📄 shtxx_sample_code.lst
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622 1 {
623 2 _Nop();
624 2 SCL=0; /*置时钟线为低，准备接收数据位*/
625 2 _Nop();
626 2 _Nop(); /*时钟低电平周期大于4.7μs*/
627 2 _Nop();
628 2 _Nop();
629 2 _Nop();
630 2 SCL=1; /*置时钟线为高使数据线上数据有效*/
631 2 _Nop();
632 2 _Nop();
633 2 retc=retc<<1;
634 2 if(SDA==1)retc=retc+1; /*读数据位,接收的数据位放入retc中 */
635 2 _Nop();
636 2 _Nop();
637 2 }
638 1 SCL=0;
639 1 _Nop();
640 1 _Nop();
641 1 return(retc);
642 1 }
643
644
645 void Ack_I2c(bit a) //主控器进行应答信号
646 {
647 1
648 1 if(a==0)SDA=0; /*在此发出应答或非应答信号 */
649 1 else SDA=1;
650 1 _Nop();
651 1 _Nop();
652 1 _Nop();
653 1 SCL=1;
654 1 _Nop();
655 1 _Nop(); //时钟低电平周期大于4μ
656 1 _Nop();
657 1 _Nop();
658 1 _Nop();
659 1 SCL=0; /*清时钟线，钳住I2C总线以便继续接收*/
660 1 _Nop();
661 1 _Nop();
662 1 }
663 //bit ISendStr(uchar sla,uchar suba,uchar *s,uchar no) //向有子地址器件发送多字节数据函数
664 //子地址为8位的数据传送
665 bit ISendStr_8(uchar add,uchar son_add,uchar dat) //向子地址为8位的器件发送多字节数据函数
666 {
667 1 Start_I2c(); /*启动总线*/
668 1 SendByte(add); /*发送器件地址*/
669 1 if(ack==0)return(0);
670 1 SendByte(son_add); /*发送器件子地址*/
671 1 if(ack==0)return(0);
672 1 SendByte(dat); /*发送数据*/
673 1 if(ack==0)return(0);
C51 COMPILER V7.07 SHTXX_SAMPLE_CODE 04/04/2007 18:18:08 PAGE 12
674 1 Stop_I2c(); /*结束总线*/
675 1 return(1);
676 1 }
677 //子地址为16位的数据传送
678 bit ISendStr_16(uchar add,uint son_add,uchar dat) //向子地址为16位的器件发送多字节数据函数
679 {
680 1 Start_I2c(); /*启动总线*/
681 1 SendByte(add); /*发送器件地址*/
682 1 if(ack==0)return(0);
683 1 SendByte(son_add/256); /*发送器件子地址*/
684 1 if(ack==0)return(0);
685 1 SendByte(son_add%256); /*发送器件子地址*/
686 1 if(ack==0)return(0);
687 1 SendByte(dat); /*发送数据*/
688 1 if(ack==0)return(0);
689 1 Stop_I2c(); /*结束总线*/
690 1 return(1);
691 1 }
692
693
694
695 //bit IRcvStr(uchar sla,uchar suba,uchar *s,uchar no) //向有子地址器件读取多字节数据函数
696 //子地址为8位的数据传送
697 uchar IRcvStr_8(uchar add,uchar son_add) //向子地址为8位的器件读取多字节数据函数
698 {
699 1
700 1 uchar i;
701 1 Start_I2c(); /*启动总线*/
702 1 SendByte(add); /*发送器件地址*/
703 1 SendByte(son_add); /*发送器件子地址2*/
704 1 Start_I2c();
705 1 SendByte(add+0x01);
706 1 i=RcvByte();
707 1 Ack_I2c(1); /*发送非应位*/
708 1 Stop_I2c(); /*结束总线*/
709 1 return (i);
710 1 }
711 //子地址为16位的数据传送
712 uchar IRcvStr_16(uchar add,uint son_add) //向子地址为16位的器件读取多字节数据函数
713 {
714 1
715 1 uchar i;
716 1 Start_I2c(); /*启动总线*/
717 1 SendByte(add); /*发送器件地址*/
718 1 SendByte(son_add/256); /*发送器件子地址1*/
719 1 SendByte(son_add%256); /*发送器件子地址2*/
720 1 Start_I2c();
721 1 SendByte(add+0x01);
722 1 i=RcvByte();
723 1 Ack_I2c(1); /*发送非应位*/
724 1 Stop_I2c(); /*结束总线*/
725 1 return (i);
726 1 }
727
728
729 //----------------------------------------------------------------------------------
730 char s_write_byte(unsigned char value)
731 //----------------------------------------------------------------------------------
732 // writes a byte on the Sensibus and checks the acknowledge
733 {
734 1 unsigned char i,error=0;
735 1 for (i=0x80;i>0;i/=2) //shift bit for masking
C51 COMPILER V7.07 SHTXX_SAMPLE_CODE 04/04/2007 18:18:08 PAGE 13
736 1 { if (i & value) DATA=1; //masking value with i , write to SENSI-BUS
737 2 else DATA=0;
738 2 SCK=1; //clk for SENSI-BUS
739 2 _nop_();_nop_();_nop_(); //pulswith approx. 5 us
740 2 SCK=0;
741 2 }
742 1 DATA=1; //release DATA-line
743 1 SCK=1; //clk #9 for ack
744 1 error=DATA; //check ack (DATA will be pulled down by SHT11)
745 1 SCK=0;
746 1 return error; //error=1 in case of no acknowledge
747 1 }
748
749 //----------------------------------------------------------------------------------
750 char s_read_byte(unsigned char ack)
751 //----------------------------------------------------------------------------------
752 // reads a byte form the Sensibus and gives an acknowledge in case of "ack=1"
753 {
