Fork of DHT repo with checksum fixes.
Fork of DHT by
DHT.cpp@1:932d451474dc, 2014-04-19 (annotated)
- Committer:
- moisesmarangoni
- Date:
- Sat Apr 19 18:05:38 2014 +0000
- Revision:
- 1:932d451474dc
- Parent:
- 0:9b5b3200688f
- Child:
- 2:e7b0a41eecac
First realease DHT working with Nucleo Board. Thanks (Somlak Mangnimit)
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
Wimpie | 0:9b5b3200688f | 1 | /* |
Wimpie | 0:9b5b3200688f | 2 | * DHT Library for Digital-output Humidity and Temperature sensors |
Wimpie | 0:9b5b3200688f | 3 | * |
moisesmarangoni | 1:932d451474dc | 4 | * Works with DHT11, DHT22 Nucleo Board tested on F103RB |
Wimpie | 0:9b5b3200688f | 5 | * |
moisesmarangoni | 1:932d451474dc | 6 | * Copyright (C) Wim De Roeve |
moisesmarangoni | 1:932d451474dc | 7 | * ported to work on Nucleo Board: |
moisesmarangoni | 1:932d451474dc | 8 | * Moises Marangoni |
moisesmarangoni | 1:932d451474dc | 9 | * Somlak Mangnimit |
Wimpie | 0:9b5b3200688f | 10 | * based on DHT22 sensor library by HO WING KIT |
Wimpie | 0:9b5b3200688f | 11 | * Arduino DHT11 library |
Wimpie | 0:9b5b3200688f | 12 | */ |
Wimpie | 0:9b5b3200688f | 13 | |
Wimpie | 0:9b5b3200688f | 14 | #include "DHT.h" |
moisesmarangoni | 1:932d451474dc | 15 | #include "mbed.h" |
Wimpie | 0:9b5b3200688f | 16 | |
Wimpie | 0:9b5b3200688f | 17 | #define DHT_DATA_BIT_COUNT 41 |
Wimpie | 0:9b5b3200688f | 18 | |
moisesmarangoni | 1:932d451474dc | 19 | //DigitalInOut data_pin(PA_10); |
moisesmarangoni | 1:932d451474dc | 20 | |
Wimpie | 0:9b5b3200688f | 21 | DHT::DHT(PinName pin,int DHTtype) { |
Wimpie | 0:9b5b3200688f | 22 | _pin = pin; |
Wimpie | 0:9b5b3200688f | 23 | _DHTtype = DHTtype; |
moisesmarangoni | 1:932d451474dc | 24 | |
moisesmarangoni | 1:932d451474dc | 25 | |
Wimpie | 0:9b5b3200688f | 26 | } |
Wimpie | 0:9b5b3200688f | 27 | |
Wimpie | 0:9b5b3200688f | 28 | DHT::~DHT() { |
Wimpie | 0:9b5b3200688f | 29 | } |
Wimpie | 0:9b5b3200688f | 30 | |
Wimpie | 0:9b5b3200688f | 31 | int DHT::readData() { |
moisesmarangoni | 1:932d451474dc | 32 | Timer tmr; |
moisesmarangoni | 1:932d451474dc | 33 | DigitalInOut data_pin(_pin); |
moisesmarangoni | 1:932d451474dc | 34 | // BUFFER TO RECEIVE |
moisesmarangoni | 1:932d451474dc | 35 | //uint8_t bits[5]; |
moisesmarangoni | 1:932d451474dc | 36 | uint8_t cnt = 7; |
moisesmarangoni | 1:932d451474dc | 37 | uint8_t idx = 0; |
moisesmarangoni | 1:932d451474dc | 38 | |
moisesmarangoni | 1:932d451474dc | 39 | tmr.stop(); |
moisesmarangoni | 1:932d451474dc | 40 | tmr.reset(); |
Wimpie | 0:9b5b3200688f | 41 | |
moisesmarangoni | 1:932d451474dc | 42 | // EMPTY BUFFER |
