akkera 102
/
DHT11_test
DHT11(Temp and Humidity sensor) test
main.cpp@1:89cfea395009, 2014-12-16 (annotated)
- Committer:
- akkera102
- Date:
- Tue Dec 16 16:36:17 2014 +0000
- Revision:
- 1:89cfea395009
- Parent:
- 0:7780b0dfed46
dht11
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
akkera102 | 0:7780b0dfed46 | 1 | /* |
akkera102 | 0:7780b0dfed46 | 2 | * 2014/12/16 Modified by akkera102 |
akkera102 | 0:7780b0dfed46 | 3 | * |
akkera102 | 0:7780b0dfed46 | 4 | * DHT Library for Digital-output Humidity and Temperature sensors |
akkera102 | 0:7780b0dfed46 | 5 | * |
akkera102 | 0:7780b0dfed46 | 6 | * Works with DHT11 |
akkera102 | 0:7780b0dfed46 | 7 | * SEN11301P, Grove - Temperature&Humidity Sensor (Seeed Studio) |
akkera102 | 0:7780b0dfed46 | 8 | * |
akkera102 | 0:7780b0dfed46 | 9 | * Copyright (C) Wim De Roeve |
akkera102 | 0:7780b0dfed46 | 10 | * based on DHT22 sensor library by HO WING KIT |
akkera102 | 0:7780b0dfed46 | 11 | * Arduino DHT11 library |
akkera102 | 0:7780b0dfed46 | 12 | * |
akkera102 | 0:7780b0dfed46 | 13 | * Permission is hereby granted, free of charge, to any person obtaining a copy |
akkera102 | 0:7780b0dfed46 | 14 | * of this software and associated documnetation files (the "Software"), to deal |
akkera102 | 0:7780b0dfed46 | 15 | * in the Software without restriction, including without limitation the rights |
akkera102 | 0:7780b0dfed46 | 16 | * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
akkera102 | 0:7780b0dfed46 | 17 | * copies of the Software, and to permit persons to whom the Software is |
akkera102 | 0:7780b0dfed46 | 18 | * furished to do so, subject to the following conditions: |
akkera102 | 0:7780b0dfed46 | 19 | * |
akkera102 | 0:7780b0dfed46 | 20 | * The above copyright notice and this permission notice shall be included in |
akkera102 | 0:7780b0dfed46 | 21 | * all copies or substantial portions of the Software. |
akkera102 | 0:7780b0dfed46 | 22 | * |
akkera102 | 0:7780b0dfed46 | 23 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
akkera102 | 0:7780b0dfed46 | 24 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
akkera102 | 0:7780b0dfed46 | 25 | * FITNESS OR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
akkera102 | 0:7780b0dfed46 | 26 | * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
akkera102 | 0:7780b0dfed46 | 27 | * LIABILITY WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
akkera102 | 0:7780b0dfed46 | 28 | * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
akkera102 | 0:7780b0dfed46 | 29 | * THE SOFTWARE. |
akkera102 | 0:7780b0dfed46 | 30 | */ |
akkera102 | 0:7780b0dfed46 | 31 | |
akkera102 | 0:7780b0dfed46 | 32 | #include "mbed.h" |
akkera102 | 0:7780b0dfed46 | 33 | |
akkera102 | 0:7780b0dfed46 | 34 | Serial pc(USBTX, USBRX); |
akkera102 | 0:7780b0dfed46 | 35 | DigitalInOut pin(p8); |
akkera102 | 0:7780b0dfed46 | 36 | |
akkera102 | 0:7780b0dfed46 | 37 | enum { |
akkera102 | 0:7780b0dfed46 | 38 | SUCCESS, |
akkera102 | 0:7780b0dfed46 | 39 | ERROR_TIMEOUT, |
akkera102 | 0:7780b0dfed46 | 40 | ERROR_BUS_BUSY, |
akkera102 | 0:7780b0dfed46 | 41 | ERROR_NOT_PRESENT, |
akkera102 | 0:7780b0dfed46 | 42 | ERROR_NO_PATIENCE, |
akkera102 | 0:7780b0dfed46 | 43 | ERROR_SYNC_TIMEOUT, |
akkera102 | 0:7780b0dfed46 | 44 | ERROR_DATA_TIMEOUT, |
