Mercurial > mbsePi-apps / file comparison
comparison: dht11/dht11.c
dht11/dht11.c
- changeset 51
- a03b6dac5398
- parent 35
- f3c5ae78b746
- child 146
- 11f431ac253d
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| 50:8b5e8f1e172d | 51:a03b6dac5398 |
|---|---|
| 18 * You should have received a copy of the GNU General Public License | 18 * You should have received a copy of the GNU General Public License |
| 19 * along with EC-65K; see the file COPYING. If not, write to the Free | 19 * along with EC-65K; see the file COPYING. If not, write to the Free |
| 20 * Software Foundation, 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. | 20 * Software Foundation, 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. |
| 21 *****************************************************************************/ | 21 *****************************************************************************/ |
| 22 | 22 |
| 23 #include "../lib/mbselib.h" | |
| 24 #include "dht11.h" | 23 #include "dht11.h" |
| 25 | 24 |
| 26 #ifdef HAVE_WIRINGPI_H | 25 #ifdef HAVE_WIRINGPI_H |
| 27 | 26 |
| 28 extern int dht11_valid; | 27 #define MAXTIMINGS 100 |
| 29 extern int dht11_temperature; | 28 |
| 30 extern int dht11_humidity; | 29 int dht11_pin = -1; |
| 30 int dht11_temperature = -1; | |
| 31 int dht11_humidity = -1; | |
| 32 int dht11_valid = false; | |
| 33 int dht11_t_offset = 0; | |
| 34 int dht11_h_offset = 0; | |
| 35 | |
| 36 | |
| 37 | |
| 38 static uint8_t sizecvt(const int read_value) { | |
| 39 /* | |
| 40 * digitalRead() and friends from wiringpi are defined as returning a value | |
| 41 * < 256. However, they are returned as int() types. This is a safety function | |
| 42 */ | |
| 43 if (read_value > 255 || read_value < 0) { | |
| 44 syslog(LOG_NOTICE, "invalid data from wiringPi library"); | |
| 45 } | |
| 46 | |
| 47 return (uint8_t)read_value; | |
| 48 } | |
| 49 | |
| 50 | |
| 51 | |
| 52 /* | |
| 53 * DHT11 sensor read. This should be used in a thread loop. | |
| 54 */ | |
| 55 void dht11Read(void) { | |
| 56 int tries = 5; | |
| 57 unsigned short got_correct_data = 0; | |
| 58 | |
| 59 if (dht11_pin == -1) | |
| 60 return; | |
| 61 | |
| 62 while (tries && !got_correct_data) { | |
| 63 uint8_t laststate = HIGH; | |
| 64 uint8_t counter = 0; | |
| 65 uint8_t j = 0, i = 0; | |
| 66 int dht11_dat[5] = {0,0,0,0,0}; | |
| 67 | |
| 68 /* | |
| 69 * Select output mode to send the start signal. | |
| 70 */ | |
| 71 pinMode(dht11_pin, OUTPUT); | |
| 72 digitalWrite(dht11_pin, HIGH); | |
| 73 usleep(1000); | |
| 74 | |
| 75 /* | |
| 76 * Low for at least 18 milliseconds | |
| 77 */ | |
| 78 digitalWrite(dht11_pin, LOW); | |
| 79 usleep(20000); | |
| 80 digitalWrite(dht11_pin, HIGH); | |
| 81 pinMode(dht11_pin, INPUT); | |
| 82 | |
| 83 /* | |
| 84 * Detect change and read data | |
| 85 */ | |
| 86 for (i=0; i<MAXTIMINGS; i++) { | |
| 87 counter = 0; | |
| 88 delayMicroseconds(10); | |
| 89 while (sizecvt(digitalRead(dht11_pin)) == laststate) { | |
| 90 counter++; | |
| 91 delayMicroseconds(1); | |
| 92 if (counter == 255) { | |
| 93 break; | |
| 94 } | |
| 95 } | |
| 96 laststate = sizecvt(digitalRead(dht11_pin)); | |
| 97 | |
| 98 if (counter == 255) | |
| 99 break; | |
| 100 | |
| 101 /* | |
| 102 * ignore first 3 transitions | |
| 103 */ | |
| 104 if ((i >= 4) && (i%2 == 0)) { | |
| 105 | |
| 106 // shove each bit into the storage bytes | |
| 107 dht11_dat[(int)((double)j/8)] <<= 1; | |
| 108 if (counter > 16) | |
| 109 dht11_dat[(int)((double)j/8)] |= 1; | |
| 110 j++; | |
| 111 } | |
| 112 } | |
| 113 | |
| 114 /* | |
| 115 * If there is no sensor, j = 0 | |
| 116 */ | |
| 117 if ((counter == 255) && (j == 0)) { | |
| 118 if (dht11_temperature != -1) { | |
| 119 syslog(LOG_NOTICE, "dht11 sensor disappeared"); | |
| 120 } else { | |
| 121 syslog(LOG_NOTICE, "dht11 sensor not present"); | |
| 122 } | |
| 123 dht11_temperature = -1; | |
| 124 dht11_humidity = -1; | |
| 125 dht11_valid = false; | |
| 126 return; | |
| 127 } | |
| 128 | |
| 129 /* | |
| 130 * check we read 40 bits (8bit x 5 ) + verify checksum in the last byte | |
| 131 * print it out if data is good | |
| 132 */ | |
| 133 if ((j >= 40) && (dht11_dat[4] == ((dht11_dat[0] + dht11_dat[1] + dht11_dat[2] + dht11_dat[3]) & 0xFF))) { | |
| 134 got_correct_data = 1; | |
| 135 | |
| 136 int h = dht11_dat[0] + dht11_dat[1]; | |
| 137 int t = (dht11_dat[2] & 0x7F) + dht11_dat[3]; | |
| 138 t += dht11_t_offset; | |
| 139 h += dht11_h_offset; | |
| 140 | |
| 141 if ((dht11_dat[2] & 0x80) != 0) | |
| 142 t *= -1; | |
| 143 | |
| 144 dht11_temperature = t; | |
| 145 dht11_humidity = h; | |
| 146 dht11_valid = true; | |
| 147 } else { | |
| 148 tries--; | |
| 149 if (tries == 0) | |
| 150 syslog(LOG_INFO, "dht11 data checksum was wrong 5 times"); | |
| 151 usleep(100000); | |
| 152 } | |
| 153 } | |
| 154 } | |
| 155 | |
| 156 | |
| 157 | |
| 158 void dht11Init(int pin, int t_offset, int h_offset) { | |
| 159 dht11_pin = pin; | |
| 160 dht11_t_offset = t_offset; | |
| 161 dht11_h_offset = h_offset; | |
| 162 } | |
| 163 | |
| 164 | |
| 31 | 165 |
| 32 int main(int argc, char *argv[]) { | 166 int main(int argc, char *argv[]) { |
| 33 | 167 |
| 34 int PIN = 3; | 168 int PIN = 3; |
| 35 | 169 |
