; ===============================================================================

; Ping Pong - Picoblaze application for the BASYS kit

; 

; # The command below will create a BlockROM for the hardware design

               VHDL      "JTAG_Loader_ROM_form.vhd", "Display_demo_rom.vhd""Display_demo_rom"

; # The commands below will download code directly to BROM via JTAG

; # Note! Will only works with Printerport JTAG or Xilinx USB JTAG programmer

; COE       "Romfile.COE"

; EXEC      "JTAG_LOADER.BAT"

; # Please comment out the commands above when not used



; ==============================================================================

; Port Definitions  DSIO = both IN and OUT locations

Bcd0           DSIO      0                     ; Least significant digit

Bcd1           DSIO      1                     ; Least significant digit

Bcd2           DSIO      2                     ; Least significant digit

Bcd3           DSIO      3                     ; Least significant digit

Bcd_lo         DSIO      4                     ; Two least sign. digits

Bcd_hi         DSIO      5                     ; Two most sign. digits

Dp             DSIO      6                     ; Four decimal points

Timer_Scale    DSOUT     7                     ; Timer scale (1 = 0.01 sec)

Led            DSIO      9                     ; 8-Leds

DIPSW_port     DSIN      20                    ; 8-Dip Switches

Buttons        DSIN      21                    ; 4-push buttons

; ----------------------------------------------------------------------------

Scan_Code      DSIN      24                    ; From keyboard

Scan_Ready     DSIN      25                    ; Bit0 = Readyflag

; ----------------------------------------------------------------------------

VideoRAM       DSIO      32                    ; 4-bit <- Line:Pixel

Line           DSIO      33

Pixel          DSIO      34

NewLine        DSOUT     35                    ; Automatic Line+1

NewPixel       DSOUT     36                    ; Automatic Pixel+1

CrLf           DSOUT     37                    ; Automatic Line:Pixel+1



HCnt           DSIN      40

VCnt           DSIN      41



; =============================================================================

; = Register usage

; =============================================================================

R0             EQU       s0

R1             EQU       s1

R2             EQU       s2

R3             EQU       s3

R4             EQU       s4

R5             EQU       s5

R6             EQU       s6

R7             EQU       s7

R8             EQU       s8

; -----------------------------Special register use----------------------------

R_Button       EQU       s9

R_State        EQU       sA

; -----------------------------Interrupt registers-----------------------------

; This registers should only be used in ISR or rutines call from ISR

IR0            EQU       sB                    ; Reg used by Interrupt

IR1            EQU       sC                    ; Reg used by Interrupt

IR2            EQU       sD                    ; Reg used by Interrupt

; -----------------------------Not used in this program------------------------

Mode_reg       EQU       sF                    ; operating mode of processor





Start_Stop     EQU       %010000               ; <- R_Button

Lap_Reset      EQU       %100000               ; <- R_Button

; ============================================================================

; =  Scratch pad memory locations

; ============================================================================

Counter        EQU       0

Counter_HB     EQU       1



; -----------------------------------------------------------------------------

Last_Buttons   EQU       18



Half_sec       EQU       20

; -----------------------------------------------------------------------------

; Initialise the system

; 

Cold_Start:    LOAD      R0, 5

               OUT       R0, Timer_Scale

               LOAD      R0, $0B

               OUT       R0, Dp

               LOAD      R0, 5

               OUT       R0, Line

               OUT       R0, Pixel

               EINT                            ; enable interrupt

; 

; #############################################################################

; #    M a i n   must be called from every state

; #############################################################################

Main: 



; ==============================================================================

Demo_loop: 

wait0: 

               IN        R0, Scan_Ready

               TEST      R0, 1

               JUMP      NZ, Wait0

wait1: 

               IN        R0, Scan_Ready

               TEST      R0, 1

               JUMP      Z, wait1

               ADD       R1, 1

               OUT       R1, Led

               IN        R0, BCD_lo

               OUT       R0, BCD_hi

               IN        R0, Scan_Code

               OUT       R0, BCD_lo

               JUMP      Demo_loop



; == Called by interrupt =======================================================

; This rutine let Decimal Point 2 toggle every 0.5 sec

Half_Sec_Rutine: 

               IN        IR1, Dp

               XOR       IR1, $04

               OUT       IR1, Dp

               RET       

no_blink: 

               LOAD      IR1, $0F

               OUT       IR1, Dp

               RET       



; == Called by interrupt =======================================================

; This rutine will detect if any Buttons pressed since the last call

; Detections will be stored in Button_Reg together with the actual status

Scan_button_rutine: 

               IN        IR0, Buttons          ; Read New xxxx.3210 buttons

               FETCH     IR1, Last_Buttons     ; Get the Last scan

               STORE     IR0, Last_Buttons     ; Remember the xxxx.3210 for later

               XOR       IR1, $0F              ; Negate bit 3..0

               AND       IR1, IR0              ; Pressed <= not Last and New

               SL0       IR1

               SL0       IR1

               SL0       IR1

               SL0       IR1

               OR        R_Button, IR1         ; Set if any pressed

               AND       R_Button, $F0

               OR        R_Button, IR0

               RET       



; ==============================================================================

Pattern1: 

               IN        IR0, VideoRAM

               ADD       IR0, 1

               OUT       IR0, NewLine

               IN        IR0, VideoRAM

               ADD       IR0, 1

               OUT       IR0, CrLf

               RET       

; ==============================================================================

Pattern2: 

               IN        IR0, VideoRAM

               IN        IR1, DIPSW_port

               ADD       IR0, IR1

               OUT       IR0, NewLine

               IN        IR0, VideoRAM

               ADD       IR0, 1

               OUT       IR0, CrLf



               RET       

; ==============================================================================

Demo_Counter: 

               FETCH     IR0, Counter

               ADD       IR0, 1

               STORE     IR0, Counter

               OUT       IR0, Bcd_Lo

               FETCH     IR0, Counter + 1

               ADDC      IR0, 0

               STORE     IR0, Counter + 1

               OUT       IR0, Bcd_Hi

               RET       

; ==============================================================================

Analyser: 

               LOAD      IR2, 2

               IN        IR1, Scan_Ready

               TEST      IR1, %01000000

               JUMP      NZ, xxx

               LOAD      IR2, 4

xxx: 

               OUT       IR2, CrLf

               RET       

; == Called by interrupt ======= Interrupt service routine (ISR) ===============

               ORG       $3E0

ISR: 

               CALL      Pattern2



               RETI      ENABLE

; 

; Interrupt vector

; 

               ORG       $3FF

               JUMP      ISR

               END