129 lines
2.8 KiB
C
129 lines
2.8 KiB
C
/*
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* DTH11 温度湿度传感器
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*
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*/
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#include <wiringPi.h>
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#include <stdio.h>
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#include <string.h>
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#include <stdlib.h>
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#include <stdint.h>
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#include <unistd.h>
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#define MAX_TIME 85
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#define MAX_TRIES 100
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int dht11_val[5] = { 0, 0, 0, 0, 0 };
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int dht11_read_val(int *h, int *t, int pin)
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{
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uint8_t lststate = HIGH;
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uint8_t counter = 0;
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uint8_t j = 0, i;
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for (i = 0; i < 5; i++) {
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dht11_val[i] = 0;
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}
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pinMode(pin, OUTPUT);
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digitalWrite(pin, LOW);
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delay(18);
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digitalWrite(pin, HIGH);
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delayMicroseconds(40);
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pinMode(pin, INPUT);
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for (i = 0; i < MAX_TIME; i++) {
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counter = 0;
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while (digitalRead(pin) == lststate) {
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counter++;
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delayMicroseconds(1);
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if (counter == 255)
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break;
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}
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lststate = digitalRead(pin);
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if (counter == 255)
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break;
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// top 3 transitions are ignored
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if ((i >= 4) && (i % 2 == 0)) {
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dht11_val[j / 8] <<= 1;
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if (counter > 16)
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dht11_val[j / 8] |= 1;
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j++;
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}
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}
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// verify cheksum and print the verified data
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if ((j >= 40)
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&& (dht11_val[4] ==
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((dht11_val[0] + dht11_val[1] + dht11_val[2] +
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dht11_val[3]) & 0xFF))) {
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// Only return the integer part of humidity and temperature. The sensor
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// is not accurate enough for decimals anyway
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*h = dht11_val[0];
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*t = dht11_val[2];
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return 0;
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} else {
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// invalid data
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return 1;
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}
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}
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int is_num(int n, char *argv[])
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{
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int j = 0;
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int i;
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char parameter[10];
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strcpy(parameter, argv[n]);
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int len = strlen(parameter);
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for (i = 0; i < len; i++) {
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if (parameter[i] <= 57 && parameter[i] >= 48) //0~9的ASCII码是48~57
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{
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j++;
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}
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}
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if (j == len) {
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return 1;
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} else {
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return 0;
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}
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}
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int main(int argc, char *argv[])
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{
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if (argc != 2) {
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printf("Parameter error.\n");
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exit(1);
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}
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if (is_num(1, argv) == 0) {
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printf("Parameter error, parameter 1 is PIN pin value\n");
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exit(1);
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}
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int pin = atol(argv[1]);
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int h; //humidity
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int t; //temperature in degrees Celsius
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wiringPiSetup();
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// read the sensor until we get a pair of valid measurements
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// but bail out if we tried too many times
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int retval = 1;
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int tries = 0;
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while (retval != 0 && tries < MAX_TRIES) {
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retval = dht11_read_val(&h, &t, pin);
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if (retval == 0) {
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//printf("%d %d\n", h, t);
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printf("Humidity = %d Temperature = %d ℃ ( %f ℉ )\n", h, t, ((t*1.8)+32));
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} else {
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delay(3000);
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}
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tries += 1;
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}
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if (tries < MAX_TRIES)
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return 0;
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else
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return 1;
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}
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