Generate random numbers using 8-bit data from AVR microcontroller

Source program: SLAVR737.ASM
uses AVR microcontroller 8-bit data to generate random numbers, outputs random numbers from PORTA and PORTC, and displays them on 8X8 LEDs. For hardware wiring circuit, see "7.3.8 Button Guessing". The seed of the random number is set by the program (or an external switch). After the seed is started, the shift register returns to the cycle with a mutually exclusive XOR logic combination.

.include"8515def.inc"
    rjmp RESET    
.def temp =r16 ; register.def
temp1 =r17 ; register 1
.def udata =r21 ; store random number and send to port A.def
ddata =r22 ; store random number and send to port C.cseg
.org
0x10
RESET: ldi temp,high(RAMEND); set stack pointer
    out SPH,temp             
    ldi temp,low(RAMEND)     
    out SPL,temp
      
        ldi temp,0xff ; set port A and port C as output
        out ddra,temp ; send direction register A
        out ddrc,temp ; send direction register C
start: wdr ; turn off watchdog
        ldi udata,0x6a ; set initial value of random number
        ldi ddata,0x3c ; 
startp: out porta,udata ; output to port A
        out portc,ddata ; output to port C
        ldi temp,0x80 ;Set delay constant
        rcall delay ;Call delay subroutine
        rcall randm ;Call 16-bit random number subroutine
        rjmp startp  
delay: ; General delay subroutine omitted
....
Principle diagram of 16-bit random number generation
8-bit shift register generates random number cyclic combination
bit number cyclic input combination S=2＾n-1 Qn XOR Qm
   8 Q2 ⊕ Q3 ⊕ Q4 ⊕ Q8 (The current program button guesses the number using 8 digits)
   9 Q5 ⊕ Q9
  10 Q7 ⊕ Q10
  11 Q9 ⊕ Q11
  12 Q2 ⊕ Q10 ⊕ Q11 ⊕ Q12
  13 Q1 ⊕ Q11 ⊕ Q12 ⊕ Q13
  14 Q2 ⊕ Q12 ⊕ Q13 ⊕ Q14
  15 Q14 ⊕ Q15
  16 Q4 ⊕ Q13 ⊕ Q15 ⊕ Q16

randm: ;Generate 16-bit random number subroutine
   mov temp,udata ;Generate random number for port A
          mov temp1,udata ; 
          rol temp ;Left circular shift through the carry bit
          eor temp1,temp ;XOR
          rol temp ; Left circular shift through the carry bit
          rol temp ; Left circular shift through the carry bit
          eor temp1,temp ;XOR
          mov temp,ddata ; Generate random number for port C
          swap temp ; Left circular shift through the carry bit
          eor temp,temp1 ;XOR Left circular shift through the carry bit
          rol temp ; Left circular shift through the carry bit
          rol ddata ; Left circular shift through the carry bit
          rol udata ; Left circular shift through the carry bit
          ret ;Subroutine returns to
7.3.8 Button guessing program
source code: SLAVR738.ASM
In many occasions, such as button guessing (computer lottery, computer selecting lucky numbers), the game start button waits for an irregular and unordered data to be generated, that is, a random number generator is required. The seed of the random number is set by the program (it can also be set by an external switch). After the seed is started, the shift register returns to the cycle with a mutually exclusive XOR logic combination. The schematic diagram for generating random numbers is as follows:
Principle diagram of 16-bit random number generation
8-bit shift register generates random number cyclic combination
bit number Circular input combination S=2＾n-1 Qn XOR Qm
   8 Q2 ⊕ Q3 ⊕ Q4 ⊕ Q8 (The current program button guesses the number using 8 digits)
   9 Q5 ⊕ Q9
  10 Q7 ⊕ Q10
  11 Q9 ⊕ Q11
  12 Q2 ⊕ Q10 ⊕ Q11 ⊕ Q12
  13 Q1 ⊕ Q11 ⊕ Q12 ⊕ Q13
  14 Q2 ⊕ Q12 ⊕ Q13 ⊕ Q14
  15 Q14 ⊕ Q15
  16 Q4 ⊕ Q13 ⊕ Q15 ⊕ Q16


