258 lines
6.7 KiB
C
258 lines
6.7 KiB
C
//
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// FILE: dht.cpp
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// AUTHOR: Rob Tillaart
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// VERSION: 0.1.14
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// PURPOSE: DHT Temperature & Humidity Sensor library for Arduino
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// URL: http://arduino.cc/playground/Main/DHTLib
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//
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// HISTORY:
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// 0.1.14 replace digital read with faster (~3x) code => more robust low MHz machines.
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// 0.1.13 fix negative dht_temperature
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// 0.1.12 support DHT33 and DHT44 initial version
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// 0.1.11 renamed DHTLIB_TIMEOUT
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// 0.1.10 optimized faster WAKEUP + TIMEOUT
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// 0.1.09 optimize size: timeout check + use of mask
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// 0.1.08 added formula for timeout based upon clockspeed
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// 0.1.07 added support for DHT21
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// 0.1.06 minimize footprint (2012-12-27)
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// 0.1.05 fixed negative dht_temperature bug (thanks to Roseman)
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// 0.1.04 improved readability of code using DHTLIB_OK in code
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// 0.1.03 added error values for temp and dht_humidity when read failed
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// 0.1.02 added error codes
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// 0.1.01 added support for Arduino 1.0, fixed typos (31/12/2011)
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// 0.1.00 by Rob Tillaart (01/04/2011)
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//
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// inspired by DHT11 library
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//
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// Released to the public domain
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//
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// #define NODE_DEBUG
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#include "user_interface.h"
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#include "platform.h"
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#include <stdio.h>
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#include "dht.h"
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#ifndef LOW
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#define LOW 0
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#endif /* ifndef LOW */
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#ifndef HIGH
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#define HIGH 1
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#endif /* ifndef HIGH */
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#define COMBINE_HIGH_AND_LOW_BYTE(byte_high, byte_low) ((uint16_t)((byte_high) << 8) | (byte_low))
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static double dht_humidity;
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static double dht_temperature;
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static uint8_t dht_bytes[5]; // buffer to receive data
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static int dht_readSensor(uint8_t pin, uint8_t wakeupDelay);
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/////////////////////////////////////////////////////
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//
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// PUBLIC
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//
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// return values:
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// Humidity
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double dht_getHumidity(void)
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{
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return dht_humidity;
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}
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// return values:
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// Temperature
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double dht_getTemperature(void)
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{
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return dht_temperature;
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}
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// return values:
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// DHTLIB_OK
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// DHTLIB_ERROR_CHECKSUM
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// DHTLIB_ERROR_TIMEOUT
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int dht_read(uint8_t pin, dht_type type)
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{
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// READ VALUES
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int rv = dht_readSensor(pin,
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type == DHT22 ? DHTLIB_DHT_WAKEUP :
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type == DHT11 ? DHTLIB_DHT11_WAKEUP :
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DHTLIB_DHT_UNI_WAKEUP
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);
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if (rv != DHTLIB_OK)
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{
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dht_humidity = DHTLIB_INVALID_VALUE; // invalid value, or is NaN prefered?
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dht_temperature = DHTLIB_INVALID_VALUE; // invalid value
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return rv; // propagate error value
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}
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NODE_DBG("DHT registers: %x\t%x\t%x\t%x\t%x == %x\n", dht_bytes[0], dht_bytes[1], dht_bytes[2], dht_bytes[3], dht_bytes[4], (uint8_t)(dht_bytes[0] + dht_bytes[1] + dht_bytes[2] + dht_bytes[3]));
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// Assume it is special case of DHT11,
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// i.e. positive temperature and dht_bytes[3] == 0 ((dht_bytes[3] & 0x0f) * 0.1 to be added to temperature readout)
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// If it is DHT11, both temp and humidity's decimal
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dht_humidity = dht_bytes[0];
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dht_temperature = dht_bytes[2];
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if ((dht_bytes[1] == 0) && (dht_bytes[3] == 0))
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{
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// It may DHT11
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// CONVERT AND STORE
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NODE_DBG("DHT11 method\n");
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// TEST CHECKSUM
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uint8_t sum = dht_bytes[0] + dht_bytes[2];
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if (dht_bytes[4] == sum)
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{
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return DHTLIB_OK;
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}
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}
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// Assume it is not DHT11 special case
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// CONVERT AND STORE
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NODE_DBG("DHTxx method\n");
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switch (type) {
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case DHT11:
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case DHT12:
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dht_humidity += dht_bytes[1] * 0.1;
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break;
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default:
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dht_humidity = COMBINE_HIGH_AND_LOW_BYTE(dht_bytes[0], dht_bytes[1]) * 0.1;
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break;
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}
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switch (type) {
