void delay2( uint us) {
while( us － － ) ; }
uchar Init_DS18B20( void) {
uchar x =0; DQ = 1; delay2( 8) ; DQ = 0; delay2( 80) ; DQ = 1; delay2( 10) ; x = DQ; delay2( 5) ;
return x; } … … … …
/＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊ ＊DS18b20 读取主函数，整个流程5ms 左右＊＊＊＊＊ ＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊/ uchar ReadTemperature( void) {
uchar L_18B20 =0; uchar H_18B20 =0; Init_DS18B20( ) ; WriteOneChar( 0xCC) ; WriteOneChar( 0x44) ; delay2( 200) ;
Init_DS18B20( ) ; WriteOneChar( 0xCC) ; WriteOneChar( 0xBE) ; L_18B20 = ReadOneChar( ) ; H_18B20 = ReadOneChar( ) ; if( H_18B20 ＞0x7f) {
L_18B20 = ～ L_18B20 +1; H_18B20 = ～ H_18B20; fg =1; } … … … …
( 2) 湿度采集
SAMPLE: SETB 00H; MOV DPTR， #0F00H;
MOV R6， #02H; MOV R7， #08H; MOV R0， #40H;
TRAN_S: MOVX @ DPTR，A; WAIT: JB 00H，WAIT; SETB 00H; INC DPTR; INC R0 INC R0; … … … …
/ /＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊ ＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊ ＊＊＊＊＊＊＊＊＊/ /
即将0809 传来的二进制数转换为BCD 编码，由于
待转换的二制数不大于255，因此利用字节除法来实现 / /＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊ ＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊ ＊＊＊＊＊＊＊＊＊/ / MOV B， #100 DIV AB; MOV R2，A;
MOV A，B; MOV B， #10DIV AB; SWAP A; … … … …
