Autonomous Vehicle Project

I and my two lab partners spent about three weeks programming a PICchip, in assembly language, to move this truck in an oval and have it return to the spot it started at. We used pulse width modulation, interrupts and a lot of tweaking of timing to make it loop and return to the same spot.

Something we noticed during our trials was that the truck ran at different speeds depending on how long it had been running for. When we realized that warming our truck up first would give more consistent results, we began warming it up before each test.

Bubble Sort in Assembly Language

Here's a homework assignment where I had to implement a bubble sort in Assembly Language. My professor gave us specific values to put into the first 8 data memory locations, then we had to sort those values and keep them all in those first 8 spaces in memory.
I love this code. Very simple, clean and best of all, it works!

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

;FILE: main.asm

;DESC HW9

;Date: 3-10-2014

;Device: PIC18F1220

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

                list p=18F1220

                radix hex

                config WDT=OFF, LVP=OFF

#include P18F1220.INC

I equ 0x50                                    ;make I register (somewhere out of the way)

INEXT equ 0x52                                ;make INEXT register (somewhere out of the way)

TEMP equ 0x54                                 ;make TEMP register (somewhere out of the way)

                MOVLW 0X00                    ;put 0 into WREG

                MOVWF FSR0L                   ;inititalize FSR0L to 0

                MOVWF INDF0                   ;initialize INDF0 to 0

                MOVWF I                       ;initialize I to 0

                MOVWF INEXT                   ;initialize INEXT to 0        

               

                                                                                                ;initialize locations 0x00-0x07 with numbers from assignment description

                MOVLW d'10'    

                MOVWF INDF0                    ;put decimal 10 into location 0

               

                INCF FSR0L                     ;FRS0=1. Location of INDF0=1

                MOVLW d'16'    

                MOVWF INDF0                    ;put decimal 16 into location 1

                INCF FSR0L                     ;FRS0=2. Location of INDF0=2

                MOVLW d'1'

                MOVWF INDF0                    ;put decimal 1 into location 2

                INCF FSR0L                     ;FRS0=3. Location of INDF0=3

                MOVLW d'5'

                MOVWF INDF0                    ;put decimal 5 into location 3

                INCF FSR0L                     ;FRS0=4. Location of INDF0=4

                MOVLW d'15'

                MOVWF INDF0                    ;put decimal 15 into location 4

                INCF FSR0L                     ;FRS0=5. Location of INDF0=5

                MOVLW d'11'

                MOVWF INDF0                    ;put decimal 11 into location 5

                INCF FSR0L                     ;FRS0=6. Location of INDF0=6

                MOVLW d'2'

                MOVWF INDF0                    ;put decimal 2 into location 6

                INCF FSR0L                     ;FRS0=7. Location of INDF0=7

                MOVLW d'6'

                MOVWF INDF0                    ;put decimal 6 into location 7

mainloop:

                MOVLW 0X01

                MOVWF FSR0L                    ;FSR0L is set to 1 so that bubble                                                ;loop will start at location 0

                BRA bubble

endloop:

                BRA endloop                    ;will probably never be reached...

switch:                                        ;will be accessed if two numbers                                                  ;need to be switched int he array

                MOVFF I, TEMP                  ;move contents of I into TEMP register

                MOVFF INEXT, I                 ;move contents of INEXT into I

                MOVFF TEMP, INEXT              ;move contents of TEMP into INEXT

                                                                                                                                 ;so now I is INEXT and INEXT is I

                DECF FSR0L                     ;go back one space in memory

                MOVFF I, INDF0                 ;put I into location of FSR0

                INCF FSR0L                     ;go to next location

                MOVFF INEXT, INDF0             ;put INEXT into next location of FSR0

                INCF FSR0L         

                MOVLW d'7'

                SUBWF FSR0L,W                  ;subtract 7 from FSR0L and store in WREG

                BNN mainloop                   ;if FSR0L>7, start new pass 
                                               ;(branch to mainloop

bubble:

                DECF FSR0L                     ;take FSR0 back one spot

                MOVFF INDF0, I                 ;move 10 into I register

                INCF FSR0L                     ;FSR0L is now 1. So looking at                                                    ;location 1 where 16 sits

                MOVFF INDF0, INEXT             ;move 16 into INEXT register

                                                                                                                                 ;compare I and INEXT

                MOVF I, W                      ;put value of I into WREG

                SUBWF INEXT, W                 ;subtract WREG(I) from INEXT

                BN switch                      ;if I>INEXT, branch to switch loop

                INCF FSR0L                     ;increment FSR0 so that the next                                                  ;loop will be looking at the next                                                ;location

                BRA bubble                     

                end