moisesmarangoni | 1:932d451474dc | 43 | for(int i=0; i< 5; i++) bits[i] = 0; |
Wimpie | 0:9b5b3200688f | 44 | |
moisesmarangoni | 1:932d451474dc | 45 | // REQUEST SAMPLE |
moisesmarangoni | 1:932d451474dc | 46 | data_pin.output(); |
moisesmarangoni | 1:932d451474dc | 47 | data_pin.write(0); |
moisesmarangoni | 1:932d451474dc | 48 | wait_ms(18); |
moisesmarangoni | 1:932d451474dc | 49 | data_pin.write(1); |
moisesmarangoni | 1:932d451474dc | 50 | wait_us(40); |
moisesmarangoni | 1:932d451474dc | 51 | data_pin.input(); |
Wimpie | 0:9b5b3200688f | 52 | |
moisesmarangoni | 1:932d451474dc | 53 | // ACKNOWLEDGE or TIMEOUT |
moisesmarangoni | 1:932d451474dc | 54 | unsigned int loopCnt = 10000; |
moisesmarangoni | 1:932d451474dc | 55 | |
moisesmarangoni | 1:932d451474dc | 56 | while(!data_pin.read())if(!loopCnt--)return DHTLIB_ERROR_TIMEOUT; |
Wimpie | 0:9b5b3200688f | 57 | |
moisesmarangoni | 1:932d451474dc | 58 | loopCnt = 10000; |
moisesmarangoni | 1:932d451474dc | 59 | |
moisesmarangoni | 1:932d451474dc | 60 | while(data_pin.read())if(!loopCnt--)return DHTLIB_ERROR_TIMEOUT; |
Wimpie | 0:9b5b3200688f | 61 | |
moisesmarangoni | 1:932d451474dc | 62 | // READ OUTPUT - 40 BITS => 5 BYTES or TIMEOUT |
moisesmarangoni | 1:932d451474dc | 63 | for(int i=0; i<40; i++){ |
moisesmarangoni | 1:932d451474dc | 64 | |
moisesmarangoni | 1:932d451474dc | 65 | loopCnt = 10000; |
moisesmarangoni | 1:932d451474dc | 66 | |
moisesmarangoni | 1:932d451474dc | 67 | while(!data_pin.read())if(loopCnt-- == 0)return DHTLIB_ERROR_TIMEOUT; |
moisesmarangoni | 1:932d451474dc | 68 | |
moisesmarangoni | 1:932d451474dc | 69 | //unsigned long t = micros(); |
moisesmarangoni | 1:932d451474dc | 70 | tmr.start(); |
Wimpie | 0:9b5b3200688f | 71 | |
moisesmarangoni | 1:932d451474dc | 72 | loopCnt = 10000; |
moisesmarangoni | 1:932d451474dc | 73 | |
moisesmarangoni | 1:932d451474dc | 74 | while(data_pin.read())if(!loopCnt--)return DHTLIB_ERROR_TIMEOUT; |
Wimpie | 0:9b5b3200688f | 75 | |
moisesmarangoni | 1:932d451474dc | 76 | if(tmr.read_us() > 40) bits[idx] |= (1 << cnt); |
moisesmarangoni | 1:932d451474dc | 77 | |
moisesmarangoni | 1:932d451474dc | 78 | tmr.stop(); |
moisesmarangoni | 1:932d451474dc | 79 | tmr.reset(); |
moisesmarangoni | 1:932d451474dc | 80 | |
moisesmarangoni | 1:932d451474dc | 81 | if(cnt == 0){ // next byte? |
moisesmarangoni | 1:932d451474dc | 82 | |
moisesmarangoni | 1:932d451474dc | 83 | cnt = 7; // restart at MSB |
moisesmarangoni | 1:932d451474dc | 84 | idx++; // next byte! |
moisesmarangoni | 1:932d451474dc | 85 | |
moisesmarangoni | 1:932d451474dc | 86 | }else cnt--; |
moisesmarangoni | 1:932d451474dc | 87 | |
