A minimal library for the DHT11.
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Revision 2:983fdd709bf7, committed 2017-11-09
- Comitter:
- amithy
- Date:
- Thu Nov 09 22:14:56 2017 +0000
- Parent:
- 1:5da6f6de3e42
- Commit message:
- test export
Changed in this revision
--- a/Dht11.cpp Mon Feb 16 01:43:08 2015 +0000 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,89 +0,0 @@ -#include "Dht11.h" - -Dht11::Dht11(PinName const &p) : _pin(p) { - // Set creation time so we can make - // sure we pause at least 1 second for - // startup. - _timer.start(); - - _temperature = 0; - _humidity = 0; -} - -int Dht11::read() -{ - // BUFFER TO RECEIVE - uint8_t bits[5]; - uint8_t cnt = 7; - uint8_t idx = 0; - - // EMPTY BUFFER - for (int i=0; i< 5; i++) bits[i] = 0; - - // Verify sensor settled after boot - while(_timer.read_ms() < 1500) {} - _timer.stop(); - - // Notify it we are ready to read - _pin.output(); - _pin = 0; - wait_ms(18); - _pin = 1; - wait_us(40); - _pin.input(); - - // ACKNOWLEDGE or TIMEOUT - unsigned int loopCnt = 10000; - while(_pin == 0) - if (loopCnt-- == 0) return DHTLIB_ERROR_TIMEOUT; - - loopCnt = 10000; - while(_pin == 1) - if (loopCnt-- == 0) return DHTLIB_ERROR_TIMEOUT; - - // READ OUTPUT - 40 BITS => 5 BYTES or TIMEOUT - for (int i=0; i<40; i++) - { - loopCnt = 10000; - while(_pin == 0) - if (loopCnt-- == 0) return DHTLIB_ERROR_TIMEOUT; - - //unsigned long t = micros(); - Timer t; - t. start(); - - loopCnt = 10000; - while(_pin == 1) - if (loopCnt-- == 0) return DHTLIB_ERROR_TIMEOUT; - - if (t.read_us() > 40) bits[idx] |= (1 << cnt); - if (cnt == 0) // next byte? - { - cnt = 7; // restart at MSB - idx++; // next byte! - } - else cnt--; - } - - // WRITE TO RIGHT VARS - // as bits[1] and bits[3] are allways zero they are omitted in formulas. - _humidity = bits[0]; - _temperature = bits[2]; - - uint8_t sum = bits[0] + bits[2]; - - if (bits[4] != sum) return DHTLIB_ERROR_CHECKSUM; - return DHTLIB_OK; -} - -float Dht11::getFahrenheit() { - return((_temperature * 1.8) + 32); -} - -int Dht11::getCelsius() { - return(_temperature); -} - -int Dht11::getHumidity() { - return(_humidity); -}
--- a/Dht11.h Mon Feb 16 01:43:08 2015 +0000 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,74 +0,0 @@ -#ifndef DHT11_H -#define DHT11_H - -#include "mbed.h" - -#define DHTLIB_OK 0 -#define DHTLIB_ERROR_CHECKSUM -1 -#define DHTLIB_ERROR_TIMEOUT -2 - -/** Class for the DHT11 sensor. - * - * Example: - * @code - * #include "mbed.h" - * #include "Dht11.h" - * - * Serial pc(USBTX, USBRX); - * Dht11 sensor(PTD7); - * - * int main() { - * sensor.read() - * pc.printf("T: %f, H: %d\r\n", sensor.getFahrenheit(), sensor.getHumidity()); - * } - * @endcode - */ -class Dht11 -{ -public: - /** Construct the sensor object. - * - * @param pin PinName for the sensor pin. - */ - Dht11(PinName const &p); - - /** Update the humidity and temp from the sensor. - * - * @returns - * 0 on success, otherwise error. - */ - int read(); - - /** Get the temp(f) from the saved object. - * - * @returns - * Fahrenheit float - */ - float getFahrenheit(); - - /** Get the temp(c) from the saved object. - * - * @returns - * Celsius int - */ - int getCelsius(); - - /** Get the humidity from the saved object. - * - * @returns - * Humidity percent int - */ - int getHumidity(); - -private: - /// percentage of humidity - int _humidity; - /// celsius - int _temperature; - /// pin to read the sensor info on - DigitalInOut _pin; - /// times startup (must settle for at least a second) - Timer _timer; -}; - -#endif
