;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; ; ; PIC Microcontroller Tutorial Module 5 ; ; ; ; By Brad Slattery 2009 ; ; www.bradsprojects.com ; ; brad@bradsprojects.com ; ; ; ; 'Designing electronic projects, ; ; to spread the name of Jesus' ; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; ; ; NOTE: If you are brand new to programming, then don't concern yourself to ; ; much with all of these initial lines of code. You can read up all about this ; ; at a later date if you wish. I'm sure that you would rather make an LED flash ; ; or make something interesting happen straight away right? ; ; All you have to know for now is that we will be placing our code just underneath ; ; the SETUP label, and then underneath the BEGIN label. it's really quite simple! ; ; ; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; LIST p=16f648a ; tell assembler what chip we are using (if you are using the 16f628a, then include "P16f648a.inc" ; make sure you change this line and the previous line to read p16f628a __config h'3f18' ; sets the configuration settings - internal oscillator, watchdog timer OFF ; Power Up Timer DISABLED, Master Clear DISABLED, Brown Out Detect DISABLED, ; Low Voltage Programming DISABLED, Data EE Read Protect Disabled, ; Code Protect OFF. (this will remain the same for all tutorials) PC equ h'02' ; The program counter will be refered to as PC - The program counter is ; a little counter within the microcontroller to let itself know what line number ; it is upto when running a program. We can make the microcontroller jump to a certain ; line number by changing the value stored in PC. (we will do this in a later tutorial) cblock h'20' ; Within this cblock and endc, we can define our variables. More info on this, later. delay_1 ; set aside 1 byte for a variable called delay_1 delay_2 ; set aside 1 byte for a variable called delay_1 data_counter ; set aside 1 byte for a variable called data_counter endc ; that's the end of defining our variables org h'0000' ; This line just tells the microcontroller what address to start running our program from. ; It will always be 0000 hex for all the tutorials. movlw h'07' ; This will turn the comparators OFF. movwf CMCON ; (we just want to use the ports as digital ports) bsf STATUS, RP0 ; select bank 1 (to enable us to change the Input / Output status of our ports) movlw b'00000000' ; set PORTB all outputs (A '0' means output, A '1' means input. We can set each movwf TRISB ; We can set each bit individualy. Each port having 8-bits or 8 pins. movlw b'00100000' ; set PORTA all outputs except for bit 5. Bit 5 is an input ONLY pin. movwf TRISA ; It cannot be set to an output! bcf STATUS, RP0 ; select bank 0 goto setup ; Go straight to the main part of our code. display_data ; This contains data for the different led positions incf data_counter, f ; increment data_counter by one, then movf data_counter, w ; copy the answer to our working register and then, addwf PC ; add this number to our program counter (this just skips one line everytime we come here) nop ; skip one step. retlw b'11101111' ; these next lot of retlw instructions will be sent to retlw b'11101111' ; PORTB to light up one LED at a time in a chasing light pattern. retlw b'11110111' ; once the last LED is lit, then program counter will increment one more retlw b'10111111' ; time but there are no more retlw statements, so it goes back to setup retlw b'10111111' ; (which is underneath all these retlw statements) and starts the pattern again. retlw b'11111110' ; retlw b'11111101' ; retlw b'11111101' ; retlw b'11111011' ; retlw b'10111111' ; retlw b'10111111' ; retlw b'11011111' ; setup ; I always have a title labelled 'setup' this is where we set everything up clrf data_counter ; we want to start at the start so we need to make sure that data_counter contains zero bcf PORTA, 0 ; turn OFF the first display (by disconnecting +5v from the anodes) bcf PORTA, 1 ; turn OFF the second display (by disconnecting +5v from the anodes) begin ; This is where our main program starts. call display_data ; call display data to grab a byte of data which we then movwf PORTB ; send to PORTB for display on a certain screen. bsf PORTA, 1 ; in this case it is the left screen call delay ; call the delay to keep it on for a moment and then bcf PORTA, 1 ; turn the display off call display_data ; call display data to grab a byte of data which we then movwf PORTB ; send to PORTB for display on a certain screen. bsf PORTA, 0 ; in this case it is the right screen call delay ; call the delay to keep it on for a moment and then bcf PORTA, 0 ; turn the display off call display_data ; call display data to grab a byte of data which we then movwf PORTB ; send to PORTB for display on a certain screen. bsf PORTA, 0 ; in this case it is the right screen call delay ; call the delay to keep it on for a moment and then bcf PORTA, 0 ; turn the display off call display_data ; call display data to grab a byte of data which we then movwf PORTB ; send to PORTB for display on a certain screen. bsf PORTA, 0 ; in this case it is the right screen call delay ; call the delay to keep it on for a moment and then bcf PORTA, 0 ; turn the display off call display_data ; call display data to grab a byte of data which we then movwf PORTB ; send to PORTB for display on a certain screen. bsf PORTA, 1 ; in this case it is the left screen call delay ; call the delay to keep it on for a moment and then bcf PORTA, 1 ; turn the display off call display_data ; call display data to grab a byte of data which we then movwf PORTB ; send to PORTB for display on a certain screen. bsf PORTA, 1 ; in this case it is the left screen call delay ; call the delay to keep it on for a moment and then bcf PORTA, 1 ; turn the display off call display_data ; call display data to grab a byte of data which we then movwf PORTB ; send to PORTB for display on a certain screen. bsf PORTA, 1 ; in this case it is the left screen call delay ; call the delay to keep it on for a moment and then bcf PORTA, 1 ; turn the display off call display_data ; call display data to grab a byte of data which we then movwf PORTB ; send to PORTB for display on a certain screen. bsf PORTA, 0 ; in this case it is the right screen call delay ; call the delay to keep it on for a moment and then bcf PORTA, 0 ; turn the display off call display_data ; call display data to grab a byte of data which we then movwf PORTB ; send to PORTB for display on a certain screen. bsf PORTA, 0 ; in this case it is the right screen call delay ; call the delay to keep it on for a moment and then bcf PORTA, 0 ; turn the display off call display_data ; call display data to grab a byte of data which we then movwf PORTB ; send to PORTB for display on a certain screen. bsf PORTA, 0 ; in this case it is the right screen call delay ; call the delay to keep it on for a moment and then bcf PORTA, 0 ; turn the display off call display_data ; call display data to grab a byte of data which we then movwf PORTB ; send to PORTB for display on a certain screen. bsf PORTA, 1 ; in this case it is the left screen call delay ; call the delay to keep it on for a moment and then bcf PORTA, 1 ; turn the display off call display_data ; call display data to grab a byte of data which we then movwf PORTB ; send to PORTB for display on a certain screen. bsf PORTA, 1 ; in this case it is the left screen call delay ; call the delay to keep it on for a moment and then bcf PORTA, 1 ; turn the display off goto begin ; and repeat! delay ; here is a nice and simple delay routine movlw d'100' ; copy the decimal number 100 to the working register movwf delay_1 ; and now copy it from the w register to delay_1 and delay_2 movwf delay_2 ; Now the rest of the routine will focus on counting down to zero. delay_loop ; We come back to this label when we have not yet reached zero. decfsz delay_1, f ; decrement whatever is in delay_1 by 1 and store the answer back in delay_1 goto delay_loop ; if the answer is not zero, then go back to the delay_loop label. but if the decfsz delay_2, f ; answer is zero then decrement delay_2 by one and store the answer in delay_2 goto delay_loop ; if the answer is not zero, then go back to delay_loop label. but if the answer return ; is zero, then we have completed our delay and now we can return to our main program! end ; We always need to have end at the end, even if we don't want the program ; to actually end, it still must be here!