;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; ; ; PIC Microcontroller Tutorial Template ; ; ; ; 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 ; These next two lines will set aside 1byte of ram for delay_1 and 1byte for delay_2 delay_2 ; what we will do with these variables is load them with a number each so that we can endc ; count down from that number to zero. when we reach zero, we continue with the program! ; more info on these two variables can be found in the delay routine. 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 setup ; I always have a title labeled 'setup' this is where we set everything up clrf PORTB ; Turn all LEDs connected to PORTB OFF ; i.e. our variables and flags etc.. so they are ready for the main program begin ; This is where our main program starts. movlw b'00000001' ; move binary value 00000001 to the working register movwf PORTB ; then send it to PORTB. Now the LED on the right will be ON call delay ; call the delay to hold the LED ON for just a moment movlw b'00000010' ; move binary value 00000010 to the working register movwf PORTB ; then send it to PORTB. Now the LED second from the right will be ON call delay ; call the delay to hold the LED ON for just a moment movlw b'00000100' ; move binary value 00000100 to the working register movwf PORTB ; then send it to PORTB. Now the LED third from the right will be ON call delay ; call the delay to hold the LED ON for just a moment movlw b'00001000' ; move binary value 00001000 to the working register movwf PORTB ; then send it to PORTB. Now the LED fourth from the right will be ON call delay ; call the delay to hold the LED ON for just a moment movlw b'00010000' ; move binary value 00010000 to the working register movwf PORTB ; then send it to PORTB. Now the LED fifth from the right will be ON call delay ; call the delay to hold the LED ON for just a moment movlw b'00100000' ; move binary value 00100000 to the working register movwf PORTB ; then send it to PORTB. Now the LED sixth from the right will be ON call delay ; call the delay to hold the LED ON for just a moment movlw b'01000000' ; move binary value 01000000 to the working register movwf PORTB ; then send it to PORTB. Now the LED seventh from the right will be ON call delay ; call the delay to hold the LED ON for just a moment movlw b'10000000' ; move binary value 10000000 to the working register movwf PORTB ; then send it to PORTB. Now the LED eighth from the right will be ON call delay ; call the delay to hold the LED ON for just a moment movlw b'01000000' ; move binary value 01000000 to the working register movwf PORTB ; then send it to PORTB. Now the LED seventh from the right will be ON call delay ; call the delay to hold the LED ON for just a moment movlw b'00100000' ; move binary value 00100000 to the working register movwf PORTB ; then send it to PORTB. Now the LED sixth from the right will be ON call delay ; call the delay to hold the LED ON for just a moment movlw b'00010000' ; move binary value 00010000 to the working register movwf PORTB ; then send it to PORTB. Now the LED fifth from the right will be ON call delay ; call the delay to hold the LED ON for just a moment movlw b'00001000' ; move binary value 00001000 to the working register movwf PORTB ; then send it to PORTB. Now the LED fourth from the right will be ON call delay ; call the delay to hold the LED ON for just a moment movlw b'00000100' ; move binary value 00000100 to the working register movwf PORTB ; then send it to PORTB. Now the LED third from the right will be ON call delay ; call the delay to hold the LED ON for just a moment movlw b'00000010' ; move binary value 00000010 to the working register movwf PORTB ; then send it to PORTB. Now the LED second from the right will be ON call delay ; call the delay to hold the LED ON for just a moment goto begin ; and now go and do it all again (it will run in a continuous loop) delay ; here is a nice and simple delay routine movlw d'100' ; copy the maximum number to our working register (decimal 255) 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!