8X8 LED array, in order to prevent users from predicting the change value of the random number corresponding to the pressing time when the machine is turned on, the LED subtitles are displayed with advertising animation screens, and the random number is changed so that the starting value of the random number cannot be predicted. There are four advertising animation screens, each with 8 bits of data. See "org dpfstb";

by pressing the button (PD1), AVR generates a random number with 8 bits of data, and outputs the random number from PORTA and PORTC, and displays the fun and real button guessing on the 8X8 LED.
.include "8515def.inc"
.def peed = r16
.def     DSP n = r17 ;Store the initial animation times.def
temp2 = r18
.def temp1 = r19
.def temp = r20
.def scndp = r21 
.def cnt = r22
.def rdata = r23 ;Store the random seed number.def
rdata9 = r24
.equ dpfstb = 0x01e0 ;The first address of the size rectangle chart.equ
randtb = 0x0210 ;The first address of the random number seed table.equ
numbertb = 0x0240 ;The first address of the 0-9 digital table.org
$0000
    rjmp RESET ;Reset Handle
.cseg
.org $0010
RESET: ldi peed, high (RAMEND) ;Set the stack $25F, see the device configuration file "8515def.inc"
        out SPH,peed
        ldi peed,low(RAMEND)
        out SPL,peed
        ldi peed,0xff ;initialize the port, 
        out ddra,peed ;set port A as output
        out ddrc,peed ;set port C as output
        ldi peed,0xfd ;PD1 as input, and connect internal pull-up resistor
        out ddrd,peed ;PD1 as input, the rest as output
        ldi peed,0xff ;turn off port D
        out portd,peed
        ldi peed,0x13 ;display screen times
start: ldi dspn,0x06 ;display initial animation
        ldi zh,high(dpfstb*2)  
        ldi zl,low(dpfstb*2)  
dsp FM : rcall ldtb8 ;call program area number and send it to RAM
        ldi temp2,0xa0 ;display animation screen times
dspfm1: rcall s CAN 1 ;Call to get data from memory and display it once
        sbis     PIN d,01 ;The bit of I/O port is set to jump, detect PD1 is pressed or not
        rjmp getseed ; Detect PD1 is pressed and go to
        dec temp2 ;-1
        brne dspfm1 ;If not 0, go to
        dec dspn ; Number of initial screens -1
        brne dspfm ; If not 0, go to
        rjmp start ;Go to display initial animation
getseed:inc temp ;+`1, select random number seed according to the time PD1 is pressed
        sbis pind,01 ;The bit of I/O port is set to jump, detect PD1 is pressed or not
        rjmp getseed ; Detect PD1 is pressed and continue counting
        andi temp,0x1f ;The button is released, get the random number seed and add 0X0F
        ldi zh,high(randtb*2)
        ldi zl,low(randtb*2)
        add zl,temp
        lpm
        mov rdata,r0 ;Get the random number seed
next: ldi dspn,0x08 ;Display 8 different random numbers;
repeet: rcall randm ;Call the random number generation
        subrcall dspnumber ;Call and display 8 different random numbers
        dec dspn ;-1
        brne repeet ;dspn is not 0
        rcall randm ; call the random number generating subroutine
guess1: rcall dspnumber ; call and display the same random number until a key is pressed
        sb IC     pind,01 ; release and then execute (I/O port clears and jumps)
        rjmp guess1 ; switch to display the same random number until a key is pressed
wait: rcall dspnumber ;
        sbis pind,01
        rjmp wait ; wait for the button to be pressed
        ldi rdata9,0x03 ; display the animation three times
start0: ldi dspn,0x06 ; display six pictures each time
        ldi zh,high(dpfstb*2)  
        ldi zl,low(dpfstb*2)  
dspfm0: rcall ldtb8 ; call to get data from the program area pointed to by Z and send it to the memory 0080-0087
        ldi temp2,0xa0 ; display times
dspfm1a:rcall scan1 ;Call to fetch data from memory 0080-0087 and display it once
        dec temp2 ;-1
        brne dspfm1a ;If not 0, go to
        dec dspn ;Show the initial animation times -1
        brne dspfm0 ;If not 0, go to
        dec rdata9 ;Show animation three times -1
        brne start0 ;If not 0, go to
        rjmp next ;Go to display 8 different random numbers
dspnumber: ;Display a subroutine with a number from 0 to 9
        ldi zh,high(numbertb*2)
        ldi zl,low(numbertb*2)
        add zl,rdata9
        rcall ldtb8 ;Get data
        ldi temp2,0xa0 ;The number is repeatedly displayed A0H times
dspn1: rcall scan1
        dec temp2
        brne dspn1
        ret
scan1: push xl ;Fetch data from memory 0080-0087 and display it once
        ldi temp,0b01111111
        mov scndp,temp
        ldi cnt,0x08
col1: out portc,scndp ;display a column of the screen
        ld r1,x+
        out porta,r1
        rcall delay
        sec
        ror scndp
        dec cnt
        brne col1
        pop xl
        ret
ldtb8: ldi xl,0x80 ;get data from the program area pointed to by Z and send them to memory 0080-0087
        ldi xh,0x00
        ldi temp1,0x08
        push xl  
nexld1: lpm
        st x+,r0
        ld r0,z+
        dec temp1
        brne nexld1
        pop xl
        ret
delay: ;general delay subroutine is omitted
....
randm: mov temp,rdata ;generate 8N (0≤N≤9) random number subroutine
        mov temp1,rdata
        swap temp1
        eor temp,temp1
        rol temp1
        eor temp,temp1
        rol temp1
        eor temp,temp1
        rol temp
        rol rdata
        mov rdata9,rdata
        andi rdata9,0x0f
        cpi rdata9,0x0a
        brsh randm ;Generate a random number 0≤RDATA9≤9
        lsl rdata9
        lsl rdata9
        lsl rdata9
        ret

