PIC12F683-based electronic die
How it works.
The PIC runs at 8 MHz using the internal oscillator
and TMR2 increments every 500 ns (it runs as fast
as possible,prescaler=1, postscaler= 1). When the
button is pressed, TMR2 is read and tha value is stored
in a register. Then a number from 1 to 6 is calculated by a
simple routine (with a high-level language you would simply
calculate the reminder after division by 6, plus 1). LEDs are
lit accordingly, till the button is pressed.
The numbers can be considered reasonably
random. Note that the PIR2 register is loaded with 251 (0xFB)
to ensure that the six numbers have equal probability.
 Schematic
(png)
Part list
(txt)
Low-res video (mpg)
; ---------------------------------------------
; Schematic: http://www.eeng.biz/files/edie.png
; Part list: http://www.eeng.biz/files/edie.txt
; Picture: http://www.eeng.biz/files/edie.jpg
; Video: http://www.eeng.biz/files/edie.mpg
; ---------------------------------------------
; Revision: July 25th, 2007
; ---------------------------------------------
list p=12F683
include "p12F683.inc"
__CONFIG _INTOSCIO & _MCLRE_OFF & _FCMEM_OFF & _IESO_OFF & _WDT_OFF & _CP_OFF & _CPD_OFF & _PWRTE_ON & _BOD_OFF cblock 0x20
v1
v2
d1
d2
endc org 0x000
Start
movlw 0x3F
movwf GPIO movlw 0x07
movwf CMCON0 ;turn comparators off
bsf STATUS,RP0 ;bank 1
clrf ANSEL
movlw b'011000' ;GPIO0,1,2,5 as outputs
movwf TRISIO ;GPIO4 as input
movlw b'00010000' ;pull-up resistor on GPIO4
movwf WPU
movlw b'00001000' ;pull-up resistor enabled
movwf OPTION_REG
movlw 0xFB ;251
movwf PR2
movwf b'01110001' ;8 MHz
movwf OSCCON
Osctest
btfss OSCCON, HTS ;oscillator stable?
goto Osctest
bcf STATUS,RP0 ;bank 0
movlw b'00000100' ;enable TMR2
movwf T2CON
Main
btfss GPIO, 4 ;switch pressed?
call B0
movlw 0x3F
movwf GPIO ;LEDs off
goto Main B0
movf TMR2, w ;read TMR2
movwf v1
movwf v2
call Delay20m ;simple debounce
btfsc GPIO, 4 ;still pressed?
return
B1
movlw 0x06
subwf v1, w ;v1-6 -> W
btfss STATUS, C ;if C=0 goto B2
goto B2
movwf v1
movwf v2
goto B1 B2
;1<= v2 <=6
movf v2, w
call Table
movwf GPIO ;turn LEDs on
B3
btfsc GPIO, 4 ;still pressed?
return
goto B3
Table
ADDWF PCL, f
retlw 0x07
retlw 0x23
retlw 0x03
retlw 0x21
retlw 0x01
retlw 0x20
Delay20m ;about 20 ms
movlw 0x3E
movwf d1
movlw 0x20
movwf d2
Delay20_1
decfsz d1, f
goto $+2
decfsz d2, f
goto Delay20_1 return end
Enjoy building your PIC-based electronic dice! |