Wimpie | 0:9b5b3200688f | 88 | } |
moisesmarangoni | 1:932d451474dc | 89 | // WRITE TO RIGHT VARS |
moisesmarangoni | 1:932d451474dc | 90 | // as bits[1] and bits[3] are allways zero they are omitted in formulas. |
moisesmarangoni | 1:932d451474dc | 91 | //humidity = bits[0]; |
moisesmarangoni | 1:932d451474dc | 92 | //temperature = bits[2]; |
Wimpie | 0:9b5b3200688f | 93 | |
moisesmarangoni | 1:932d451474dc | 94 | uint8_t sum = bits[0] + bits[2]; |
Wimpie | 0:9b5b3200688f | 95 | |
moisesmarangoni | 1:932d451474dc | 96 | if(bits[4] != sum)return DHTLIB_ERROR_CHECKSUM; |
moisesmarangoni | 1:932d451474dc | 97 | |
moisesmarangoni | 1:932d451474dc | 98 | return DHTLIB_OK; |
Wimpie | 0:9b5b3200688f | 99 | } |
moisesmarangoni | 1:932d451474dc | 100 | float DHT::ReadTemperature() { |
moisesmarangoni | 1:932d451474dc | 101 | //int retornotemp; |
Wimpie | 0:9b5b3200688f | 102 | |
Wimpie | 0:9b5b3200688f | 103 | switch (_DHTtype) { |
Wimpie | 0:9b5b3200688f | 104 | case DHT11: |
moisesmarangoni | 1:932d451474dc | 105 | temperature = bits[2]; |
moisesmarangoni | 1:932d451474dc | 106 | return float(temperature); |
Wimpie | 0:9b5b3200688f | 107 | case DHT22: |
moisesmarangoni | 1:932d451474dc | 108 | temperature = bits[2] & 0x7F; |
moisesmarangoni | 1:932d451474dc | 109 | temperature *= 256; |
moisesmarangoni | 1:932d451474dc | 110 | temperature += bits[3]; |
moisesmarangoni | 1:932d451474dc | 111 | temperature /= 10; |
moisesmarangoni | 1:932d451474dc | 112 | if (bits[2] & 0x80) |
moisesmarangoni | 1:932d451474dc | 113 | {temperature *= -1;} |
moisesmarangoni | 1:932d451474dc | 114 | return float(temperature); |
Wimpie | 0:9b5b3200688f | 115 | } |
Wimpie | 0:9b5b3200688f | 116 | return 0; |
Wimpie | 0:9b5b3200688f | 117 | } |
Wimpie | 0:9b5b3200688f | 118 | |
moisesmarangoni | 1:932d451474dc | 119 | int DHT::ReadHumidity() { |
moisesmarangoni | 1:932d451474dc | 120 | //int v; |
Wimpie | 0:9b5b3200688f | 121 | |
Wimpie | 0:9b5b3200688f | 122 | switch (_DHTtype) { |
Wimpie | 0:9b5b3200688f | 123 | case DHT11: |
moisesmarangoni | 1:932d451474dc | 124 | humidity = bits[0]; |
moisesmarangoni | 1:932d451474dc | 125 | return float(humidity); |
Wimpie | 0:9b5b3200688f | 126 | case DHT22: |
moisesmarangoni | 1:932d451474dc | 127 | humidity = bits[0]; |
moisesmarangoni | 1:932d451474dc | 128 | humidity *= 256; |
moisesmarangoni | 1:932d451474dc | 129 | humidity += bits[1]; |
moisesmarangoni | 1:932d451474dc | 130 | humidity /= 10; |
moisesmarangoni | 1:932d451474dc | 131 | return float(humidity); |
Wimpie | 0:9b5b3200688f | 132 | } |
Wimpie | 0:9b5b3200688f | 133 | return 0; |
moisesmarangoni | 1:932d451474dc | 134 | } |