diff --git a/ESP8266/libraries/DHT.cpp b/ESP8266/libraries/DHT.cpp new file mode 100644 index 0000000..86ad91c --- /dev/null +++ b/ESP8266/libraries/DHT.cpp @@ -0,0 +1,259 @@ +/* DHT library + +MIT license +written by Adafruit Industries +*/ + +#include "DHT.h" + +#define MIN_INTERVAL 2000 + +DHT::DHT(uint8_t pin, uint8_t type, uint8_t count) { + _pin = pin; + _type = type; + #ifdef __AVR + _bit = digitalPinToBitMask(pin); + _port = digitalPinToPort(pin); + #endif + _maxcycles = microsecondsToClockCycles(1000); // 1 millisecond timeout for + // reading pulses from DHT sensor. + // Note that count is now ignored as the DHT reading algorithm adjusts itself + // basd on the speed of the processor. +} + +void DHT::begin(void) { + // set up the pins! + pinMode(_pin, INPUT_PULLUP); + // Using this value makes sure that millis() - lastreadtime will be + // >= MIN_INTERVAL right away. Note that this assignment wraps around, + // but so will the subtraction. + _lastreadtime = -MIN_INTERVAL; + DEBUG_PRINT("Max clock cycles: "); DEBUG_PRINTLN(_maxcycles, DEC); +} + +//boolean S == Scale. True == Fahrenheit; False == Celcius +float DHT::readTemperature(bool S, bool force) { + float f = NAN; + + if (read(force)) { + switch (_type) { + case DHT11: + f = data[2]; + if(S) { + f = convertCtoF(f); + } + break; + case DHT22: + case DHT21: + f = data[2] & 0x7F; + f *= 256; + f += data[3]; + f *= 0.1; + if (data[2] & 0x80) { + f *= -1; + } + if(S) { + f = convertCtoF(f); + } + break; + } + } + return f; +} + +float DHT::convertCtoF(float c) { + return c * 1.8 + 32; +} + +float DHT::convertFtoC(float f) { + return (f - 32) * 0.55555; +} + +float DHT::readHumidity(bool force) { + float f = NAN; + if (read()) { + switch (_type) { + case DHT11: + f = data[0]; + break; + case DHT22: + case DHT21: + f = data[0]; + f *= 256; + f += data[1]; + f *= 0.1; + break; + } + } + return f; +} + +//boolean isFahrenheit: True == Fahrenheit; False == Celcius +float DHT::computeHeatIndex(float temperature, float percentHumidity, bool isFahrenheit) { + // Using both Rothfusz and Steadman's equations + // http://www.wpc.ncep.noaa.gov/html/heatindex_equation.shtml + float hi; + + if (!isFahrenheit) + temperature = convertCtoF(temperature); + + hi = 0.5 * (temperature + 61.0 + ((temperature - 68.0) * 1.2) + (percentHumidity * 0.094)); + + if (hi > 79) { + hi = -42.379 + + 2.04901523 * temperature + + 10.14333127 * percentHumidity + + -0.22475541 * temperature*percentHumidity + + -0.00683783 * pow(temperature, 2) + + -0.05481717 * pow(percentHumidity, 2) + + 0.00122874 * pow(temperature, 2) * percentHumidity + + 0.00085282 * temperature*pow(percentHumidity, 2) + + -0.00000199 * pow(temperature, 2) * pow(percentHumidity, 2); + + if((percentHumidity < 13) && (temperature >= 80.0) && (temperature <= 112.0)) + hi -= ((13.0 - percentHumidity) * 0.25) * sqrt((17.0 - abs(temperature - 95.0)) * 0.05882); + + else if((percentHumidity > 85.0) && (temperature >= 80.0) && (temperature <= 87.0)) + hi += ((percentHumidity - 85.0) * 0.1) * ((87.0 - temperature) * 0.2); + } + + return isFahrenheit ? hi : convertFtoC(hi); +} + +boolean DHT::read(bool force) { + // Check if sensor was read less than two seconds ago and return early + // to use last reading. + uint32_t currenttime = millis(); + if (!force && ((currenttime - _lastreadtime) < 2000)) { + return _lastresult; // return last correct measurement + } + _lastreadtime = currenttime; + + // Reset 40 bits of received data to zero. + data[0] = data[1] = data[2] = data[3] = data[4] = 0; + + // Send start signal. See DHT datasheet for full signal diagram: + // http://www.adafruit.com/datasheets/Digital%20humidity%20and%20temperature%20sensor%20AM2302.pdf + + // Go into high impedence state to let pull-up raise data line level and + // start the reading process. + digitalWrite(_pin, HIGH); + delay(250); + + // First set data line low for 20 milliseconds. + pinMode(_pin, OUTPUT); + digitalWrite(_pin, LOW); + delay(20); + + uint32_t cycles[80]; + { + // Turn off interrupts temporarily because the next sections are timing critical + // and we don't want any interruptions. + InterruptLock lock; + + // End the start signal by setting data line high