;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; ; ; pong version 1.0 ; ; by brad slattery 2008 ; ; ; ; a pong game for the 8x8 game board ; ; ; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; LIST p=16f648a ; tell assembler what chip we are using include "P16f648a.inc" ; include the defaults for the chip __config 0x3f18 ; sets the configuration settings (oscillator type etc.) PC equ 0x02 ; The program counter is now refered to as PC cblock 0x20 ; start of general purpose registers counta ; used in the delay routine countb ; used in the delay routine x_coordinate ; used to hold the dots x_coordinate y_coordinate ; used to hold the dots y_coordinate player_1_paddle ; holds the players paddle data ball_x ; holds the balls x co-ordinate ball_y ; holds the balls y co-ordinate ball_up ; holds the ball up data ball_down ; holds the ball down data ball_left ; holds the ball left data ball_right ; holds the ball right data ball_refresh ; holds the ball refresh data button_timer ; used to help in slowing down the button repeat rate (it prevents the car from moving many times for one button press) button_adjust ; used to help in slowing down the button repeat rate (it prevents the car from moving many times for one button press) stop_repeat ; used to help in slowing down the button repeat rate (it prevents the car from moving many times for one button press) endc org 0x0000 ; org sets the start address of our program to 0000 hex movlw h'07' ; turn comparators off movwf CMCON ; this makes all Ports digital bsf STATUS, RP0 ; select bank 1 movlw b'00000000' ; set PORTB all outputs movwf TRISB ; movlw b'00100000' ; set PORTA all outputs except for bit 5 movwf TRISA ; remember bit 5 cannot be made an output! bcf STATUS, RP0 ; select bank 0 setup movlw b'11011010' ; This disables all 74373 outputs, and closes movwf PORTA ; all 74373 latches. movlw b'11000000' ; player paddle start position movwf player_1_paddle ; (starts up the top of the screen movlw b'10000000' ; sets the balls start position movwf ball_x ; which is the the top right movwf ball_y ; hand corner of the screen clrf ball_up ; clear the ball up flag clrf ball_down ; clear the ball down flag clrf ball_left ; clear the ball left flag clrf ball_right ; clear the ball right flag bsf ball_down, 0 ; lets start the game off by making the bsf ball_left, 0 ; ball move down and to the left movlw d'50' ; this sets the ball speed movwf ball_refresh ; (the higher the number, the slower the ball speed.) clrf stop_repeat ; clear the stop repeat flag (used in the button repeat rate routine movlw d'30' ; set our button response delay (the higher the number, movwf button_adjust ; the longer you have to wait to be able to push the button again) begin ; lets begin our program! call check_ball ; call the check ball routine call draw_ball ; call the draw ball routine call joystick ; call the joystick routine (see if any buttons have been pressed) call draw_paddle ; call the draw_dot routine (to place the x and y coordinates on the display) call move_ball ; call the draw ball routine btfsc stop_repeat, 1 ; Check to see if the stop repeat bit 1 has been set, call button_time ; if it has, then call the button_time routine (which will decrement the timer by one) goto begin ; do it all again! check_ball ; btfss ball_x, 1 ; first we need to see if the ball is next to our paddle column goto check_next ; if it is NOT then goto check_next, but if it is - movf player_1_paddle, w ; then check if the ball is going to hit the paddle andwf ball_y, w ; if it is going to hit the paddle then btfss STATUS, Z ; make the ball go to the right call set_right ; (to the right) if not, then continue check_next btfsc ball_y, 7 ; now check to see if the ball has hit the screen top call set_down ; if it has then call set down, otherwise - btfsc ball_y, 0 ; check to see if we have hit the screen bottom call set_up ; if it has then call set up, otherwise - btfsc ball_x, 0 ; check to see if the ball has gone past our paddle goto setup ; if it has then goto setup otherwise - btfsc ball_x, 7 ; check to see if we have hit the right hand wall call set_left ; if we have then call set left. return ; and now return to our main program move_ball ; This routine takes care of actually moving the ball decfsz ball_refresh, f ; decrement ball refresh by one, if it is zero return ; then return (dont let the ball move) otherwise - movlw d'50' ; now reset our ball refresh data movwf ball_refresh ; this defines how fast our ball will move. btfsc ball_up, 0 ; is the ball up flag set? rlf ball_y, f ; if yes then move the ball up one space, otherwise btfsc ball_down, 0 ; is the ball down flag set? rrf ball_y, f ; if yes then move the ball down one space, otherwise btfsc ball_left, 0 ; is the ball left flag set? rrf ball_x, f ; if yes then move the ball left one space, otherwise btfsc ball_right, 0 ; is the ball right flag set? rlf ball_x, f ; if yes then move the ball right one space, otherwise return ; now return to where we came from set_up ; this routine sets our up flag bcf ball_down, 0 ; clear the down flag bsf ball_up, 0 ; set the up flag return ; and return set_down ; this routine sets our down flag bcf ball_up, 0 ; clear the up flag bsf ball_down, 0 ; set the down flag return ; and return set_left ; this routine sets our left flag bcf ball_right, 0 ; clear the right flag bsf ball_left, 0 ; set the left flag return ; and return set_right ; this routine sets our right flag bcf ball_left, 0 ; clear the left flag bsf ball_right, 0 ; set the right flag return ; and return