AM2320 temperature and Humidity sensor C51 program UART serial output temperature and humidity

Physical map

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Pin diagram

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Wiring diagram

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source code

Am Series temperature and humidity sensor, read IIC Use example  //microcontroller   :at89s52  or  stc89c52rc //function   : Serial send temperature and humidity data    baud rate  9600 //Crystal    :12m  (user system clock if not 12m  please change the relevant macro definition and comment delay time)//Baud rate: 9600//compilation environment:   keil 4//********************** #include   "reg52.h" #include  <intrins.h> #define  USE_T2  #define &NBSP;FOSC&NBSP;&NBSP;12000000#DEFINE&NBSP;BAUD&NBSP;&NBSP;9600//Port bit definition, can be modified sbit  sda=p1^0;sbit scl=p1^1;//internal data definition #define iic_add 0xb8    //device address #define  iic_rx_length 15unsigned char iic_tx_buffer[]={0x03,0x00,0x04}; //read temperature and Humidity command (no CRC check) unsigned  char iic_rx_buffer[iic_rx_length] = {0x00};//read back temperature and humidity Unsigned char uart_rx_buffer [30] = {0x00};unsigned char *string;unsigned char wr_flag;//string Definition #define s_ function   "Function: 03 04 "#define  S_Temp  Temp:" #define  S_RH    "RH:" #define  s _crct  "Crc: true" #define  S_CRCF  "Crc: wrong" #define  S_Data  "data: " # define s_nots  "sensor not connected" void ack (void); Void noack (void);  void  delay10us (void)  //This delay function   to be greater than 5US {  _nop_ ();  _nop_ ();  _nop_ ();    _nop_ ();  _nop_ ();  _nop_ ();  } void delay1ms (unsigned int t) {   unsigned int i;  unsigned int j;  for (j=t;j>0;j--)     for (i=124;i>0;i--);   }void inituart (void) {unsigned int itmpbaud; unsigned long ltmpbaud;itmpbaud = 0;//First select Timer 2 as the baud rate generator, 16-bit timer, automatic loading scon = 0x50;// Sm0 sm1 sm2 ren tb8 rb8 ti ri//0   1   0    1  &nbSp;0   0   0  0pcon = 0x00;//pcon's address is 87H, here Smod =0t2con  = 0x30;//tf2 exf2 rclk tclk exen2 tr2 c (/T2)  CP (/RL2)  //0  0 1 1 0 0 0 0 T2MOD = 0x00;// //////T2OEDCEN    //0 0 0 0 0 0 0 0//fosc = 22.1184m,6t: 144, setting the baud rate (rcap2h,rcap2l)  = 65536- fosc/(N*baud). N:32 (12t-mode),: (6t-mode) ltmpbaud = fosc/baud;ltmpbaud /= 32;//12t-modeitmpbaud =  lTmpBaud & 0xFFFF;iTmpBaud = 65536 - iTmpBaud; rcap2h =  (itmpbaud>>8)  & 0x0FF; rcap2l = itmpbaud & 0x0ff; ri = 0;//clear receive interrupt flag ren = 1;//allow serial receive es = 1;//allow serial interrupt tr2 = 1;//start timer 1     ea=1;//Open Total interrupt}  //serial port send Void uartsend (Char uchar) {    sbuf=uchar;  while (ti==0);   ti=0;} Void uartread (void)  interrupt 4{  char temp;  if (RI)   {     ri=0;    temp = sbuf;  }}//******************* Send starting Bit  sda=1->0void i2c_start () {  sda=1;  scl=1;   delay10us ();   sda=0;  delay10us ();   scl=0; }//***************** Send Stop Bit  sda=0->1void i2c_stop () {   sda=0;    delay10us ();    scl=1;   delay10us ();    sda=1;} Main answer (contains ack:sda=0 and no_ack:sda=0) void ack (void) {   //set sda  port as output    sda=0;   scl=0;   delay10us ();  &NBSP;&NBSP;SCL=1;&NBSP;&NBSP;&NBSP;DELAY10US ();   scl=0;   sda=1;} Void noack (void) {  //set sda  port as output    sda=1;     scl=0 ;    delay10us ();    scl=1;   delay10us ();   SDA=1;    scl=0;}   detects if &NBSP;SDA back Ackbit test_ack () {  //set sda  port as input    bit ack_flag= 0;&NBSP;&NBSP;&NBSP;SCL=0;&NBSP;&NBSP;&NBSP;SDA=1;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;DELAY10US ();    scl=1;   delay10us ();    if (sda==0)      ack_ flag = 1;   else      ack_flag = 0;    scl=0;   return ack_flag;} BYTE sender//Send C (can be data also address), sent after receiving from answer//not considered from the answer bit void  SendData (unsigned char buffer) {   unsigned char bitcnt=8;//byte 8 bits     //set sda  port as output     do   {   scl=0;  delay10us ();       if ((buffer&0x80) ==0)  //determine whether the highest bit is 0 or 1        sda=0;       else        SDA=1;       scl=1;  delay10us ();       buffer=buffer<<1;// Move data in buffer to the left one       bitcnt--;   }   while (BitCnt) ;    scl=0;        }//********************************** BYTE receiver//receiving device data transmitted, this program should match | The main answer function |i2c_ack_main () using the//return: uchar type 1 byte unsigned char  receivedata () {  unsigned char bitcnt=8,iic_rx_data=0;  unsigned char  temp=0;  sda=1;           //read-in data   Set sda  port as input   d o  {     scl=0; delay10us ();    iic_rx_data=_crol_ (IIC _rx_data,1)    //data shift left one &NBSP;BITCNT--;&NBSP;&NBSP;&NBSP;SCL=1;&NBSP;DELAY10US ();      if (sda==1)        iic_rx_data = iic_rx_data|0x01 ;   //Low Position 1     else       iic_rx_data  = iic_rx_data&0x0fe; //Low 0       }    while (bitcnt);    scl=0;   return iic_rx_data;} Bit writenbyte (unsigned char sla,unsigned  char *s,unsigned char n) {   unsigned char i;       i2c_start ();   //start I2c   senddata (SLA);//Send Device Address    if ( ! Test_ack ()) &NBSP;&NBSP;&NBSP;{&NBSP;&NBSP;&NBSP;&NBsp;  wr_flag = 1;  return (0);    }   for (i=0;i< n;i++)//write 8 bytes of data    {      senddata (* (s+i));   if (! Test_ack ())   {    wr_flag = 1;return (0);  }    }   i2c_stop ();    return (1);} Bit readnbyte (unsigned char sal, unsigned char *p,unsigned char n) {   unsigned char i;  i2c_start ();    //  start i2c   senddata (Sal) | 0x01);  //Send device address   if (! Test_ack ())   {  wr_flag = 1;return (0);   }  delay10us ();     delay10us ();   delay10us (); //  delay time must be greater than 30us  as long as it is greater than  30us   Above the value can be   but preferably not too long  , test, tried 25MS are ok!            for (i=0;i<n-1;i++)   //read byte data   {     * (P+i) =receivedata ();  //Read Data       ack ();    }  * (p+n-1) =receivedata ();           noack ();   i2c_stop ();    return (1);  }/// Calculate CRC Check Code UNSIGNED&NBSP;INT&NBSP;CRC16 (Unsigned char *ptr, unsigned char len) {    unsigned int crc=0xffff;   unsigned char i;    while (len--)    {       crc ^=*ptr++;        for (i=0;i<8;i++)    {       if (CRC  & 0x1)    {      crc>>=1;  crc^= 0xa001;   }   else   {      crc> >=1;   }&nbsP;&NBSP;&NBSP;}&NBSP;&NBSP;&NBSP;}&NBSP;&NBSP;&NBSP;RETURN&NBSP;CRC;} Check that the CRC check code is correct UNSIGNED&NBSP;CHAR&NBSP;CHECKCRC (Unsigned char *ptr,unsigned