class done

lab7interrupts/Src/keypad.s

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+# keypad.s
+# Trevor Barnes
+# CE2801-031
+# Description: Contains routines for the keypad component
+
+.syntax unified
+.cpu cortex-m4
+.thumb
+.section .text
+
+	.equ RCC_BASE, 0x40023800
+    .equ RCC_AHB1ENR, 0x30
+    .equ RCC_GPIOCEN, 1<<2
+
+    .equ GPIOC_BASE, 0x40020800 
+    .equ GPIO_MODER, 0x00
+    .equ GPIO_ODR, 0x14
+    .equ GPIO_IDR, 0x10
+    .equ GPIO_PUPDR, 0x0C
+    .equ GPIO_BSRR, 0x18
+
+    # Row 1
+	.equ k1,  0xEE
+	.equ k2,  0xED
+	.equ k3,  0xEB
+	.equ k4,  0xE7
+
+    # Row 2
+	.equ k5,  0xDE
+	.equ k6,  0xDD
+	.equ k7,  0xDB
+	.equ k8,  0xD7
+
+    # Row 3
+	.equ k9,  0xBE
+	.equ k10, 0xBD
+	.equ k11, 0xBB
+	.equ k12, 0xB7
+
+    # Row 4
+    .equ k13, 0x7E
+	.equ k14, 0x7D
+	.equ k15, 0x7B
+	.equ k16, 0x77
+
+.global KeyInit
+# Initialize the keypad GPIO port.  
+# Depending on your scanning algorithm, 
+# there may not be any work to do in this method
+KeyInit:
+
+    push {r0,r1,r2,lr}
+
+    ldr r1, =RCC_BASE
+
+    ldr r2, [r1, #RCC_AHB1ENR]
+    orr r2, r2, #RCC_GPIOCEN
+    str r2, [r1, #RCC_AHB1ENR]
+
+    # Read current PUPDR state
+    ldr r1, =GPIOC_BASE
+    ldr r2, [r1, #GPIO_PUPDR]
+
+    # Modify and write rows and columns to be "Pull-Up"
+    bfc r2, #0, #16
+    ldr r0, =0x5555
+    orr r2, r2, r0
+    str r2, [r1, #GPIO_PUPDR]
+
+    pop {r0,r1,r2,pc}
+
+.global KeyGetKeyNoblock
+# Returns in r0 a numeric code representing 
+# the button on the keypad that was pressed (1 to 16),
+# or 0 if no button is pressed
+KeyGetKeyNoblock:
+
+    push {r1,r2,lr}
+
+    bl keypadScan
+
+	mov r1, #0
+
+	ubfx r2, r0, #4, #4
+
+	cmp r2, #0xF
+	beq 1f
+
+    add r1, #1
+    cmp r0, #k1
+    beq 1f
+
+    add r1, #1
+    cmp r0, #k2
+    beq 1f
+
+    add r1, #1
+    cmp r0, #k3
+    beq 1f
+
+    add r1, #1
+    cmp r0, #k4
+    beq 1f
+
+    add r1, #1
+    cmp r0, #k5
+    beq 1f
+
+    add r1, #1
+    cmp r0, #k6
+    beq 1f
+
+    add r1, #1
+    cmp r0, #k7
+    beq 1f
+
+    add r1, #1
+    cmp r0, #k8
+    beq 1f
+
+    add r1, #1
+    cmp r0, #k9
+    beq 1f
+
+    add r1, #1
+    cmp r0, #k10
+    beq 1f
+
+    add r1, #1
+    cmp r0, #k11
+    beq 1f
+
+    add r1, #1
+    cmp r0, #k12
+    beq 1f
+
+    add r1, #1
+    cmp r0, #k13
+    beq 1f
+
+    add r1, #1
+    cmp r0, #k14
+    beq 1f
+
+    add r1, #1
+    cmp r0, #k15
+    beq 1f
+
+    add r1, #1
+    cmp r0, #k16
+    beq 1f
+
+1:
+    mov r0, r1
+
+    pop {r1,r2,pc}
+
+
+.global KeyGetKey
+# Same as KeyGetkeyNoblock, but blocks – that is, 
+# waits until a key is pressed and then returns the key code.  
+# Per discussion in lecture, you may wish to return after said key
+# is released
+KeyGetKey:
+
+    push {r1,r2,r3,lr}
+    mov r0, #0
+1:
+	mov r1, #10
+	bl usDelay
+    bl KeyGetKeyNoblock
+
+    cmp r0, #0
+    beq 1b
+2:
+# Row = Input | Col = Output
+    ldr r1, =GPIOC_BASE
+    ldr r2, [r1, #GPIO_MODER]
+    mov r3, #0x0055
+    bfi r2, r3, #0, #16
+    str r2, [r1, #GPIO_MODER]
+# "0000" -> ODR (Col)
+    ldrb r2, [r1, #GPIO_ODR]
+    mov r3, #0x0
+    bfi r2, r3, #0, #4
+    strb r2, [r1, #GPIO_ODR]
+# Store input data in r3
+    ldrb r3, [r1, #GPIO_IDR]
+    cmp r3, #0xF0
+    bne 2b
+
+    pop {r1,r2,r3,pc}
+
+
+.global KeyGetChar
+# Similar to KeyGetkey, but returns the ASCII code corresponding
+# to the key press. 
+# This method blocks. You should use a data structure in .rodata
+# to map keys to characters
+KeyGetChar:
+
+    push {r1,r2,lr}
+
+	bl KeyGetKey
+	sub r0, #1
+	mov r2, r0
+	ldr r1, =keyChars
+	ldrb r0, [r1, r2]
+
+    pop {r1,r2,pc}
+
+# Waits for input on keypad and returns that value in r0
+keypadScan:
+
+    push {r1,r2,r3,lr}
+2:
+# Row = Input | Col = Output
+    ldr r1, =GPIOC_BASE
+    ldr r2, [r1, #GPIO_MODER]
+    mov r0, #0x0055
+    bfi r2, r0, #0, #16
+    str r2, [r1, #GPIO_MODER]
+# "0000" -> ODR (Col)
+    ldrb r2, [r1, #GPIO_ODR]
+    mov r3, #0x0
+    bfi r2, r3, #0, #4
+    strb r2, [r1, #GPIO_ODR]
+# Store input data in r3
+	mov r0, r1
+    mov r1, #5
+    bl usDelay
+    mov r1, r0
+    ldrb r3, [r1, #GPIO_IDR]
+
+# Row = Output | Col = Input
+    ldr r1, =GPIOC_BASE
+    ldr r2, [r1, #GPIO_MODER]
+    mov r0, #0x5500
+    bfi r2, r0, #0, #16
+    str r2, [r1, #GPIO_MODER]
+# "0000" -> ODR (Row)
+    ldrb r2, [r1, #GPIO_ODR]
+    mov r0, #0x0
+    bfi r2, r0, #0, #4
+    strb r2, [r1, #GPIO_ODR]
+    mov r0, r1
+    mov r1, #5
+    bl usDelay
+    mov r1, r0
+# Read IDR (Row & Col)
+    ldrb r0, [r1, #GPIO_IDR]
+    orr r0, r0, r3
+
+    pop {r1,r2,r3,pc}
+
+
+.section .rodata 
+keyChars: 
+    .asciz "123A456B789C*0#D"