SHT系列C程序样例

void s_connectionreset(void)
//----------------------------------------------------------------------------------
// communication reset: DATA-line=1 and at least 9 SCK cycles followed by transstart
SCK=0;

SHTxx Application Note Sample Code
return error; }
//error=1 in case of no acknowledge
//----------------------------------------------------------------------------------
#define DATA P1_1 #define SCK P1_0
#define noACK 0 #define ACK 1
#define STATUS_REG_W 0x06
#define STATUS_REG_R 0x07
#define MEASURE_TEMP 0x03
#define MEASURE_HUMI 0x05
SCK=0;
}
DATA=!ack;
//in case of "ack==1" pull down DATA-Line
SCK=1;
//clk #9 for ack
_nop_();_nop_();_nop_();
//pulswith approx. 5 us
SCK=0;
DATA=1;
//release DATA-line
DATA=0;
_nop_();
SCK=0;
_nop_();_nop_();_nop_();
SCK=1;
_nop_();
DATA=1;
_nop_();
SCK=0;
}
//----------------------------------------------------------------------------------
{
unsigned char i,val=0;
DATA=1;
//relgt;0;i/=2)
//shift bit for masking
{ SCK=1;
//clk for SENSI-BUS
if (DATA) val=(val | i);
//read bit
#define RESET
0x1e
//adr command r/w //000 0011 0 //000 0011 1 //000 0001 1 //000 0010 1 //000 1111 0
//----------------------------------------------------------------------------------
return val;
}
//----------------------------------------------------------------------------------
void s_transstart(void)
//----------------------------------------------------------------------------------
*p_value=s_read_byte(ACK);
//read status register (8-bit)
*p_checksum=s_read_byte(noACK); //read checksum (8-bit)
return error;
//error=1 in case of no response form the sensor
80C51 family Keil Version 6.14
Autor:
MST
Copyrigth:
(c) Sensirion AG
***********************************************************************************/
#include <AT89s53.h> //Microcontroller specific library, e.g. port definitions #include <intrins.h> //Keil library (is used for _nop()_ operation) #include <math.h> //Keil library #include <stdio.h> //Keil library
SHTxx
Humidity & Temperature Sensmitter
Application Note Sample Code
1 Introduction
This application note gives an example for microcontroller C code. It includes code for: • Readout of Humidity (RH) or Temperature (T) with basic error handling • Calculation of RH linearization and temperature compensation • Access to status register • Dewpoint calculation from RH and T • UART handling
typedef union { unsigned int i;
float f; } value;
//---------------------------------------------------------------------------------// modul-var //---------------------------------------------------------------------------------enum {TEMP,HUMI};
//
_____________________________________________________
________
// DATA:
|_______|
//
_________
___
___
// SCK : __| |__| |__| |__| |__| |__| |__| |__| |__| |______| |___| |______
}
//----------------------------------------------------------------------------------
char s_write_statusreg(unsigned char *p_value)
//----------------------------------------------------------------------------------
// writes the status register with checksum (8-bit)
char s_write_byte(unsigned char value)
//----------------------------------------------------------------------------------
// writes a byte on the Sensibus and checks the acknowledge
unsigned char error=0;

Rev 2.01
2/4
SHTxx Application Note Sample Code
s_transstart();
//transmission start
error=s_write_byte(STATUS_REG_R); //send command to sensor
char s_softreset(void)
//----------------------------------------------------------------------------------
// resets the sensor by a softreset
{
unsigned char error=0;
// generates a transmission start
//
_____
________
// DATA:
|_______|
//
___
___
// SCK : ___| |___| |______
{
DATA=1; SCK=0;
//Initial state
_nop_();
SCK=1;
_nop_();
2 Sample Code
/***********************************************************************************
Project:
SHT11 demo program (V2.0)
Filename:
SHT11.c
Prozessor: Compiler:
s_connectionreset();