char len) {   unsigned int crc;crc= (Unsigned int) CRC16 (ptr,len-2); if (ptr[len-1]== (crc>>8)  && ptr[len-2]== (CRC&NBSP;&AMP;&NBSP;0X00FF)) {    return 0xff;} else{   return 0x0;}} Void waken (void)    {    i2c_start ();        //  start I2c    senddata (iic_add); //  send device Address      test_ack ();       //  wake-up instruction   sensor does not return to ack  but the first must send a clock to detect Ack   otherwise error     delay1ms (2);       //  at least 1 ms instructions, There is a maximum value of   In practice   you only need to be greater than 1ms    i2c_stop ();    }void uart_putstring ( Unsigned char *buf&nbsP;) {while (*BUF)       uartsend (*buf++);}  void uart_putstringandnum (unsigned char *buf ,unsigned int num) {unsigned  char a[3],i;a[3] =  ' 0 ' +num%10;a[2] =  '; a[1] =  ' 0 ' +num/10%10;a[0] =  ' 0 ' +num/100%10;while (*buf)        Uartsend (*buf++); Uartsend ('   ');  for (i=0;i<4;i++) {uartsend (a[i]);}  }void uart_putstringand_data (Unsigned char *buf ,unsigned char *bufdata)   {unsigned char a[2],i,j;while (*BUF)       uartsend (*buf++); Uartsend ('   '); for (i=0;i<8;i++) {a[0] = bufdata[i]/16; a[1] = bufdata[i]%16;for (j=0;j<2;j++) {  if (a[j]>9)   {    a[j] =  (a[j]-10) + ' a ';   }   else  {    a[j] = a[j]+ ' 0 ';  }   Uartsend(A[j]);} Uartsend ('   ');}    }void uartsend_nbyte (void)       {   int  tmp;    if (wr_flag == 0)    { if (CheckCRC (IIC_RX_Buffer , 8))  {   String = S_Function;  //  "function: 03 04"        uart_putstring (String);         uartsend ('   ');        uartsend ('   ');        string = s_rh;//"RH:"            tmp = iic_rx_buffer[2]*256+iic_rx_buffer[3];           uart_putstringandnum (string,tmp);            Uartsend ('   ');        uartsend ('   ');       string = s_temp; //"Temp:"                  Tmp = IIC_RX_Buffer[4]*256+IIC_RX_Buffer[5];           uart_putstringandnum (string,tmp);       uartsend ('   ');        uartsend ('   ');    string = s_crct;//"Crc: true";    uart_putstring (String);  }else {string  = s_data;//"data: "; Uart_putstringand_data (String,iic_rx_buffer);   uartsend ('   ');   uartsend ('   '); string = s_crcf;//"Crc: wrong";       uart_putstring (String);   }    }else{   string = s_nots;//"Sensor Not  connected ";     uart_putstring (String);}        Uartsend (0x0A);           }  void clear_data   (void)      {    int i;    for (i=0; i<iic_rx_length;i++)      {     iic_rx_buffer[i] =  0x00;     }//receive data clear 0   }void main (void) {  scl =  1;  sda = 1; //Power on the two bus to ensure that the high   inituart ();   clear_data ();   while (1)   {clear_data (); //  Clear received data wr_flag = 0; Waken ();  //  wake-up sensor     //send Read command     writenbyte (IIC_Add,IIC _tx_buffer,3)      //at least 2MS after sending the read or write Data command (to prepare the probe for time to return data) delay1ms (2);     //read return Data     readnbyte (iic_add,iic_rx_buffer,8); scl = 1; sda = 1;//confirm the release bus   //send sensor data up through the serial port Uartsend_Nbyte ();     delay1ms (two),   //time delay  2s (at least 2S)   }} 

Compiling diagram:

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AM2320 temperature and humidity sensor C51 program UART serial output temperature and humidity