三星程序样例

各位此程序仅供产考 有什么不对的地方请高手指教:sht10-spi.

; P1.3 = CS, OUTPUT  
; P1.4 = SCK, INPUT
; P1.5 = DAT, INPUT
; P1.6 = Reset, OUTPUT
;
; after call read_mth01, register "flag.0=1 means read data sucessful, =0 means read data error"
;
; cnt_2hz is counter for 0.5s, increment 1 every half sec in interruption subroutine.
;
; fskram is the buffer for data shifted in

read_mth01
 and flag,#0feh  ; reset ok bit
 ld r1,cnt_2hz
 ld r0,#32   ; prepare to shift in 4 bytes
 and P1,#0f7h  ; cs low
rmth00 cp r1,cnt_2hz
 jr nz,rmth10 
 tm P1,#10h   ; waite until sclk goes high
 jr z,rmth00
 scf 
 tm p1,#20h
 jr nz,rmth01
 rcf
rmth01 rlc fskram+3  ; read sdat value
 rlc fskram+2
 rlc fskram+1
 rlc fskram
rmth02 cp r1,cnt_2hz
 jr nz,rmth10
 tm p1,#10h
 jr nz,rmth02  ; waite until the clock is low 
 dec r0
 jr nz,rmth00
 or flag,#01h  ; set ok bit after sucessful received 
rmth03 or P1,#08h   ; cs high
 ret
 ;
rmth10 and P1,#0bfh  ; reset low
 ld r1,#30
.extern DelayNN 
 call DelayNN   ; delay 20ms
 or P1,#40h
 jr rmth03
;

出

;
 .end