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case DHT11:
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if (dht_bytes[3] & 0x80) {
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dht_temperature = -1 - dht_temperature;
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}
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dht_temperature += (dht_bytes[3] & 0x0f) * 0.1;
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break;
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case DHT12:
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dht_temperature += (dht_bytes[3] & 0x0f) * 0.1;
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if (dht_bytes[2] & 0x80) // negative dht_temperature
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{
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dht_temperature *= -1;
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}
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break;
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default: // DHT22, DHT_NON11
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dht_temperature = COMBINE_HIGH_AND_LOW_BYTE(dht_bytes[2] & 0x7F, dht_bytes[3]) * 0.1;
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if (dht_bytes[2] & 0x80) // negative dht_temperature
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{
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dht_temperature *= -1;
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}
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break;
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}
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// TEST CHECKSUM
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uint8_t sum = dht_bytes[0] + dht_bytes[1] + dht_bytes[2] + dht_bytes[3];
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if (dht_bytes[4] != sum)
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{
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return DHTLIB_ERROR_CHECKSUM;
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}
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return DHTLIB_OK;
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}
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/////////////////////////////////////////////////////
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//
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// PRIVATE
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//
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// return values:
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// DHTLIB_OK
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// DHTLIB_ERROR_TIMEOUT
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int dht_readSensor(uint8_t pin, uint8_t wakeupDelay)
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{
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// INIT BUFFERVAR TO RECEIVE DATA
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uint8_t mask = 128;
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uint8_t idx = 0;
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uint8_t i = 0;
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// replace digitalRead() with Direct Port Reads.
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// reduces footprint ~100 bytes => portability issue?
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// direct port read is about 3x faster
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// uint8_t bit = digitalPinToBitMask(pin);
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// uint8_t port = digitalPinToPort(pin);
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// volatile uint8_t *PIR = portInputRegister(port);
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// EMPTY BUFFER
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memset(dht_bytes, 0, sizeof(uint8_t)*5);
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// REQUEST SAMPLE
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// pinMode(pin, OUTPUT);
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platform_gpio_mode(pin, PLATFORM_GPIO_OUTPUT, PLATFORM_GPIO_PULLUP);
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DIRECT_MODE_OUTPUT(pin);
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// digitalWrite(pin, LOW); // T-be
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DIRECT_WRITE_LOW(pin);
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// delay(wakeupDelay);
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for (i = 0; i < wakeupDelay; i++) os_delay_us(1000);
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// Disable interrupts
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ets_intr_lock();
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// digitalWrite(pin, HIGH); // T-go
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DIRECT_WRITE_HIGH(pin);
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os_delay_us(40);
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// pinMode(pin, INPUT);
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DIRECT_MODE_INPUT(pin);
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// GET ACKNOWLEDGE or TIMEOUT
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uint16_t loopCntLOW = DHTLIB_TIMEOUT;
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while (DIRECT_READ(pin) == LOW ) // T-rel
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{
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os_delay_us(1);
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if (--loopCntLOW == 0) return DHTLIB_ERROR_TIMEOUT;
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}
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uint16_t loopCntHIGH = DHTLIB_TIMEOUT;
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while (DIRECT_READ(pin) != LOW ) // T-reh
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{
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os_delay_us(1);
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if (--loopCntHIGH == 0) return DHTLIB_ERROR_TIMEOUT;
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}
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// READ THE OUTPUT - 40 BITS => 5 BYTES
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for (i = 40; i != 0; i--)
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{
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loopCntLOW = DHTLIB_TIMEOUT;
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while (DIRECT_READ(pin) == LOW )
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{
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os_delay_us(1);
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if (--loopCntLOW == 0) return DHTLIB_ERROR_TIMEOUT;
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}
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uint32_t t = system_get_time();
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loopCntHIGH = DHTLIB_TIMEOUT;
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while (DIRECT_READ(pin) != LOW )
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{
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os_delay_us(1);
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if (--loopCntHIGH == 0) return DHTLIB_ERROR_TIMEOUT;
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}
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if ((system_get_time() - t) > 40)
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{
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dht_bytes[idx] |= mask;
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}
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mask >>= 1;
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if (mask == 0) // next byte?
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{
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mask = 128;
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idx++;
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}
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}
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// Enable interrupts
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ets_intr_unlock();
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// pinMode(pin, OUTPUT);
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DIRECT_MODE_OUTPUT(pin);
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// digitalWrite(pin, HIGH);
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DIRECT_WRITE_HIGH(pin);
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return DHTLIB_OK;
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}
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//
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// END OF FILE
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//
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