The DHT11/DHT22’s DATA pin detects an external signal and goes low, indicating that it is waiting for the external signal to complete. Once the signal ends, the DHT11/DHT22’s DATA pin switches to output mode, producing a low signal for 80 microseconds as a response. This is followed by an 80-microsecond high signal, notifying the microprocessor that the sensor is ready to transmit data. At this point, the microprocessor's I/O pin, still in input mode, detects the low signal from the DHT11/DHT22 (indicating the response) and then waits for the 80-microsecond high signal to start receiving data. The sequence of signal transmission is illustrated below:
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