for 40 microseconds. + digitalWrite(_pin, HIGH); + delayMicroseconds(40); + + // Now start reading the data line to get the value from the DHT sensor. + pinMode(_pin, INPUT_PULLUP); + delayMicroseconds(10); // Delay a bit to let sensor pull data line low. + + // First expect a low signal for ~80 microseconds followed by a high signal + // for ~80 microseconds again. + if (expectPulse(LOW) == 0) { + DEBUG_PRINTLN(F("Timeout waiting for start signal low pulse.")); + _lastresult = false; + return _lastresult; + } + if (expectPulse(HIGH) == 0) { + DEBUG_PRINTLN(F("Timeout waiting for start signal high pulse.")); + _lastresult = false; + return _lastresult; + } + + // Now read the 40 bits sent by the sensor. Each bit is sent as a 50 + // microsecond low pulse followed by a variable length high pulse. If the + // high pulse is ~28 microseconds then it's a 0 and if it's ~70 microseconds + // then it's a 1. We measure the cycle count of the initial 50us low pulse + // and use that to compare to the cycle count of the high pulse to determine + // if the bit is a 0 (high state cycle count < low state cycle count), or a + // 1 (high state cycle count > low state cycle count). Note that for speed all + // the pulses are read into a array and then examined in a later step. + for (int i=0; i<80; i+=2) { + cycles[i] = expectPulse(LOW); + cycles[i+1] = expectPulse(HIGH); + } + } // Timing critical code is now complete. + + // Inspect pulses and determine which ones are 0 (high state cycle count < low + // state cycle count), or 1 (high state cycle count > low state cycle count). + for (int i=0; i<40; ++i) { + uint32_t lowCycles = cycles[2*i]; + uint32_t highCycles = cycles[2*i+1]; + if ((lowCycles == 0) || (highCycles == 0)) { + DEBUG_PRINTLN(F("Timeout waiting for pulse.")); + _lastresult = false; + return _lastresult; + } + data[i/8] <<= 1; + // Now compare the low and high cycle times to see if the bit is a 0 or 1. + if (highCycles > lowCycles) { + // High cycles are greater than 50us low cycle count, must be a 1. + data[i/8] |= 1; + } + // Else high cycles are less than (or equal to, a weird case) the 50us low + // cycle count so this must be a zero. Nothing needs to be changed in the + // stored data. + } + + DEBUG_PRINTLN(F("Received:")); + DEBUG_PRINT(data[0], HEX); DEBUG_PRINT(F(", ")); + DEBUG_PRINT(data[1], HEX); DEBUG_PRINT(F(", ")); + DEBUG_PRINT(data[2], HEX); DEBUG_PRINT(F(", ")); + DEBUG_PRINT(data[3], HEX); DEBUG_PRINT(F(", ")); + DEBUG_PRINT(data[4], HEX); DEBUG_PRINT(F(" =? ")); + DEBUG_PRINTLN((data[0] + data[1] + data[2] + data[3]) & 0xFF, HEX); + + // Check we read 40 bits and that the checksum matches. + if (data[4] == ((data[0] + data[1] + data[2] + data[3]) & 0xFF)) { + _lastresult = true; + return _lastresult; + } + else { + DEBUG_PRINTLN(F("Checksum failure!")); + _lastresult = false; + return _lastresult; + } +} + +// Expect the signal line to be at the specified level for a period of time and +// return a count of loop cycles spent at that level (this cycle count can be +// used to compare the relative time of two pulses). If more than a millisecond +// ellapses without the level changing then the call fails with a 0 response. +// This is adapted from Arduino's pulseInLong function (which is only available +// in the very latest IDE versions): +// https://github.com/arduino/Arduino/blob/master/hardware/arduino/avr/cores/arduino/wiring_pulse.c +uint32_t DHT::expectPulse(bool level) { + uint32_t count = 0; + // On AVR platforms use direct GPIO port access as it's much faster and better + // for catching pulses that are 10's of microseconds in length: + #ifdef __AVR + uint8_t portState = level ? _bit : 0; + while ((*portInputRegister(_port) & _bit) == portState) { + if (count++ >= _maxcycles) { + return 0; // Exceeded timeout, fail. + } + } + // Otherwise fall back to using digitalRead (this seems to be necessary on ESP8266 + // right now, perhaps bugs in direct port access functions?). + #else + while (digitalRead(_pin) == level) { + if (count++ >= _maxcycles) { + return 0; // Exceeded timeout, fail. + } + } + #endif + + return count; +} diff --git a/ESP8266/libraries/DHT.h b/ESP8266/libraries/DHT.h new file mode 100644 