754 1 unsigned char i,val=0;
755 1 DATA=1; //release DATA-line
756 1 for (i=0x80;i>0;i/=2) //shift bit for masking
757 1 { SCK=1; //clk for SENSI-BUS
758 2 if (DATA) val=(val | i); //read bit
759 2 SCK=0;
760 2 }
761 1 DATA=!ack; //in case of "ack==1" pull down DATA-Line
762 1 SCK=1; //clk #9 for ack
763 1 _nop_();_nop_();_nop_(); //pulswith approx. 5 us
764 1 SCK=0;
765 1 DATA=1; //release DATA-line
766 1 return val;
767 1 }
768
769 //----------------------------------------------------------------------------------
770 void s_transstart(void)
771 //----------------------------------------------------------------------------------
772 // generates a transmission start
773 // _____ ________
774 // DATA: |_______|
775 // ___ ___
776 // SCK : ___| |___| |______
777 {
778 1 DATA=1; SCK=0; //Initial state
779 1 _nop_();
780 1 SCK=1;
781 1 _nop_();
782 1 DATA=0;
783 1 _nop_();
784 1 SCK=0;
785 1 _nop_();_nop_();_nop_();
786 1 SCK=1;
787 1 _nop_();
788 1 DATA=1;
789 1 _nop_();
790 1 SCK=0;
791 1 }
792
793 //----------------------------------------------------------------------------------
794 void s_connectionreset(void)
795 //----------------------------------------------------------------------------------
796 // communication reset: DATA-line=1 and at least 9 SCK cycles followed by transstart
797 // _____________________________________________________ ________
C51 COMPILER V7.07 SHTXX_SAMPLE_CODE 04/04/2007 18:18:08 PAGE 14
798 // DATA: |_______|
799 // _ _ _ _ _ _ _ _ _ ___ ___
800 // SCK : __| |__| |__| |__| |__| |__| |__| |__| |__| |______| |___| |______
801 {
802 1 unsigned char i;
803 1 DATA=1; SCK=0; //Initial state
804 1 for(i=0;i<9;i++) //9 SCK cycles
805 1 { SCK=1;
806 2 SCK=0;
807 2 }
808 1 s_transstart(); //transmission start
809 1 }
810
811 //----------------------------------------------------------------------------------
812 char s_softreset(void)
813 //----------------------------------------------------------------------------------
814 // resets the sensor by a softreset
815 {
816 1 unsigned char error=0;
817 1 s_connectionreset(); //reset communication
818 1 error+=s_write_byte(RESET); //send RESET-command to sensor
819 1 return error; //error=1 in case of no response form the sensor
820 1 }
821
822 //----------------------------------------------------------------------------------
823 char s_read_statusreg(unsigned char *p_value, unsigned char *p_checksum)
824 //----------------------------------------------------------------------------------
825 // reads the status register with checksum (8-bit)
826 {
827 1 unsigned char error=0;
828 1 s_transstart(); //transmission start
829 1 error=s_write_byte(STATUS_REG_R); //send command to sensor
830 1 *p_value=s_read_byte(ACK); //read status register (8-bit)
831 1 *p_checksum=s_read_byte(noACK); //read checksum (8-bit)
832 1 return error; //error=1 in case of no response form the sensor
833 1 }
834
835 //----------------------------------------------------------------------------------
836 char s_write_statusreg(unsigned char *p_value)
837 //----------------------------------------------------------------------------------
838 // writes the status register with checksum (8-bit)
839 {
840 1 unsigned char error=0;
841 1 s_transstart(); //transmission start
842 1 error+=s_write_byte(STATUS_REG_W);//send command to sensor
843 1 error+=s_write_byte(*p_value); //send value of status register
844 1 return error; //error>=1 in case of no response form the sensor
845 1 }
846
847 //----------------------------------------------------------------------------------
848 char s_measure(unsigned char *p_value, unsigned char *p_checksum, unsigned char mode)
849 //----------------------------------------------------------------------------------