.cseg
.org dpfstb; ;Size and size box font table
; small o
.db 0b00000000,0b00000000,0b00000000,0b00011000
.db 0b00011000,0b00000000,0b00000000,0b00000000
.db 0b00000000,0b00000000,0b00111100,0b00100100
.db 0b00100100,0b00111100,0b00000000,0b00000000
.db 0b00000000,0b01111110,0b01000010,0b01000010
.db 0b01000010,0b01000010,0b01
111110,0b00000000 ;big o
.db 0b11111111,0b10000001,0b10000001,0b10000001
.db 0b10000001,0b10000001,0b10000001,0b11111111
.db 0b00000000,0b01111110,0b01000010,0b01000010
.db 0b01000010,0b01000010,0b01111110,0b00000000
.db 0b00000000,0b00000000,0b00111100,0b00100100
.db 0b00100100,0b00111100,0b00000000,0b00000000
.cseg
.org randtb ;随机数种子表
.db 0x5a,0x7b,0x5b,0x4f,0x66,0x6d,0x7d,0x07
.db 0x3b,0x8c,0x67,0x9a,0x99,0x7e,0x2d,0x3e
.db 0x5c,0x6d,0x5b,0x7e,0xf6,0xe7,0x4c,0xc8
.db 0x69,0x9c,0xe2,0x75,0x6c,0xd3,0xe8,0x9a
.cseg
.org numbertb ;0-9数字字形表
;0
.db 0b00111000,0b01000100,0b01000100,0b01000100
.db 0b01000100,0b01000100,0b01000100,0b00111000
;1
.db 0b00010000,0b00011000,0b00010000,0b00010000
.db 0b00010000,0b00010000,0b00010000,0b00111000
;2
.db 0b00011100,0b00100 010,0b00100000,0b00010000
.db 0b00001000,0b00000100,0b00000010,0b00111110
;3
.db 0b00111100,0b00010000,0b00001000,0b00010000
.db 0b00100000,0b00100000,0b00100010,0b00011100
;4
.db 0b00100000,0b00110000,0b00101000,0b00100100 .db 0b00100010,0b1111111 0,0b00100000,0b00100000 ;5 .db 0b01111110,0b00000010,0b00111110,0b01000000 .db
0b01000000,0b01000000,0b01000010,0b00111100 ;6 .db 0b00110000,0b00001000,0b00000100,0b00111100 .db 0b01000100,0b01000100,0b01000100,0b00111000 ;7 .db 0b01111100,0b0100000 0,0b00100000,0b00010000 .db 0b00001000,0b00001000,0b00001000,0b00001000 ;8 .db 0b00111000,0b01000100,0b01000100,0b00111000 .d b 0b01000100,0b01000100,0b01000100,0b00111000 ;9 .db 0b00111000,0b01000100,0b01000100,0b01111000














.db 0b01000000,0b01000000,0b01000100,0b00111000