//----------------------------------------------------------------------------------
char sht_read_statusreg(void)
//----------------------------------------------------------------------------------
// reads the status register with checksum (8-bit)
{
unsigned char error=0;
unsigned char tmp = 0;
unsigned char bits = 8;
sht_crc_init();
sht_transstart(); //transmission start
error=sht_write_byte(STATUS_REG_R); //send command to sensor
sht_crc_shuffle_byte(STATUS_REG_R);
StatusReg =sht_read_byte(ACK); //read status register (8-bit)
sht_crc_shuffle_byte(StatusReg);
CheckSum =sht_read_byte(noACK); //read checksum (8-bit)
while( bits--)
{
tmp >>=1;
if( sht_crc & 0b10000000)
tmp |= 0b10000000;
sht_crc <<=1;
}
if (tmp != CheckSum) {
SHTdevice_table[CurrentSensorIndex].crc++;
error++;
}
return error; //error=1 in case of no response form the sensor
}
//----------------------------------------------------------------------------------
unsigned char sht_measure(sht_value *p_sht_value, unsigned char *p_checksum, unsigned char mode, unsigned char pin)
//----------------------------------------------------------------------------------
// makes a measurement (humidity/temperature) with checksum
{
unsigned char error=0;
unsigned char i;
sht_value this_sht_value;
/* sht_transstart(pin); //transmission start */
sht_connectionreset(pin);
switch(mode)
{ //send command to sensor
case TEMP : error+=sht_write_byte(MEASURE_TEMP, pin); /*usart_write("TEMP: ");*/ break;
case HUMI : error+=sht_write_byte(MEASURE_HUMI, pin); /*usart_write("HUMI: ");*/ break;
default : break;
}
for (i=0;i<500;i++) {
if(SHT_DATA(pin)==0) break; //wait until sensor has finished the measurement
_delay_ms(1); // neccesary since the AVR is so much faster than the old 8051
// and the 210ms for 14bit measuremnt are only a rough estimate
}
if(SHT_DATA(pin)) error+=1; // or timeout is reached
this_sht_value.i = 256*sht_read_byte(ACK, pin); //read the first byte (MSB)
this_sht_value.i +=sht_read_byte(ACK, pin); //read the second byte (LSB)
*p_checksum =sht_read_byte(noACK, pin); //read checksum
*(p_sht_value)= this_sht_value;
return error;
}
//----------------------------------------------------------------------------------
// reads the status register with checksum (8-bit)
//----------------------------------------------------------------------------------
char sht_read_statusreg(unsigned char *p_value, unsigned char *p_checksum)
{
unsigned char error=0;
sht_transstart(); //transmission start
error=sht_write_byte(STATUS_REG_R); //send command to sensor
*p_value=sht_read_byte(ACK); //read status register (8-bit)
*p_checksum=sht_read_byte(noACK); //read checksum (8-bit)
return error; //error=1 in case of no response form the sensor
}
//----------------------------------------------------------------------------------
char sht_measure(unsigned char mode)
//----------------------------------------------------------------------------------
// makes a measurement (humidity/temperature) with checksum
{
unsigned error=0;
unsigned int i;
unsigned char LSB;
unsigned char MSB;
unsigned char tmp = 0;
unsigned char bits = 8;
sht_crc_init();
sht_transstart(); //transmission start
switch(mode){ //send command to sensor
case TEMP : error+=sht_write_byte(MEASURE_TEMP); sht_crc_shuffle_byte(MEASURE_TEMP);break;
case HUMI : error+=sht_write_byte(MEASURE_HUMI); sht_crc_shuffle_byte(MEASURE_HUMI);break;
default : break;
}
for (i=0;i<40000;i++) {
if(DATA_IN==0) {
break; //wait until sensor has finished the measurement
}
Delay100TCYx(4); //50 us
}
if(DATA_IN)
{
error+=1; // or timeout (~2 sec.) is reached
}
MSB = sht_read_byte(ACK); //read the first byte (MSB)
sht_crc_shuffle_byte(MSB);
LSB = sht_read_byte(ACK); //read the second byte (LSB)
sht_crc_shuffle_byte(LSB);
CurrentValue = MSB * 256 + LSB;
CheckSum = sht_read_byte(noACK); //read checksum
while( bits--)
{
tmp >>=1;
if( sht_crc & 0b10000000)
tmp |= 0b10000000;
sht_crc <<=1;
}
if (tmp != CheckSum) {
SHTdevice_table[CurrentSensorIndex].crc++;
return 1;
}
return error;
}
char sht_measure( unsigned char *p_value, unsigned char *p_checksum, unsigned char mode )
{
unsigned error=0;
unsigned long i;
sht_transstart(); // transmission start
switch( mode ) { // send command to sensor
case SHT_MODE_TEMP:
error += sht_write_byte( MEASURE_TEMP );
break;
case SHT_MODE_HUMI:
error += sht_write_byte( MEASURE_HUMI );
break;
default:
break;
}
// wait until sensor has finished the measurement
sht_measure_timer = 0;
while ( sht_measure_timer < SHT_READ_TIMEOUT ) {
if ( 0 == ( PORTCbits.RC5 ) ) {
break;
}
}
if ( PORTCbits.RC5 ) { // or timeout (~2 sec.) is reached
error += 1;
}
*(p_value) = sht_read_byte( ACK ); // read the first byte (MSB)
*(p_value+1)= sht_read_byte( ACK ); // read the second byte (LSB)
*p_checksum = sht_read_byte( noACK ); // read checksum
return error;
}
//----------------------------------------------------------------------------------
// read measurement
//----------------------------------------------------------------------------------
void sht_measure_read(unsigned char *p_value, unsigned char *p_checksum)
{
*(p_value+1) = sht_read_byte(ACK); // read the first byte (MSB)
*(p_value) = sht_read_byte(ACK); // read the second byte (LSB)
*p_checksum = sht_read_byte(noACK); // read checksum
}