draw_ball ; this routine draws the ball on the screen movf ball_y, w ; copy our ball_y co-ordinate to w movwf PORTB ; and then to portb (our data bus) bsf PORTA, 2 ; now latch this 8-bits to the green 74373 bcf PORTA, 2 ; and now close the latches movf ball_x, w ; copy ball_x co-ordinate to w movwf PORTB ; then to port b (our data bus) bsf PORTA, 4 ; now latch this 8-bits to the COLUMN data 74373 bcf PORTA, 4 ; and close the latches bcf PORTA, 3 ; enable both the green and column 74373 outputs bcf PORTA, 6 ; 3 is green and 6 is column data call delay ; hold this data on the screen for a split second bsf PORTA, 3 ; close both green and column outputs bsf PORTA, 6 ; 3 is green and 6 is column data return ; and return to the main program draw_paddle ; This will draw our paddle on the screen movf player_1_paddle, w ; copy the data from player_1_paddle movwf PORTB ; then output that to PORTB bsf PORTA, 0 ; now that its in PORTB, we want to latch that data to the red 74373 bcf PORTA, 0 ; close the latches and now that data will be held there movlw b'00000001' ; This just activates the movwf PORTB ; then place it on PORTB bsf PORTA, 4 ; now latch that data to the COLUMN data 74373 bcf PORTA, 4 ; close the latches and the data will now be held there bcf PORTA, 1 ; now that all our data is ready, we need to enable the outputs bcf PORTA, 6 ; PORTA, 3 is the green 74373 output, and PORTA, 6 is the COLUMN data output call delay ; call the delay, to hold this data on the screen for a split second bsf PORTA, 1 ; now disable both the green 74373 output and also bsf PORTA, 6 ; the COLUMN data 74373 output return ; then return from where we came from ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; ; ; If you recall the way the buttons are working I.E they are ; ; constantly being pulled upto a logic 1 (+5v) but when we ; ; press a button, we now connect that resistor to ground which ; ; means the resitor will drop +5v, but since our output is ; ; connected to the bottom (ground) lead of the resistor, we will ; ; now output a logic 0. So a logic 1 means the button has not ; ; pressed, and a logic 0 means the button has been pressed. ; ; ; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; joystick ; The joystick routine. call port_b_input ; First we need PORTB to be an input before we can read data from the joystick bcf PORTA, 7 ; Now open up the joystick 74373 latches (to allow data through from the buttons) btfss PORTB, 0 ; check the up button, if it has not been pressed (logic 1) then skip this next line, call p1_up ; if it has been pressed (logic 0) then call the up routine btfss PORTB, 1 ; check the down button, if it has not been pressed (logic 1) then skip this next line, call p1_down ; if it has been pressed (logic 0) then call the down routine bsf PORTA, 7 ; Now close the joystick 74373 latches call port_b_output ; Make PORTB an output again so we can then output our data to the screen return ; And return to where we came from... port_b_input ; This routine makes all of PORTB into inputs bsf STATUS, RP0 ; which allows us to then read from the movlw b'11111111' ; Joystick. movwf TRISB ; bcf STATUS, RP0 ; return ; Now return to where we can from... port_b_output ; This routine makes all of PORTB outputs again bsf STATUS, RP0 ; If we didnt make PORTB an output again, then movlw b'00000000' ; we could never display any data on our screen! movwf TRISB ; bcf STATUS, RP0 ; return ; Now return to where we can from... p1_up btfsc player_1_paddle, 7 ; this prevents the paddle from moving return ; off the screen btfsc stop_repeat, 0 ; First we check if the stop_repeat bit is set return ; if it is then return, otherwise - rlf player_1_paddle, 1 ; shift the data in y_coordinate left (this moves the led up) bsf stop_repeat, 1 ; Now that we have moved one space we want to prevent our bsf stop_repeat, 0 ; paddle from moving another space straight away. so we set movf button_adjust, w ; the stop_repeat bits which will remain set untill the movwf button_timer ; specified time period is complete. Without this, the paddle return ; would move way to fast for us to be able to play the game p1_down btfsc player_1_paddle, 0 ; this prevents the paddle from moving return ; off the screen btfsc stop_repeat, 0 ; First we check if the stop_repeat bit is set return ; if it is then return, otherwise - rrf player_1_paddle, 1 ; shift the data in y_coordinate right (this moves the led down) bsf stop_repeat, 1 ; Now that we have moved one space we want to prevent our bsf stop_repeat, 0 ; paddle from moving another space straight away. so we set movf button_adjust, w ; the stop_repeat bits which will remain set untill the movwf button_timer ; specified time period is complete. Without this, the paddle return ; would move way to fast for us to be able to play the game button_time ; This routine decrements the button_timer by one decfsz button_timer, 1 ; (we can change the value of button_timer in the setup routine) return ; If the timer has not yet reached zero, then it returns to the main program bcf stop_repeat ,0 ; If the timer has reached zero, then we clear the stop_repeat bits bcf stop_repeat, 1 ; this then allows us to press a button again! return delay movlw d'03' ; You can make the delay longer by movwf counta ; increasing the decimal value. Or you movwf countb ; can make the delay shorter by decreasing again decfsz counta, 1 ; the decimal value. goto again ; decfsz countb, 1 ; goto again ; once counta and countb have reached zero return ; it will return to the main program end ; thats it!