btfss IRin ; if the last bit was a high-low sequence, immediately set IRin
bsf IRin ; high to terminate the RC5 code after the correct time
call delay_t6 ; 250ms delay for time decoupling (IR codes from the receiver chip
; occuring directly after the code generated above would destroy
; the integrity of this code)
Bank_1
bsf IRinTris ; set IRin to input again
Bank_0
return
;**************************************************************************************************
; RC5 receive routine
;**************************************************************************************************
;
; in: 14 bit data from IRin resp. DTRin
;
; out: RC5_ADR (8 bit, 000AAAAA)
; RC5_CMD (8 bit, TCCCCCCC)
; RC5_Flag (1 bit) 0: RC5 code valid, 1: RC5 code invalid
;
; Self-synchronizing code which tolerates inaccurate RC5 timings.
; Tolerance is achieved by polling +/- approx. 250祍 around each expected level change. To mark the
; received code as valid, the level before and after the edges must be opposite, no timer0 overflow
; (512祍) occurred, and two samples taken at 1200祍 and 1500祍 after each edge must be equal.
rc5_rx
clrf DATA_1 ; clear input shift register
clrf DATA_2 ;
MOVlw d’13’ ; set BITCOUNT to 13
MOVwf BITCOUNT ;
test ; 1祍 mark
call delay_t1a ; 1520祍 delay until approx. 256 祍 before next expected slope
call delay_t1b
pre_slope
test ; 1祍 mark
clrf tmr0 ; clear timer0 register
bcf iNTCon,t0if ; clear timer0 interrupt flag
btfss IR_C_out ; IR_C_out high?
goto poll_lo_hi ;
poll_hi_lo
btfsc intcon,t0if ; check for timer0 overflow (after 512祍)
goto set_flag ; and set ’invalid’ flag
btfsc IR_C_out
goto poll_hi_lo
goto next_bit1
poll_lo_hi
bsf DATA_1,0 ; set lsb in DATA_1
btfsc intcon,t0if ; check for timer0 overflow (after 512祍)
goto set_flag ; and set ’invalid’ flag
btfss IR_C_out
goto poll_lo_hi
next_bit1
decfsz BITCOUNT,1 ; if 0: all 14 bits received (1st was used for
goto shift ; trigger and has not been recorded); do not
goto cleanup ; shift any further and go on with cleanup
shift
bcf status,c ; clear carry bit
rlf DATA_1,1 ; left shift the 16-bit register DATA_2/DATA_1
rlf DATA_2,1 ;
call delay_t1a ; aquire sample #1
clrf DATA_TMP1 ; clear temporary register
btfss IR_C_out ; IR_C_out low?
bsf DATA_TMP1,0 ; then set lsb in DATA_TMP1
call delay_t1b ; aquire sample #2
clrf DATA_TMP2 ; clear temporary register
btfss IR_C_out ; IR_C_out low?
bsf DATA_TMP2,0 ; then set lsb in DATA_TMP2
check ; check if samples are equal
MOVfw DATA_TMP1 ; copy DATA_1 to w,
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本文关键字：程序 PIC单片机，单片机-工控设备 - PIC单片机
