1 // Copyright (c) 2014 Adafruit Industries

     2 // Author: Tony DiCola

     3 

     4 // Permission is hereby granted, free of charge, to any person obtaining a copy

     5 // of this software and associated documentation files (the "Software"), to deal

     6 // in the Software without restriction, including without limitation the rights

     7 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

     8 // copies of the Software, and to permit persons to whom the Software is

     9 // furnished to do so, subject to the following conditions:

    10 

    11 // The above copyright notice and this permission notice shall be included in all

    12 // copies or substantial portions of the Software.

    13 

    14 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

    15 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

    16 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

    17 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

    18 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

    19 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

    20 // SOFTWARE.

    21 #ifndef COMMON_DHT_READ_H

    22 #define COMMON_DHT_READ_H

    23 

    24 #include <stdint.h>

    25 

    26 // Define errors and return values.

    27 #define DHT_ERROR_TIMEOUT -1

    28 #define DHT_ERROR_CHECKSUM -2

    29 #define DHT_ERROR_ARGUMENT -3

    30 #define DHT_ERROR_GPIO -4

    31 #define DHT_SUCCESS 0

    32 

    33 // Define sensor types.

    34 #define DHT11 11

    35 #define DHT22 22

    36 #define AM2302 22

    37 

    38 // Busy wait delay for most accurate timing, but high CPU usage.

    39 // Only use this for short periods of time (a few hundred milliseconds at most)!

    40 void busy_wait_milliseconds(uint32_t millis);

    41 

    42 // General delay that sleeps so CPU usage is low, but accuracy is potentially bad.

    43 void sleep_milliseconds(uint32_t millis);

    44 

    45 // Increase scheduling priority and algorithm to try to get 'real time' results.

    46 void set_max_priority(void);

    47 

    48 // Drop scheduling priority back to normal/default.

    49 void set_default_priority(void);

    50 

    51 #endif