akkera102 | 0:7780b0dfed46 | 45 | ERROR_CHECKSUM |
akkera102 | 0:7780b0dfed46 | 46 | }; |
akkera102 | 0:7780b0dfed46 | 47 | |
akkera102 | 0:7780b0dfed46 | 48 | float Temperature; |
akkera102 | 0:7780b0dfed46 | 49 | float Humidity; |
akkera102 | 0:7780b0dfed46 | 50 | |
akkera102 | 0:7780b0dfed46 | 51 | |
akkera102 | 0:7780b0dfed46 | 52 | int Stall(int usTimeMax, int level) |
akkera102 | 0:7780b0dfed46 | 53 | { |
akkera102 | 0:7780b0dfed46 | 54 | int usTime = 0; |
akkera102 | 0:7780b0dfed46 | 55 | |
akkera102 | 0:7780b0dfed46 | 56 | while(usTime < usTimeMax) |
akkera102 | 0:7780b0dfed46 | 57 | { |
akkera102 | 0:7780b0dfed46 | 58 | if(pin == level) |
akkera102 | 0:7780b0dfed46 | 59 | { |
akkera102 | 0:7780b0dfed46 | 60 | return SUCCESS; |
akkera102 | 0:7780b0dfed46 | 61 | } |
akkera102 | 0:7780b0dfed46 | 62 | |
akkera102 | 0:7780b0dfed46 | 63 | usTime++; |
akkera102 | 0:7780b0dfed46 | 64 | wait_us(1); |
akkera102 | 0:7780b0dfed46 | 65 | } |
akkera102 | 0:7780b0dfed46 | 66 | |
akkera102 | 0:7780b0dfed46 | 67 | return ERROR_TIMEOUT; |
akkera102 | 0:7780b0dfed46 | 68 | } |
akkera102 | 0:7780b0dfed46 | 69 | |
akkera102 | 0:7780b0dfed46 | 70 | int WaitPinHigh(int usTimeOut) |
akkera102 | 0:7780b0dfed46 | 71 | { |
akkera102 | 0:7780b0dfed46 | 72 | return Stall(usTimeOut, 1); |
akkera102 | 0:7780b0dfed46 | 73 | } |
akkera102 | 0:7780b0dfed46 | 74 | |
akkera102 | 0:7780b0dfed46 | 75 | int WaitPinLow(int usTimeOut) |
akkera102 | 0:7780b0dfed46 | 76 | { |
akkera102 | 0:7780b0dfed46 | 77 | return Stall(usTimeOut, 0); |
akkera102 | 0:7780b0dfed46 | 78 | } |
akkera102 | 0:7780b0dfed46 | 79 | |
akkera102 | 0:7780b0dfed46 | 80 | int ReadDHT11(void) |
akkera102 | 0:7780b0dfed46 | 81 | { |
akkera102 | 0:7780b0dfed46 | 82 | // IO must be in hi state to start |
akkera102 | 0:7780b0dfed46 | 83 | if(WaitPinHigh(250) == ERROR_TIMEOUT) |
akkera102 | 0:7780b0dfed46 | 84 | { |
akkera102 | 0:7780b0dfed46 | 85 | return ERROR_BUS_BUSY; |
akkera102 | 0:7780b0dfed46 | 86 | } |
akkera102 | 0:7780b0dfed46 | 87 | |
akkera102 | 0:7780b0dfed46 | 88 | // start the transfer |
akkera102 | 0:7780b0dfed46 | 89 | pin.output(); |
akkera102 | 0:7780b0dfed46 | 90 | pin = 0; |
akkera102 | 0:7780b0dfed46 | 91 | wait_ms(18); |
akkera102 | 0:7780b0dfed46 | 92 | |
akkera102 | 0:7780b0dfed46 | 93 | pin = 1; |
akkera102 | 0:7780b0dfed46 | 94 | wait_us(30); |
akkera102 | 0:7780b0dfed46 | 95 | |
akkera102 | 0:7780b0dfed46 | 96 | pin.input(); |
akkera102 | 0:7780b0dfed46 | 97 | |
akkera102 | 0:7780b0dfed46 | 98 | // wait till the sensor grabs the bus |
akkera102 | 0:7780b0dfed46 | 99 | if(WaitPinLow(40) == ERROR_TIMEOUT) |
akkera102 | 0:7780b0dfed46 | 100 | { |
akkera102 | 0:7780b0dfed46 | 101 | return ERROR_NOT_PRESENT; |
akkera102 | 0:7780b0dfed46 | 102 | } |
akkera102 | 0:7780b0dfed46 | 103 | |
akkera102 | 0:7780b0dfed46 | 104 | // sensor should signal low 80us and then hi 80us |
akkera102 | 0:7780b0dfed46 | 105 | if(WaitPinHigh(100) == ERROR_TIMEOUT) |
akkera102 | 0:7780b0dfed46 | 106 | { |
akkera102 | 0:7780b0dfed46 | 107 | return ERROR_SYNC_TIMEOUT; |
akkera102 | 0:7780b0dfed46 | 108 | } |
akkera102 | 0:7780b0dfed46 | 109 | if(WaitPinLow(100) == ERROR_TIMEOUT) |
akkera102 | 0:7780b0dfed46 | 110 | { |
