Subversion Repositories group.electronics

#include <avr/io.h>

#include <stdlib.h>

#include <avr/pgmspace.h>

#include <util/delay.h>

#include "avrutil.h"

#include "dht.h"

void dht_init(uint8_t port, uint8_t pin, uint8_t type, uint8_t count) {

	dht.port = port;

	dht.pin = pin;

	dht.type = type;

	dht.count = count;

	dht.first = 1;

	dht.data = malloc(6 * sizeof(uint8_t));

}

float dht_readTemp() {

	float t = 0.0;

	if (dht_read()) {

		switch (dht.type) {

			case DHT11:

				t = dht.data[2];

				break;

			case DHT21:

			case DHT22:

				t = dht.data[2] & 0x7F;

				t *= 256;

				t += dht.data[3];

				t /= 10;

				if (dht.data[2] & 0x80)

					t *= -1;

				break;

		}

	}

	return t;

}

uint8_t dht_read() {

	_delay_us(500);

	uint32_t current = systime;

	if (!dht.first && ((current - dht.last) < 2000)) {

		return 1;

	}

	dht.first = 0;

	dht.last = systime;

	return 0;

}