byte read_dht11_dat() {
byte j = 0;
byte result = 0;
for (j = 0; j < 8; j++) {
while (!DHT_GetVal());//while (!(PINC & _BV(DHT11_PIN))); // wait for 50us
WAIT1_Waitus(30);//delayMicroseconds(30);
if (DHT_GetVal())//if (PINC & _BV(DHT11_PIN))
{
result |= (1 << (7 - j));
while (DHT_GetVal());//while ((PINC & _BV(DHT11_PIN))); // wait '1' finish
}
}
return result;
}
void DHT11() {
byte dht11_in;
byte i;
// output
DHT_SetDir(1);
// pull-down i/o pin for 18ms
DHT_ClrVal();
WAIT1_Waitms(19);
DHT_SetVal();
//pull-up i/o pin for 30ms
WAIT1_Waitus(30);
//input
DHT_SetDir(0);
WAIT1_Waitus(30);
while(!dht11_in)
{
dht11_in = DHT_GetVal();//dht11_in = PINC & _BV(DHT11_PIN);
}
// if (dht11_in) {
// printf("dht11 start condition 1 not met\r\n");
// return;
// }
WAIT1_Waitus(80);//delayMicroseconds(80);
// dht11_in = DHT_GetVal();//dht11_in = PINC & _BV(DHT11_PIN);
// if (!dht11_in) {
// printf("dht11 start condition 2 not met\r\n");
// return;
// }
// WAIT1_Waitus(80);//delayMicroseconds(80);
// now ready for data reception
for (i = 0; i < 5; i++)
dht11_dat[i] = read_dht11_dat();
DHT_SetDir(1);//DDRC |= _BV(DHT11_PIN);
DHT_SetVal();//PORTC |= _BV(DHT11_PIN);
byte dht11_check_sum = dht11_dat[0] + dht11_dat[1] + dht11_dat[2]
+ dht11_dat[3];
// check check_sum
if (dht11_dat[4] != dht11_check_sum) {
printf("DHT11 checksum error\r\n");
}
printf("Current humdity = ");
printf("%d",dht11_dat[0]);
printf(".");
printf("%d",dht11_dat[1]);
printf("%%\r\n");
printf("temperature = ");
printf("%d",dht11_dat[2]);
printf(".");
printf("%d",dht11_dat[3]);
printf("C \r\n");
// WAIT1_Waitms(2000);//delay(2000);
}
int Read(uint8_t *temp, uint8_t *humi) {
int cntr;
int loopBits;
uint8_t buffer[5];
int i;
int data;
/* init buffer */
for (i = 0; i < sizeof(buffer); i++) {
buffer[i] = 0;
}
//set to input and check if the signal gets pulled up
DHT_SetInput();
WAIT1_Waitus(50);
if (DHT_GetVal() == 0) {
return NO_PULLUP;
}
// send start signal
DHT_SetOutput();
DHT_ClrVal();
WAIT1_Waitms(18); /* keep signal low for at least 18 ms */
DHT_SetInput();
WAIT1_Waitus(50);
/* check for acknowledge signal */
if (DHT_GetVal() != 0) { /* signal must be pulled low by the sensor */
return NO_ACK_0;
}
/* wait max 90 us for the ack signal from the sensor */
cntr = 18;
while (DHT_GetVal() == 0) { /* wait until signal goes up */
WAIT1_Waitus(5);
if (--cntr == 0) {
return NO_ACK_1; /* signal should be up for the ACK here */
}
}
/* wait until it goes down again, end of ack sequence */
cntr = 18;
while (DHT_GetVal() != 0) { /* wait until signal goes down */
WAIT1_Waitus(5);
if (--cntr == 0) {
return NO_ACK_0; /* signal should be down to zero again here */
}
}
/* now read the 40 bit data */
i = 0;
data = 0;
loopBits = 40;
do {
cntr = 11; /* wait max 55 us */
while (DHT_GetVal() == 0) {
WAIT1_Waitus(5);
if (--cntr == 0) {
return NO_DATA_0;
}
}
cntr = 5; /* wait max 75 us */
while (DHT_GetVal() != 0) {
WAIT1_Waitus(15);
if (--cntr == 0) {
return NO_DATA_1;
}
}
data <<= 1; /* next data bit */
if (cntr < 3) { /* data signal high > 40 us ==> data bit 1 */
data |= 1;
}
if ((loopBits & 0x7) == 1) { /* next byte */
buffer[i] = data;
i++;
data = 0;
}
} while (--loopBits != 0);
/* now we have the 40 bit (5 bytes) data:
* byte 1: humidity integer data
* byte 2: humidity decimal data (not used for DTH11, always zero)
* byte 3: temperature integer data
* byte 4: temperature fractional data (not used for DTH11, always zero)
* byte 5: checksum, the sum of byte 1 + 2 + 3 + 4
*/
/* test CRC */
if (buffer[0] + buffer[1] + buffer[2] + buffer[3] != buffer[4]) {
return BAD_CRC;
}
/* store data values for caller */
*humi = ((int) buffer[0]);
*temp = ((int) buffer[2]);
return OK;
}