akkera102 | 0:7780b0dfed46 | 111 | return ERROR_NO_PATIENCE; |
akkera102 | 0:7780b0dfed46 | 112 | } |
akkera102 | 0:7780b0dfed46 | 113 | |
akkera102 | 0:7780b0dfed46 | 114 | int i, bit; |
akkera102 | 0:7780b0dfed46 | 115 | uint8_t buf[5]; |
akkera102 | 0:7780b0dfed46 | 116 | |
akkera102 | 0:7780b0dfed46 | 117 | // capture the data(40 bit) |
akkera102 | 0:7780b0dfed46 | 118 | for(i=0; i<5; i++) |
akkera102 | 0:7780b0dfed46 | 119 | { |
akkera102 | 0:7780b0dfed46 | 120 | buf[i] = 0; |
akkera102 | 0:7780b0dfed46 | 121 | |
akkera102 | 0:7780b0dfed46 | 122 | for(bit=0; bit<8; bit++) |
akkera102 | 0:7780b0dfed46 | 123 | { |
akkera102 | 0:7780b0dfed46 | 124 | if(WaitPinHigh(75) == ERROR_TIMEOUT) |
akkera102 | 0:7780b0dfed46 | 125 | { |
akkera102 | 0:7780b0dfed46 | 126 | return ERROR_DATA_TIMEOUT; |
akkera102 | 0:7780b0dfed46 | 127 | } |
akkera102 | 0:7780b0dfed46 | 128 | |
akkera102 | 0:7780b0dfed46 | 129 | // logic 0 is 28us max, 1 is 70us |
akkera102 | 0:7780b0dfed46 | 130 | wait_us(40); |
akkera102 | 0:7780b0dfed46 | 131 | buf[i] |= pin << (7 - bit); |
akkera102 | 0:7780b0dfed46 | 132 | |
akkera102 | 0:7780b0dfed46 | 133 | if(WaitPinLow(50) == ERROR_TIMEOUT) |
akkera102 | 0:7780b0dfed46 | 134 | { |
akkera102 | 0:7780b0dfed46 | 135 | return ERROR_DATA_TIMEOUT; |
akkera102 | 0:7780b0dfed46 | 136 | } |
akkera102 | 0:7780b0dfed46 | 137 | } |
akkera102 | 0:7780b0dfed46 | 138 | } |
akkera102 | 0:7780b0dfed46 | 139 | |
akkera102 | 0:7780b0dfed46 | 140 | for(i=0; i<5; i++) |
akkera102 | 0:7780b0dfed46 | 141 | { |
akkera102 | 0:7780b0dfed46 | 142 | printf("buf[%d] = 0x%02x\n", i, buf[i]); |
akkera102 | 0:7780b0dfed46 | 143 | } |
akkera102 | 0:7780b0dfed46 | 144 | |
akkera102 | 0:7780b0dfed46 | 145 | // valid check |
akkera102 | 0:7780b0dfed46 | 146 | if(buf[4] != buf[0] + buf[1] + buf[2] + buf[3]) |
akkera102 | 0:7780b0dfed46 | 147 | { |
akkera102 | 0:7780b0dfed46 | 148 | return ERROR_CHECKSUM; |
akkera102 | 0:7780b0dfed46 | 149 | } |
akkera102 | 0:7780b0dfed46 | 150 | |
akkera102 | 0:7780b0dfed46 | 151 | Temperature = float(buf[2]); |
akkera102 | 0:7780b0dfed46 | 152 | Humidity = float(buf[0]); |
akkera102 | 0:7780b0dfed46 | 153 | |
akkera102 | 0:7780b0dfed46 | 154 | return SUCCESS; |
akkera102 | 0:7780b0dfed46 | 155 | } |
akkera102 | 0:7780b0dfed46 | 156 | |
akkera102 | 0:7780b0dfed46 | 157 | int main(void) |
akkera102 | 0:7780b0dfed46 | 158 | { |
akkera102 | 0:7780b0dfed46 | 159 | int ret; |
akkera102 | 0:7780b0dfed46 | 160 | |
akkera102 | 0:7780b0dfed46 | 161 | for(;;) |
akkera102 | 0:7780b0dfed46 | 162 | { |
akkera102 | 0:7780b0dfed46 | 163 | ret = ReadDHT11(); |
akkera102 | 0:7780b0dfed46 | 164 | |
akkera102 | 0:7780b0dfed46 | 165 | if(ret == SUCCESS) |
akkera102 | 0:7780b0dfed46 | 166 | { |
akkera102 | 0:7780b0dfed46 | 167 | printf("Temperature : %4.2f\n", Temperature); |
akkera102 | 0:7780b0dfed46 | 168 | printf("Humidity : %4.2f\n", Humidity); |
akkera102 | 0:7780b0dfed46 | 169 | } |
akkera102 | 0:7780b0dfed46 | 170 | else |
akkera102 | 0:7780b0dfed46 | 171 | { |
akkera102 | 1:89cfea395009 | 172 | printf("Error : %d\n", ret); |
akkera102 | 0:7780b0dfed46 | 173 | } |
akkera102 | 0:7780b0dfed46 | 174 | |
akkera102 | 0:7780b0dfed46 | 175 | wait(2); |
akkera102 | 0:7780b0dfed46 | 176 | } |
akkera102 | 0:7780b0dfed46 | 177 | } |