nes-proj/platform/zoul/dev/dht22.c
2016-07-04 18:00:09 +02:00

256 lines
7.8 KiB
C

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