mirror of
https://github.com/oliverschmidt/contiki.git
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256 lines
7.8 KiB
C
256 lines
7.8 KiB
C
/*
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* Copyright (c) 2016, Zolertia - http://www.zolertia.com
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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*/
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/*---------------------------------------------------------------------------*/
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/**
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* \addtogroup zoul-dht22
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* @{
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*
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* \file
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* Driver for the DHT22 temperature and humidity sensor
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*/
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/*---------------------------------------------------------------------------*/
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#include "contiki.h"
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#include "dht22.h"
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#include "dev/gpio.h"
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#include "lib/sensors.h"
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#include "dev/ioc.h"
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#include "dev/watchdog.h"
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#include <stdio.h>
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/*---------------------------------------------------------------------------*/
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#define DEBUG 0
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#if DEBUG
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#define PRINTF(...) printf(__VA_ARGS__)
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#else
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#define PRINTF(...)
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#endif
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/*---------------------------------------------------------------------------*/
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#define BUSYWAIT_UNTIL(max_time) \
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do { \
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rtimer_clock_t t0; \
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t0 = RTIMER_NOW(); \
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while(RTIMER_CLOCK_LT(RTIMER_NOW(), t0 + (max_time))) { \
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watchdog_periodic(); \
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} \
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} while(0)
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/*---------------------------------------------------------------------------*/
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#define DHT22_PORT_BASE GPIO_PORT_TO_BASE(DHT22_PORT)
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#define DHT22_PIN_MASK GPIO_PIN_MASK(DHT22_PIN)
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/*---------------------------------------------------------------------------*/
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static uint8_t enabled;
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static uint8_t busy;
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static uint8_t dht22_data[DHT22_BUFFER];
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/*---------------------------------------------------------------------------*/
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static int
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dht22_read(void)
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{
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uint8_t i;
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uint8_t j = 0;
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uint8_t last_state;
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uint8_t counter = 0;
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uint8_t checksum = 0;
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if(enabled) {
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/* Exit low power mode and initialize variables */
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GPIO_SET_OUTPUT(DHT22_PORT_BASE, DHT22_PIN_MASK);
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GPIO_SET_PIN(DHT22_PORT_BASE, DHT22_PIN_MASK);
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BUSYWAIT_UNTIL(DHT22_AWAKE_TIME);
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memset(dht22_data, 0, DHT22_BUFFER);
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/* Initialization sequence */
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GPIO_CLR_PIN(DHT22_PORT_BASE, DHT22_PIN_MASK);
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BUSYWAIT_UNTIL(DHT22_START_TIME);
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GPIO_SET_PIN(DHT22_PORT_BASE, DHT22_PIN_MASK);
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clock_delay_usec(DHT22_READY_TIME);
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/* Prepare to read, DHT22 should keep line low 80us, then 80us high.
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* The ready-to-send-bit condition is the line kept low for 50us, then if
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* the line is high between 24-25us the bit sent will be "0" (zero), else
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* if the line is high between 70-74us the bit sent will be "1" (one).
