DHT22 temperature and humidity sensor

Files
file	dht22.c
	Driver for the DHT22 temperature and humidity sensor.
file	dht22.h
	Header file for the DHT22 temperature and humidity sensor.

Functions
static int	dht22_read (void)

DHT22 constants
#define	DHT22_BUFFER   5
	Buffer to store the samples
#define	DHT22_COUNT   8
	Minimum ticks to detect a "1" bit
#define	DHT22_MAX_TIMMING   85
	Maximum ticks in a single operation.
#define	DHT22_READING_DELAY   1
	1 us
#define	DHT22_READY_TIME   40
	40 us
#define	DHT22_START_TIME   (RTIMER_SECOND / 50)
	20 ms
#define	DHT22_AWAKE_TIME   (RTIMER_SECOND / 4)
	250 ms

Detailed Description

Driver for the DHT22 temperature and humidity sensor

Function Documentation

dht22_read()

static int dht22_read ( void )

static

< 250 ms

< Buffer to store the samples

< 20 ms

< 40 us

< Maximum ticks in a single operation

< 1 us

< Minimum ticks to detect a "1" bit

< Buffer to store the samples

Definition at line 62 of file dht22.c.

References clock_delay_usec(), DHT22_AWAKE_TIME, DHT22_BUFFER, DHT22_COUNT, DHT22_MAX_TIMMING, DHT22_READING_DELAY, DHT22_READY_TIME, DHT22_START_TIME, GPIO_CLR_PIN, GPIO_READ_PIN, GPIO_SET_INPUT, GPIO_SET_OUTPUT, GPIO_SET_PIN, and RTIMER_BUSYWAIT.