m’kay, so im using the grove temp/hum sensor on a seeeduino film board. I have the signal connected to Ao vcc to vcc, gnd to gnd, nc not connected, etc, etc. anyhow, I’m using the exact code on the wiki, and as a look at my console all is see is “dht11 start condition 2 not met” over and over and over… is this because the data shield is necessary? is going directly to the seeeduino film the wrong thing to do? here is the wiki code for reference. maybe if someone could explain to me the lines of code where it generates this message…
#define DHT11_PIN 0 // ADC0
byte read_dht11_dat()
{
byte i = 0;
byte result=0;
for(i=0; i< 8; i++){
while(!(PINC & _BV(DHT11_PIN))); // wait for 50us
delayMicroseconds(30);
if(PINC & _BV(DHT11_PIN))
result |=(1<<(7-i));
while((PINC & _BV(DHT11_PIN))); // wait '1' finish
}
return result;
}
void setup()
{
DDRC |= _BV(DHT11_PIN);
PORTC |= _BV(DHT11_PIN);
Serial.begin(9600);
Serial.println("Ready");
}
void loop()
{
byte dht11_dat[5];
byte dht11_in;
byte i;
// start condition
// 1. pull-down i/o pin from 18ms
PORTC &= ~_BV(DHT11_PIN);
delay(18);
PORTC |= _BV(DHT11_PIN);
delayMicroseconds(40);
DDRC &= ~_BV(DHT11_PIN);
delayMicroseconds(40);
dht11_in = PINC & _BV(DHT11_PIN);
if(dht11_in){
Serial.println("dht11 start condition 1 not met");
return;
}
delayMicroseconds(80);
dht11_in = PINC & _BV(DHT11_PIN); //what the heck does this do?????
if(!dht11_in){
Serial.println("dht11 start condition 2 not met");
return;
}
delayMicroseconds(80);
// now ready for data reception
for (i=0; i<5; i++)
dht11_dat[i] = read_dht11_dat();
DDRC |= _BV(DHT11_PIN);
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)
{
Serial.println("DHT11 checksum error");
}
Serial.print("Current humdity = ");
Serial.print(dht11_dat[0], DEC);
Serial.print(".");
Serial.print(dht11_dat[1], DEC);
Serial.print("% ");
Serial.print("temperature = ");
Serial.print(dht11_dat[2], DEC);
Serial.print(".");
Serial.print(dht11_dat[3], DEC);
Serial.println("C ");
delay(2000);
}