Can you explain line for line what this easyAVR code does in comment annotations
ID: 2082351 • Letter: C
Question
Can you explain line for line what this easyAVR code does in comment annotations? for embedded systems
TABLE DB 3FH ; 0
DB 06H ;1
DB 5BH ;2
DB 4FH ;3
DB 66H ;4
DB 6DH ;5
DB 7DH ;6
DB 07H ;7
DB 7FH ;8
DB 6FH ;9
.INCLUDE "M32dDEF.INC"
LDI R16, HIGH(RAMEND) ; Initialized the stack pointer ( standard)
OUT SPH, R16
LDI R16 , LOW(RAMEND)
OUT SPL, R16
MAIN: ; Main Loop that initializes subroutines through the code
LDI r16, 0b00000000
OUT DDRB, R16
OUT DDRB, R16
IN PINB, R16
IN R17, PIND
.MACRO INTSTACK
LDI R16, HIGH (RAMEND)
OUT SPH, R16
LDI R16,LOW (RAMEND)
OUT SPL, R16
.ENDMACRO
INSTACK
ST x, R16
ST y, R17
ST R18, xl
ST R19, xh
ST R20, yl
ST R21, yh
LDI zl,low (segment <<1)
LDI zh, high (segment <<1)
LDI R22, 0x0F
OUT DDRA, R22
LDI zl, R18
LPM z, R18
OUT R18, porta1
LDI zl, R19
LPM z, R19
OUT R19, porta2
LDI zl,R20
LPM z, R20
OUT r20, porta3
LDI zl,R21
LPM z, R21
OUT R21, porta4
.ORG 0x500
.DB '0x3f', '0x06', '0x5b', '0x4f', '0x66', '0x6d', '0x7d', '0x07', '0x7f', '0x6f'
Explanation / Answer
in the table DB stands for data byte. Total 10 data bytes are initialized.
LDI R16, HIGH(RAMEND) ; % Initialized the stack pointer ( standard)
OUT SPH, R16 % value of SPH(stack pointer high) transferred to register 16 (R16)
LDI R16 , LOW(RAMEND) % % Initialized the stack pointer ( standard)
OUT SPL, R16 % value of SPL(stack pointer Low) transferred to register 16 (R16)
MAIN: ; Main Loop that initializes subroutines through the code
LDI r16, 0b00000000 % load immediate the value 0b00000000 into r16
OUT DDRB, R16 % DDRB=data direction register B , value of DDRB to R16
OUT DDRB, R16 % DDRB=data direction register B , value of DDRB to R16
IN PINB, R16 % value or R16 transfered to PINB (pin register B)
IN R17, PIND % value or PINB transfered to R17
.MACRO INTSTACK %macro starts
LDI R16, HIGH (RAMEND) % Initialized the stack pointer ( standard)
OUT SPH, R16 % value of SPH(stack pointer high) transferred to register 16 (R16)
LDI R16,LOW (RAMEND) % Initialized the stack pointer ( standard)
OUT SPL, R16 % value of SPL(stack pointer low) transferred to register 16 (R16)
.ENDMACRO % macro ends
INSTACK
ST x, R16 % store x to R16
ST y, R17 % store x to R17
ST R18, xl % store R18 to xl
ST R19, xh % store R19 to xh
ST R20, yl % store R20 to yl
ST R21, yh % store R21 to yh
LDI zl,low (segment <<1)
LDI zh, high (segment <<1)
LDI R22, 0x0F % load immediate the value 0xoF into R22
OUT DDRA, R22 % value of DDRA transferred to register 22 (R22)
LDI zl, R18 % load R18 value in zl
LPM z, R18 %load program memory - value of R18 into z
OUT R18, porta1 % send R18 value to porta1
LDI zl, R19 % load R19 value in zl
LPM z, R19 %load program memory - value of R19 into z
OUT R19, porta2 % send R19 value to porta2
LDI zl,R20 % load R120value in zl
LPM z, R20 %load program memory - value of R20 into z
OUT r20, porta3 % send R20 value to porta3
LDI zl,R21 % load R21 value in zl
LPM z, R21 %load program memory - value of R21 into z
OUT R21, porta4 % send R21value to porta4
.ORG 0x500
.DB '0x3f', '0x06', '0x5b', '0x4f', '0x66', '0x6d', '0x7d', '0x07', '0x7f', '0x6f'
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