4, r0
+    mov r0, #1
+    bl delay_ms
+    mov r0, r4
+
+    mov r0, r1
+    ldrb r1, [r2, r3]
+    bl WriteData
+
+    mov r4, r0
+    mov r0, #1
+    bl delay_ms
+    mov r0, r4
+
+    add r3, r3, #1
+    cmp r3, #4
+    sub r1, r0, #1
+    cmp r3, #4
+    bne writeByte
+    pop {r0,r1,r2,r3,r4,pc}
+
+# Takes in a value from 0-9999 and converts it to ASCII
+# Input:
+#       r0: Input binary value
+
+num_to_ASCII:
+
+    # If outside of range, return ASCII "Err."
+    push {r1,r2,r3,lr}
+
+    cmp r0,#0
+    blt out_of_range
+    # cmp r0,#9999
+    # bgt out_of_range
+
+# Normal conversion behavior
+    mov r1, #16
+    lsl r0, #3
+    sub r1, #3
+shift_cycle:
+
+    lsl r0, #1
+    sub r1, #1
+    cmp r1, #0
+    # Branch to encode section if shifted 16 times
+    beq encode
+
+# Verify Each Nibble is less than or equal to 4
+    ubfx r2, r0, #16, #4
+    # If value is less than or equal to 4, then skip to next nibble
+    cmp r2, #4
+    ble 2f
+    add r2, #3
+    bfi r0, r2, #16, #4
+2:  ubfx r2, r0, #20, #4
+    # If value is less than or equal to 4, then skip to next nibble
+    cmp r2, #4
+    ble 3f
+    add r2, #3
+    bfi r0, r2, #20, #4
+3:  ubfx r2, r0, #24, #4
+    # If value is less than or equal to 4, then skip to next nibble
+    cmp r2, #4
+    ble 4f
+    add r2, #3
+    bfi r0, r2, #24, #4
+4:  ubfx r2, r0, #28, #4
+    # If value is less than or equal to 4 skip to end
+    cmp r2, #4
+    ble end_verify_nibbles
+    add r2, #3
+    bfi r0, r2, #28, #4
+end_verify_nibbles:
+
+    
+    b shift_cycle
+encode:
+    mov r3, #3
+# Encode BCD numbers to ASCII
+    # Extract ones nibble
+    ubfx r2, r0, #16, #4
+    # Insert ones nibble
+    bfi r1, r2, #0, #4
+    # Insert 3 in front of nibble for ASCII encoding
+    bfi r1, r3, #4, #4
+
+    # Extract tens nibble
+    ubfx r2, r0, #20, #4
+    # Insert tens nibble
+    bfi r1, r2, #8, #4
+    # Insert 3 in front of nibble for ASCII encoding
+    bfi r1, r3, #12, #4
+
+    # Extract hundreds nibble
+    ubfx r2, r0, #24, #4
+    # Insert hundreds nibble
+    bfi r1, r2, #16, #4
+    # Insert 3 in front of nibble for ASCII encoding
+    bfi r1, r3, #20, #4
+
+    # Extract thousands nibble
+    ubfx r2, r0, #28, #4
+    # Insert thousands nibble
+    bfi r1, r2, #24, #4
+    # Insert 3 in front of nibble for ASCII encoding
+    bfi r1, r3, #28, #4
+
+    b end_ASCII
+out_of_range:
+    # Insert ASCII "Err."
+    movw r1, #0x722E
+    movt r1, #0x4572
+
+end_ASCII:
+    # Return value in r0
+	mov r0, r1
+    pop {r1,r2,r3,pc}
+
+
+.global lcdBusyWait
+# Loops until the busy flag is 0
+lcdBusyWait:
+
+    push {r0,r1,r2,r3,lr}
+
+    ldr r1, =GPIOA_BASE
+    ldr r2, [r1, #GPIO_MODER]
+
+    mov r3, #0
+    
+    orr r2, r2, r3
+
+    movw r3, 0xFF00
+    movt r3, 0x00FF
+    bic r2, r2, r3
+
+    str r2, [r1, #GPIO_MODER]
+
+    #Set RS=0, RW=1, E=1
+    ldr r2, =GPIOC_BASE
+
+    mov r3, #RS_CLR
+    str r3, [r2, #GPIO_BSRR]
+    mov r3, #RW_SET
+    str r3, [r2, #GPIO_BSRR]
+    mov r3, #E_SET
+    str r3, [r2, #GPIO_BSRR]
+busy:
+	#Set E=
+    mov r3, #E_SET
+    str r3, [r2, #GPIO_BSRR]
+	#Set Databus -> R1
+    ldr r3, =GPIOA_BASE
+    ldr r1, [r3, #GPIO_IDR]
+	#Set E=0
+    ldr r2, =GPIOC_BASE
+    mov r3, #E_CLR
+    str r3, [r2, #GPIO_BSRR]
+
+    mov r2, #0x0010
+    and r1, r2
+    lsr r1, #4
+    # Are we still busy?
+    cmp r1, #1
+    beq busy
+
+# Return DB port to original mode 
+    ldr r1, =GPIOA_BASE
+    ldr r2, [r1, #GPIO_MODER]
+
+    movw r3, 0x5500
+    movt r3, 0x0055
+    
+    orr r2,r2, r3
+
+    movw r3, 0xAA00
+    movt r3, 0x00AA
+    bic r2, r2, r3
+
+    str r2, [r1, #GPIO_MODER]
+
+    pop {r0,r1,r2,r3,pc}
+
+
+.section .data
+numToPrint:
+    .word 0

lab4lcd/src/main.s

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+# main.s
+# Trevor Barnes
+# CE2801-031
+# Lab 3: LCD API
+# Description: The driver for Lab 4. Displays the ASCII
+#              values from the previous lab.
+
+.syntax unified
+.cpu cortex-m4
+.thumb
+.section .text
+
+.global main
+
+
+main:
+    bl lcdInit
+
+    mov r0, #10
+    bl countDown
+
+    bl lcdClear
+
+    ldr r0, =msg
+    bl lcdPrintString
+    
+end:
+    b end
+
+# r0 - value to be counted down from (0-9999)
+countDown:
+    push {r0,r1,lr}
+loop:
+    # Print number
+    bl lcdPrintNum
+    mov r1, r0
+    mov r0, #1
+    # Save current value before delay subroutine
+    bl lcdHome
+    mov r0, #1000
+    bl delay_ms
+    mov r0, r1
+    cmp r0, #0
+    beq done
+    sub r0, r0, #1
+
+    b loop
+done:
+    pop {r0,r1,pc}
+
+
+
+
+.section .rodata
+msg:
+    .asciz "Hello World!"
+