Ordinary MCU Teaching——Lecture 12 MCU Instructions (VI)

ANL A,Rn; The values ​​in A and Rn are bitwise ANDed, and the result is sent to A

ANL A,direct; The values ​​in A and direct are bitwise ANDed, and the result is sent to A

ANL A,@Ri; A and the value in the indirect addressing unit @Ri are bitwise ANDed, and the result is sent to A

ANL A,#data; A and the immediate data are bitwise ANDed, and the result is sent to A

ANL direct,A; the value in direct and the value in A are bitwise ANDed, and the result is sent to direct

ANL direct, #data; The value in direct is bitwise ANDed with the immediate data, and the result is sent to direct.

The key to these instructions is to know what logical AND is. Here logical AND refers to bitwise AND.

(71H) 01110001

（56H） 00100110

The result is 00100000, which is 20H. From the above formula, we can see that if one of the two values ​​involved in the operation is 0, the result of that bit will be 0. If both are 1, the result will be 1.

Once you understand the logical AND operation rules, the result will come out naturally. See the comments after each instruction

MOV A,#45H ;(A)=45H

MOV R1,#25H ;(R1)=25H

MOV 25H,#79H ;(25H)=79H

ANL A,@R1; 45H and 79H are bitwise ANDed, and the result is sent to A, which is 41H (A) = 41H

ANL 25H,#15H; The value in 25H (79H) and 15H result in (25H) = 11H)

ANL 25H,A; The value in 25H (11H) and the value in A (41H) are ANDed, and the result is (25H) = 11H

After knowing the function of logical and instruction, the function of logical or and logical exclusive or is very simple. Logical or is bitwise "or", that is, all "1" is 1, all "0" is 0. Example:

10011000

or 01100001

Result 11111001

XOR is a bit-wise XOR, where the same is "0" and different is "1". Example:

10011000

XOR 01100001

Result 11111001

Or the command:

ORL A,Rn; The values ​​in A and Rn are bitwise ORed, and the result is sent to A

ORL A,direct; A and the value in the indirect addressing unit @Ri are bitwise ORed, and the result is sent to A

ORL A,#data; A and the value in direct are bitwise ORed, and the result is sent to A

ORL A,@Ri; A and data are bitwise ORed, and the result is sent to A

ORL direct,A; the value in direct and the value in A are bitwise ORed, and the result is sent to direct

ORL direct,#data; The value in direct and the immediate data are bitwise ORed together, and the result is sent to direct.

XOR instruction:

XRL A,Rn; The values ​​in A and Rn are bitwise XORed, and the result is sent to A

XRL A,direct; The values ​​in A and direct are bitwise XORed, and the result is sent to A.

XRL A,@Ri; A and the value in the indirect addressing unit @Ri are bitwise XORed, and the result is sent to A

XRL A,#data; A and immediate data are bitwise XORed, and the result is sent to A

XRL direct,A ; The value in direct and the value in A are bitwise XORed, and the result is sent to direct

XRL direct,#data; The value in direct and the immediate data are bitwise XORed, and the result is sent to direct.

MOV A,#24H

MOV R0,#37H

ORL A,R0

XRL A,#29H

MOV 35H,#10H

ORL 35H,#29H

MOV R0,#35H

ANL A,@R0

Unconditional transfer instructions

Short transfer instructions

AJMP addr11

Long transfer instructions

LJMP addr16

Relative jump instructions

SJMP rel

JMP @A+DPTR

This instruction is also used to jump. Where does it jump to? This cannot be simply determined by the label. Let's start with a practical example.

MOV DPTR,#TAB ; send the address represented by TAB to DPTR

MOV A,R0; Get data from R0 (see the following description for details)

MOV B,#2

MUL A,B; multiply the value in A by 2 (see the following description for details)

JMP A,@A+DPTR ; Jump

TAB: AJMP S1 ; Jump to table

AJMP S2

AJMP S3

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　　See Figure 2. The previous program reads in the key values. For example, after pressing the ''''A''' key, the key value is 0, and after pressing the ''''B'''' key, the value is ''''1'''', and so on. Then it jumps according to different values. For example, if the key value is 0, it jumps to S1 for execution, and if it is 1, it jumps to S2 for execution. . . . How to implement this function?

　　Let's start from the bottom of the program. There are several AJMP statements. These AJMP statements are finally stored in the memory like this (see Figure 3). That is, each AJMP statement occupies two memory spaces and is stored continuously. The address stored in AJMP S1 is TAB. We don't need to know what TAB is. We can leave it to the assembler to calculate.

Please analyze the situation after pressing the keys "A", "C", "D", etc.

　　In this way, we use JMP @A+DPTR to realize the requirement of jumping to the corresponding program segment to execute when pressing a key. Let me ask you another question, why do we need to multiply the key value by 2? If all the instructions below the routine are replaced with LJMP, that is:

LJMP S1, LJMP S2... Can this program still be executed correctly? If not, how should it be modified?