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*/
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GPIO_SET_INPUT(DHT22_PORT_BASE, DHT22_PIN_MASK);
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last_state = GPIO_READ_PIN(DHT22_PORT_BASE, DHT22_PIN_MASK);
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for(i = 0; i < DHT22_MAX_TIMMING; i++) {
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counter = 0;
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while(GPIO_READ_PIN(DHT22_PORT_BASE, DHT22_PIN_MASK) == last_state) {
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counter++;
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clock_delay_usec(DHT22_READING_DELAY);
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/* Exit if not responsive */
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if(counter == 0xFF) {
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break;
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}
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}
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last_state = GPIO_READ_PIN(DHT22_PORT_BASE, DHT22_PIN_MASK);
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/* Double check for stray sensor */
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if(counter == 0xFF) {
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break;
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}
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/* Ignore the first 3 transitions (the 80us x 2 start condition plus the
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* first ready-to-send-bit state), and discard ready-to-send-bit counts
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*/
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if((i >= 4) && ((i % 2) == 0)) {
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dht22_data[j / 8] <<= 1;
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if(counter > DHT22_COUNT) {
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dht22_data[j / 8] |= 1;
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}
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j++;
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}
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}
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for(i = 0; i < DHT22_BUFFER; i++) {
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PRINTF("DHT22: (%u) %u\n", i, dht22_data[i]);
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}
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/* If we have 5 bytes (40 bits), wrap-up and end */
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if(j >= 40) {
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/* The first 2 bytes are humidity values, the next 2 are temperature, the
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* final byte is the checksum
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*/
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checksum = dht22_data[0] + dht22_data[1] + dht22_data[2] + dht22_data[3];
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checksum &= 0xFF;
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if(dht22_data[4] == checksum) {
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GPIO_SET_INPUT(DHT22_PORT_BASE, DHT22_PIN_MASK);
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GPIO_SET_PIN(DHT22_PORT_BASE, DHT22_PIN_MASK);
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return DHT22_SUCCESS;
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}
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PRINTF("DHT22: bad checksum\n");
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}
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}
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return DHT22_ERROR;
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}
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/*---------------------------------------------------------------------------*/
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static uint16_t
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dht22_humidity(void)
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{
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uint16_t res;
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res = dht22_data[0];
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res *= 256;
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res += dht22_data[1];
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busy = 0;
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return res;
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}
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/*---------------------------------------------------------------------------*/
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static uint16_t
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dht22_temperature(void)
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{
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uint16_t res;
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res = dht22_data[2] & 0x7F;
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res *= 256;
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res += dht22_data[3];
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busy = 0;
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return res;
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}
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/*---------------------------------------------------------------------------*/
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static int
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value(int type)
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{
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if((type != DHT22_READ_HUM) && (type != DHT22_READ_TEMP) &&
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(type != DHT22_READ_ALL)) {
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PRINTF("DHT22: Invalid type %u\n", type);
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return DHT22_ERROR;
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}
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if(busy) {
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PRINTF("DHT22: ongoing operation, wait\n");
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return DHT22_BUSY;
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}
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busy = 1;
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if(dht22_read() != DHT22_SUCCESS) {
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PRINTF("DHT22: Fail to read sensor\n");
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GPIO_SET_INPUT(DHT22_PORT_BASE, DHT22_PIN_MASK);
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GPIO_SET_PIN(DHT22_PORT_BASE, DHT22_PIN_MASK);
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busy = 0;
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return DHT22_ERROR;
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}
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switch(type) {
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case DHT22_READ_HUM:
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return dht22_humidity();
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case DHT22_READ_TEMP:
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return dht22_temperature();
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case DHT22_READ_ALL:
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return DHT22_SUCCESS;
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default:
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return DHT22_ERROR;
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}
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}
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/*---------------------------------------------------------------------------*/
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int
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dht22_read_all(int *temperature, int *humidity)
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{
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if((temperature == NULL) || (humidity == NULL)) {
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PRINTF("DHT22: Invalid arguments\n");
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return DHT22_ERROR;
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}
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if(value(DHT22_READ_ALL) != DHT22_ERROR) {
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*temperature = dht22_temperature();
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*humidity = dht22_humidity();
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return DHT22_SUCCESS;
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}
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/* Already cleaned-up in the value() function */
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return DHT22_ERROR;
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}
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/*---------------------------------------------------------------------------*/
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static int
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configure(int type, int value)
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{
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if(type != SENSORS_ACTIVE) {
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return DHT22_ERROR;
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}
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GPIO_SOFTWARE_CONTROL(DHT22_PORT_BASE, DHT22_PIN_MASK);
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GPIO_SET_INPUT(DHT22_PORT_BASE, DHT22_PIN_MASK);
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ioc_set_over(DHT22_PORT, DHT22_PIN, IOC_OVERRIDE_OE);
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GPIO_SET_PIN(DHT22_PORT_BASE, DHT22_PIN_MASK);
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/* Restart flag */
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busy = 0;
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if(value) {
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enabled = 1;
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return DHT22_SUCCESS;
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}
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enabled = 0;
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return DHT22_SUCCESS;
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}
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/*---------------------------------------------------------------------------*/
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SENSORS_SENSOR(dht22, DHT22_SENSOR, value, configure, NULL);
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/*---------------------------------------------------------------------------*/
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/** @} */
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