firmware.c

SHT11温度湿度传感器的详细资料包获C代码和使用方法

#include <avr/io.h>

#define CLOCK 4000000
#define BAUD 9600
#define UBRRVAL CLOCK/(BAUD*16L)-1

#define noACK 0
#define ACK 1

#define STATUS_REG_W  0x06
#define STATUS_REG_R  0x07
#define MEASURE_TEMP  0x03
#define MEASURE_HUMI  0x05
#define RESET         0x1e

#define setREAD       outb(DDRB, 0x01); sbi(PORTB, 1)
#define setWRITE      outb(DDRB, 0x03)
#define SCK(i)        if (i) sbi(PORTB, 0); else cbi(PORTB, 0)
#define DATA(i)       if (i) sbi(PORTB, 1); else cbi(PORTB, 1)

enum {TEMP, HUMI};

void UART_Init() {
  outb(UBRR, UBRRVAL);  // Baudrate einstellen
  sbi(UCR,TXEN);        // TX aktivieren
}

void UART_SendChar(char s) {
  loop_until_bit_is_set(USR, UDRE);
  outb (UDR, s);
}

void UART_SendStr(char *s) {
  while (*s) {
    loop_until_bit_is_set(USR, UDRE);
    outb (UDR, *s++);
  }
}

void delay_us(unsigned int us) {
  while (us) us--;
}

void delay_ms(unsigned int ms) {
  unsigned int outer1, outer2;
  outer1 = 200; 
  while (outer1) {
    outer2 = 1000;
    while (outer2) {
      while ( ms ) ms--;
      outer2--;
    }
    outer1--;
  }
}

void transStart() {
  DATA(1);  SCK(0);
  delay_us(1);
  SCK(1);
  delay_us(1);
  DATA(0);
  delay_us(1);
  SCK(0);
  delay_us(5);
  SCK(1);
  delay_us(1);
  DATA(1);
  delay_us(1);
  SCK(0);
}

void connReset() {
  unsigned int i;
  setWRITE;
  DATA(1); SCK(0);
  for(i=0; i<9; i++) {
    SCK(1);
    SCK(0);
  }
  transStart();
}

unsigned int getDATA() {
  return bit_is_set(PINB, 1);
}

unsigned char writeByte(unsigned char value) {
  unsigned char i, error=0;
  setWRITE;
  for(i=0x80;i>0;i/=2) {
    if (i & value) DATA(1);
    else DATA(0);
    SCK(1);
    delay_us(5);
    SCK(0);
  }
  setREAD; 
  SCK(1);
  delay_us(1);
  error=getDATA();
  SCK(0);
  return error;
}

unsigned char readByte(unsigned char ack) {
  unsigned char i,val=0;
  setREAD;
  for(i=0x80;i>0;i/=2) {
    SCK(1);
    if (getDATA()) val=(val | i);
    SCK(0);
  }
  setWRITE;
  DATA(!ack);
  SCK(1);
  delay_us(5);
  SCK(0);
  return val;
}

void conv_byte(unsigned char in, unsigned char *out)
{
  unsigned char a;
  a=in&0xf0;
  a=a>>4;
  if(a>9) {
    out[0]=a-10+0x41;
  } else {
    out[0]=a+0x30;
  }
  a=in&0x0f;
  if(a>9) {
    out[1]=a-10+0x41;
  } else {
    out[1]=a+0x30;
  }
}

void conv_int(int in, unsigned char * out) {
  unsigned int temp;
  unsigned char a;
  if(in>=0) {
    temp=in&0xff00;
    a=(unsigned char)(temp>>8);
    conv_byte(a,out);
    a=(in&0x00ff);
    conv_byte(a,out+2);
  } else {
    *out='-';
    out++;
    in*=-1;
    temp=in&0xff00;
    a=(unsigned char)(temp>>8);
    conv_byte(a,out);
    a=(in&0x00ff);
    conv_byte(a,out+2);
  }
}

unsigned char measure(unsigned int *p_value, unsigned char *p_checksum, unsigned char mode) {
  unsigned char lsb,msb,check;
  unsigned char error=0;
  unsigned int i;

  transStart();
  switch(mode) {
    case TEMP : error+=writeByte(MEASURE_TEMP); break;
    case HUMI : error+=writeByte(MEASURE_HUMI); break;
    default   : break;
  }
  setREAD;
  for(i=0;i<65535;i++) if (getDATA()==0) break;
  if (getDATA()) error+=1;
  *p_value = readByte(ACK);
  *p_value<<=8;
  *p_value+= readByte(ACK);
  *p_checksum = readByte(noACK);
  return error;
}  

int main() {
  unsigned char check,error;
  unsigned char c[5];
  unsigned int i,temp,humi;
  
  UART_Init();
  connReset();
  
  while(1) {

    error=0;
    error+=measure(&temp, &check, TEMP);
    error+=measure(&humi, &check, HUMI);
    
    if (error) connReset();
    else {
      
      for(i=0;i<5;i++) c[i]='\0';
      conv_int(temp, c);
      UART_SendStr(c);

      UART_SendStr(" ");
      
      for(i=0;i<5;i++) c[i]='\0';
      conv_int(humi, c);
      UART_SendStr(c);

      UART_SendStr("\n");
    }

    delay_ms(10000);
  }
}