Ro Led / Mbed 2 deprecated Nucleo_DHT11_Sensor_Example

This is an example program to fetch data of DHT11 Sensors

Dependencies:   mbed

Fork of DHT11_with_Nucleo by Adatgy2014

main.cpp@8:01e3281451e2, 2015-01-06 (annotated)

Committer:
kaliczp
Date:
Tue Jan 06 11:33:45 2015 +0000
Revision:
8:01e3281451e2
Parent:
7:5b0793a2b391
Parent:
6:8027edc2b69f
Child:
9:a2918c6c37ee
Some formatting of the DHT11 data.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
kaliczp 0:e8a1a503d390 1 #include "mbed.h"
kaliczp 0:e8a1a503d390 2
kaliczp 2:4469aa7f4995 3 DigitalOut myled(LED1); // Activate LED
kaliczp 2:4469aa7f4995 4 DigitalIn mybutton(USER_BUTTON); // Activate button
kaliczp 2:4469aa7f4995 5 DigitalInOut data_pin(A0); // Activate digital in
kaliczp 4:62b680fac6ed 6 Serial pc(SERIAL_TX, SERIAL_RX); // Initialize UART connection
kaliczp 4:62b680fac6ed 7 // Use a terminal program (eg. TeraTerm).
kaliczp 5:76a9332af64c 8 Timer tmr; //initialize timer
kaliczp 5:76a9332af64c 9 char adat[40]; // Array for data
kaliczp 5:76a9332af64c 10 int i;
kaliczp 0:e8a1a503d390 11
kaliczp 3:6228ab73d420 12 // Function to initialize DHT11
kaliczp 3:6228ab73d420 13 void dht_read(void) {
kaliczp 3:6228ab73d420 14 data_pin.output(); // Set A0 as output
kaliczp 3:6228ab73d420 15 // Initialize measurement > 18 ms low
kaliczp 3:6228ab73d420 16 data_pin = 0;
kaliczp 3:6228ab73d420 17 wait_ms(20);
kaliczp 3:6228ab73d420 18 // After high and release the pin switch input mode
kaliczp 3:6228ab73d420 19 data_pin = 1;
kaliczp 4:62b680fac6ed 20 data_pin.input();
kaliczp 5:76a9332af64c 21 // Wait until the end of 80 us low
kaliczp 5:76a9332af64c 22 while(!data_pin.read()) {}
kaliczp 5:76a9332af64c 23 // Wait until end of 80 us high
kaliczp 5:76a9332af64c 24 while(data_pin.read()) {}
kaliczp 5:76a9332af64c 25 // 40 bit, 40 read out cycle
kaliczp 5:76a9332af64c 26 for(i=0; i<40; i++) {
kaliczp 5:76a9332af64c 27 tmr.stop(); // Stop timer if runs
kaliczp 5:76a9332af64c 28 tmr.reset(); // Reset timer
kaliczp 5:76a9332af64c 29 // Wait until pin
kaliczp 5:76a9332af64c 30 while(!data_pin.read()) {}
kaliczp 5:76a9332af64c 31 tmr.start();
kaliczp 5:76a9332af64c 32 while(data_pin.read()) {}
kaliczp 5:76a9332af64c 33 // If DHT11 HIGH longer than 40 micro seconds (hopefully 70 us)
kaliczp 5:76a9332af64c 34 if(tmr.read_us() > 40) {
kaliczp 5:76a9332af64c 35 // bit is 1
kaliczp 5:76a9332af64c 36 adat[i] = 1;
kaliczp 5:76a9332af64c 37 }
kaliczp 5:76a9332af64c 38 }
kaliczp 3:6228ab73d420 39 }
kaliczp 3:6228ab73d420 40
kaliczp 0:e8a1a503d390 41 int main() {
kaliczp 4:62b680fac6ed 42 pc.printf("Read the DHT11 temperature and humidity sensor!\n"); //Welcome message
kaliczp 0:e8a1a503d390 43 while(1) {
kaliczp 1:c0c5b5860aa8 44 if (mybutton == 0) { // Button is pressed
kaliczp 5:76a9332af64c 45 // Reset character array
kaliczp 5:76a9332af64c 46 for(i=0; i < 40; i++){
kaliczp 5:76a9332af64c 47 adat[i] = 0;
kaliczp 5:76a9332af64c 48 }
kaliczp 1:c0c5b5860aa8 49 myled = 1; // LED is ON
kaliczp 3:6228ab73d420 50 dht_read(); // Call the function
kaliczp 5:76a9332af64c 51 // Send result through UART result
kaliczp 5:76a9332af64c 52 for(i=0; i < 40; i++){
kaliczp 5:76a9332af64c 53 pc.printf("%d",adat[i]);
kaliczp 5:76a9332af64c 54 }
kaliczp 7:5b0793a2b391 55 pc.printf("\n\r"); // Send a new line and carriage return.
kaliczp 2:4469aa7f4995 56 wait_ms(200); // Wait 0.2 sec till continue.
kaliczp 1:c0c5b5860aa8 57 } else {
kaliczp 1:c0c5b5860aa8 58 myled = 0; // LED is OFF
kaliczp 1:c0c5b5860aa8 59 }
kaliczp 0:e8a1a503d390 60 }
kaliczp 0:e8a1a503d390 61 }