AVR Assembly Code Fundamentals

AVR Assembly Code Questions

• LDI R21, 0x10; LDI R22, 0x05; ADD R21, R22 results in R21 = 0x15 due to adding the values in R22 to R21
• The OUT instruction sends data from a register to an I/O register
• LDI R21, 0x10; SUB R21, 0x04 results in R21 having a value of 0x06, which is the result of the subtraction
• LDI R21, 0x0A' loads the constant value 0x0A into register R21 using the LDI instruction
• LDI R21, 0x10; DEC R21 will result in R21 = 0x0F due to decrementing R21
• MOV R22, R21 copies the value from R21 to R22 using the MOV instruction
• LDI R21, 0x05; INC R21 results in R21 = 0x06 due to incrementing R21
• LDI R21, 0x01; ADD R21, R21 results in R21 = 0x02 as R21 is added to itself
• RJMP does a jump to a relative address within ±2K range
• LDI R21, 0x03; SUB R21, 0x02 will result in R21 containing 0x01, which is the result of 3-2
• LDI R21, 0x05; MOV R22, R21; ADD R21, R22 results in R21 = 0x0A because R21 becomes 5 + 5
• STS 0x100, R21 uses the STS instruction to store the value of R21 in memory location 0x100
• LDI R21, 0x02; ADD R21, 0x03 adds 0x02 and 0x03, storing the result in R21
• LDI R21, 0x02; ADD R21, 0x03 results = R21 = 0x05
• LDI R21, 0x04; SUB R21, 0x02 results in R21 = 0x02 as 4 - 2 = 2
• ADD R21, R22 adds the contents of R22 to R21
• LDI R21, 0x10; ADD R21, 0x05; MOV R22, R21 results in R21 = 0x15 and R22 = 0x15
• SBI sets a specific bit in an I/O register to HIGH
• LDI R21, 0x03; DEC R21 results in R21 = 0x02 because R21 is decremented
• LDI R21, 0x10 loads an immediate value into register R21 using the LDI instruction
• BRNE branches if the result is not zero
• STS stores data from a register into SRAM
• MOV moves data between two registers
• LDI R21, 0x01; ADD R21, 0x01 results in R21 = 0x02 because R21 is incremented by one
• CMP is used to compare two registers
• The INC instruction increments a register by 1
• BRNE would be used to execute a conditional jump
• NOP does nothing (used for timing)
• OUT loads data from a register to an I/O port
• RJMP jumps to a nearby label (±2K range)
• LDI loads a constant value into a register
• ADD Adds the contents of two registers.
• MOV transfers data from one register to another
• OUT loads data from a register to an I/O register
• CMP can test if two registers are equal
• BRGE branches if the result is greater than or equal to zero
• JMP jumps to a specific address in memory
• LDI R21, 0x05; DEC R21 will result in R21 = 0x04
• AND performs a logical AND operation between two registers
• LPM loads data from the flash memory to a register
• LDI R21, 0x10; ADD R21, 0x05 results in R21 = 0x15
• CMP would be used to check if two registers are equal
• BRMI branches if the result is negative
• LDI R21, 0x07; ADD R21, 0x01 will result in R21 = 0x08
• OR is used to perform a bitwise OR operation
• LSL shifts the contents of a register left by one bit
• SBC: Subtract with carry
• CLR is used to clear a register to zero
• IN loads data from an I/O register to a CPU register
• BRNE branches if the result is not zero