index 0000000..d81f6db --- /dev/null +++ b/ESP8266/libraries/DHT.h @@ -0,0 +1,75 @@ +/* DHT library + +MIT license +written by Adafruit Industries +*/ +#ifndef DHT_H +#define DHT_H + +#if ARDUINO >= 100 + #include "Arduino.h" +#else + #include "WProgram.h" +#endif + + +// Uncomment to enable printing out nice debug messages. +//#define DHT_DEBUG + +// Define where debug output will be printed. +#define DEBUG_PRINTER Serial + +// Setup debug printing macros. +#ifdef DHT_DEBUG + #define DEBUG_PRINT(...) { DEBUG_PRINTER.print(__VA_ARGS__); } + #define DEBUG_PRINTLN(...) { DEBUG_PRINTER.println(__VA_ARGS__); } +#else + #define DEBUG_PRINT(...) {} + #define DEBUG_PRINTLN(...) {} +#endif + +// Define types of sensors. +#define DHT11 11 +#define DHT22 22 +#define DHT21 21 +#define AM2301 21 + + +class DHT { + public: + DHT(uint8_t pin, uint8_t type, uint8_t count=6); + void begin(void); + float readTemperature(bool S=false, bool force=false); + float convertCtoF(float); + float convertFtoC(float); + float computeHeatIndex(float temperature, float percentHumidity, bool isFahrenheit=true); + float readHumidity(bool force=false); + boolean read(bool force=false); + + private: + uint8_t data[5]; + uint8_t _pin, _type; + #ifdef __AVR + // Use direct GPIO access on an 8-bit AVR so keep track of the port and bitmask + // for the digital pin connected to the DHT. Other platforms will use digitalRead. + uint8_t _bit, _port; + #endif + uint32_t _lastreadtime, _maxcycles; + bool _lastresult; + + uint32_t expectPulse(bool level); + +}; + +class InterruptLock { + public: + InterruptLock() { + noInterrupts(); + } + ~InterruptLock() { + interrupts(); + } + +}; + +#endif diff --git a/ESP8266/sensornode/sensornode.ino b/ESP8266/sensornode/sensornode.ino index 95c2b6e..4aee3c1 100644 --- a/ESP8266/sensornode/sensornode.ino +++ b/ESP8266/sensornode/sensornode.ino @@ -1,9 +1,69 @@ -void setup() { - // put your setup code here, to run once: +// Example testing sketch for various DHT humidity/temperature sensors +// Written by ladyada, public domain +#include "DHT.h" + +#define DHTPIN 14 // what digital pin we're connected to + +// Uncomment whatever type you're using! +//#define DHTTYPE DHT11 // DHT 11 +#define DHTTYPE DHT22 // DHT 22 (AM2302), AM2321 +//#define DHTTYPE DHT21 // DHT 21 (AM2301) + +// Connect pin 1 (on the left) of the sensor to +5V +// NOTE: If using a board with 3.3V logic like an Arduino Due connect pin 1 +// to 3.3V instead of 5V! +// Connect pin 2 of the sensor to whatever your DHTPIN is +// Connect pin 4 (on the right) of the sensor to GROUND +// Connect a 10K resistor from pin 2 (data) to pin 1 (power) of the sensor + +// Initialize DHT sensor. +// Note that older versions of this library took an optional third parameter to +// tweak the timings for faster processors. This parameter is no longer needed +// as the current DHT reading algorithm adjusts itself to work on faster procs. +DHT dht(DHTPIN, DHTTYPE); + +void setup() { + Serial.begin(115200); + Serial.println("DHTxx test!"); + + dht.begin(); } void loop() { - // put your main code here, to run repeatedly: + // Wait a few seconds between measurements. + delay(2000); -} + // Reading temperature or humidity takes about 250 milliseconds! + // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor) + float h = dht.readHumidity(); + // Read temperature as Celsius (the default) + float t = dht.readTemperature(); + // Read temperature as Fahrenheit (isFahrenheit = true) + float f = dht.readTemperature(true); + + // Check if any reads failed and exit early (to try again). + if (isnan(h) || isnan(t) || isnan(f)) { + Serial.println("Failed to read from DHT sensor!"); + return; + } + + // Compute heat index in Fahrenheit (the default) + float hif = dht.computeHeatIndex(f, h); + // Compute heat index in Celsius (isFahreheit = false) + float hic = dht.computeHeatIndex(t, h, false); + + Serial.print("Humidity: "); + Serial.print(h); + Serial.print(" %\t"); + Serial.print("Temperature: "); + Serial.print(t); + Serial.print(" *C "); + Serial.print(f); + Serial.print(" *F\t"); + Serial.print("Heat index: "); + Serial.print(hic); + Serial.print(" *C "); + Serial.print(hif); + Serial.println(" *F"); +}