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/Dht22.cpp Thu Nov 09 22:14:56 2017 +0000 @@ -0,0 +1,104 @@ +#include "Dht22.h" + +Dht22::Dht22(PinName const &p) : _pin(p) { + // Set creation time so we can make + // sure we pause at least 1 second for + // startup. + _timer.start(); + + _temperature = 0; + _humidity = 0; +} + +int Dht22::read() +{ + // BUFFER TO RECEIVE + uint8_t bits[5]; + uint8_t cnt = 7; + uint8_t idx = 0; + + // EMPTY BUFFER + for (int i=0; i< 5; i++) bits[i] = 0; + + // Verify sensor settled after boot + while(_timer.read_ms() < 1500) {} + _timer.stop(); + + // Notify it we are ready to read + _pin.output(); + _pin = 0; + wait_ms(18); + _pin = 1; + wait_us(40); + _pin.input(); + + // ACKNOWLEDGE or TIMEOUT + unsigned int loopCnt = 10000; + while(_pin == 0) + if (loopCnt-- == 0) return DHTLIB_ERROR_TIMEOUT; + + loopCnt = 10000; + while(_pin == 1) + if (loopCnt-- == 0) return DHTLIB_ERROR_TIMEOUT; + + // READ OUTPUT - 40 BITS => 5 BYTES or TIMEOUT + for (int i=0; i<40; i++) + { + loopCnt = 10000; + while(_pin == 0) + if (loopCnt-- == 0) return DHTLIB_ERROR_TIMEOUT; + + //unsigned long t = micros(); + Timer t; + t. start(); + + loopCnt = 10000; + while(_pin == 1) + if (loopCnt-- == 0) return DHTLIB_ERROR_TIMEOUT; + + if (t.read_us() > 40) bits[idx] |= (1 << cnt); + if (cnt == 0) // next byte? + { + cnt = 7; // restart at MSB + idx++; // next byte! + } + else cnt--; + } + +// // WRITE TO RIGHT VARS - DHT22 +// // as bits[1] and bits[3] are allways zero they are omitted in formulas. +// _humidity = bits[0]; +// _temperature = bits[2]; +// +// uint8_t sum = bits[0] + bits[2]; +// +// if (bits[4] != sum) return DHTLIB_ERROR_CHECKSUM; + + + uint8_t dht22_check_sum; + dht22_check_sum = bits[0] + bits[1] + bits[2] + bits[3]; + //printf("dht22 check sum: %d",dht22_check_sum); + dht22_check_sum= dht22_check_sum%256; + //printf("dht22 check sum: %d",dht22_check_sum); + + if (dht22_check_sum == bits[4]) { + _humidity = bits[0]*256 + bits[1]; + + _temperature = bits[2]*256 + bits[3]; + //printf("all good \n"); + return DHTLIB_OK; + } + return DHTLIB_ERROR_CHECKSUM; +} + +float Dht22::getFahrenheit() { + return((_temperature * 1.8) + 32); +} + +int Dht22::getCelsius() { + return(_temperature); +} + +int Dht22::getHumidity() { + return(_humidity); +}
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/Dht22.h Thu Nov 09 22:14:56 2017 +0000 @@ -0,0 +1,74 @@ +#ifndef DHT22_H +#define DHT22_H + +#include "mbed.h" + +#define DHTLIB_OK 0 +#define DHTLIB_ERROR_CHECKSUM -1 +#define DHTLIB_ERROR_TIMEOUT -2 + +/** Class for the DHT22 sensor. + * + * Example: + * @code + * #include "mbed.h" + * #include "Dht22.h" + * + * Serial pc(USBTX, USBRX); + * Dht22 sensor(PTD7); + * + * int main() { + * sensor.read() + * pc.printf("T: %f, H: %d\r\n", sensor.getFahrenheit(), sensor.getHumidity()); + * } + * @endcode + */ +class Dht22 +{ +public: + /** Construct the sensor object. + * + * @param pin PinName for the sensor pin. + */ + Dht22(PinName const &p); + + /** Update the humidity and temp from the sensor. + * + * @returns + * 0 on success, otherwise error. + */ + int read(); + + /** Get the temp(f) from the saved object. + * + * @returns + * Fahrenheit float + */ + float getFahrenheit(); + + /** Get the temp(c) from the saved object. + * + * @returns + * Celsius int + */ + int getCelsius(); + + /** Get the humidity from the saved object. + * + * @returns + * Humidity percent int + */ + int getHumidity(); + +private: + /// percentage of humidity + int _humidity; + /// celsius + int _temperature; + /// pin to read the sensor info on + DigitalInOut _pin; + /// times startup (must settle for at least a second) + Timer _timer; +}; + +#endif
--- a/mbed.bld Mon Feb 16 01:43:08 2015 +0000 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,1 +0,0 @@ -http://mbed.org/users/mbed_official/code/mbed/builds/e188a91d3eaa \ No newline at end of file