850 // makes a measurement (humidity/temperature) with checksum
851 {
852 1 unsigned error=0;
853 1 unsigned int i;
854 1
855 1 s_transstart(); //transmission start
856 1 switch(mode){ //send command to sensor
857 2 case TEMP : error+=s_write_byte(MEASURE_TEMP); break;
858 2 case HUMI : error+=s_write_byte(MEASURE_HUMI); break;
859 2 default : break;
C51 COMPILER V7.07 SHTXX_SAMPLE_CODE 04/04/2007 18:18:08 PAGE 15
860 2 }
861 1 for (i=0;i<65535;i++) if(DATA==0) break; //wait until sensor has finished the measurement
862 1 if(DATA) error+=1; // or timeout (~2 sec.) is reached
863 1 *(p_value) =s_read_byte(ACK); //read the first byte (MSB)
864 1 *(p_value+1)=s_read_byte(ACK); //read the second byte (LSB)
865 1 *p_checksum =s_read_byte(noACK); //read checksum
866 1 return error;
867 1 }
868
869 //----------------------------------------------------------------------------------
870 void init_uart()
871 //----------------------------------------------------------------------------------
872 //9600 bps @ 11.059 MHz
873 {SCON = 0x52;
874 1 TMOD = 0x20;
875 1 TCON = 0x69;
876 1 TH1 = 0xfd;
877 1 }
878
879 //----------------------------------------------------------------------------------------
880 void calc_sth11(float *p_humidity ,float *p_temperature)
881 //----------------------------------------------------------------------------------------
882 // calculates temperature [癈] and humidity [%RH]
883 // input : humi [Ticks] (12 bit)
884 // temp [Ticks] (14 bit)
885 // output: humi [%RH]
886 // temp [癈]
887 { const float C1=-4.0; // for 12 Bit
888 1 const float C2=+0.0405; // for 12 Bit
889 1 const float C3=-0.0000028; // for 12 Bit
890 1 const float T1=+0.01; // for 14 Bit @ 5V
891 1 const float T2=+0.00008; // for 14 Bit @ 5V
892 1
893 1 float rh=*p_humidity; // rh: Humidity [Ticks] 12 Bit
894 1 float t=*p_temperature; // t: Temperature [Ticks] 14 Bit
895 1 float rh_lin; // rh_lin: Humidity linear
896 1 float rh_true; // rh_true: Temperature compensated humidity
897 1 float t_C; // t_C : Temperature [癈]
898 1
899 1 t_C=t*0.01 - 40; //calc. temperature from ticks to [癈]
900 1 rh_lin=C3*rh*rh + C2*rh + C1; //calc. humidity from ticks to [%RH]
901 1 rh_true=(t_C-25)*(T1+T2*rh)+rh_lin; //calc. temperature compensated humidity [%RH]
902 1 if(rh_true>100)rh_true=100; //cut if the value is outside of
903 1 if(rh_true<0.1)rh_true=0.1; //the physical possible range
904 1
905 1 *p_temperature=t_C; //return temperature [癈]
906 1 *p_humidity=rh_true; //return humidity[%RH]
907 1 }
908
909 //--------------------------------------------------------------------
910 float calc_dewpoint(float h,float t)
911 //--------------------------------------------------------------------
912 // calculates dew point
913 // input: humidity [%RH], temperature [癈]
914 // output: dew point [癈]
915 { float logEx,dew_point;
916 1 logEx=0.66077+7.5*t/(237.3+t)+(log10(h)-2);
917 1 dew_point = (logEx - 0.66077)*237.3/(0.66077+7.5-logEx);
918 1 return dew_point;
919 1 }
920
921 //----------------------------------------------------------------------------------
C51 COMPILER V7.07 SHTXX_SAMPLE_CODE 04/04/2007 18:18:08 PAGE 16
922 void main()
923 //----------------------------------------------------------------------------------
924 // sample program that shows how to use SHT11 functions
925 // 1. connection reset
926 // 2. measure humidity [ticks](12 bit) and temperature [ticks](14 bit)
927 // 3. calculate humidity [%RH] and temperature [癈]
928 // 4. calculate dew point [癈]
929 // 5. print temperature, humidity, dew point
930
931 {
932 1
933 1 uchar i = 0;
934 1 uchar v = 0;
935 1 uchar keydata = 0;
936 1 uint dat_ad = 0;
937 1 uchar num_ad = 0;
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