Added DHT11 library and demo code

main/DHT11.c

@@ -0,0 +1,194 @@
+/* DHT11 temperature sensor library
+
+   Usage is straight forward:
+   		Ser DHT PIN using  setDHTPin(pin) command
+   		then use any of the getter functions to get temp/humidity data
+
+   Sam Johnston 
+   October 2016
+   This example code is in the Public Domain (or CC0 licensed, at your option.)
+
+   Unless required by applicable law or agreed to in writing, this
+   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+   CONDITIONS OF ANY KIND, either express or implied.
+*/
+
+#include <stdio.h>
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "esp_system.h"
+#include "rom/ets_sys.h"
+#include "nvs_flash.h"
+#include "driver/gpio.h"
+#include "sdkconfig.h"
+#include "DHT11.h"
+
+
+int humidity = 0;
+int temperature = 0;
+int Ftemperature = 0;
+int DHT_PIN = 4;
+
+void setDHTPin(int PIN)
+{
+	DHT_PIN = PIN;
+}
+void errorHandle(int response)
+{
+	switch(response) {
+
+		case DHT_TIMEOUT_ERROR :
+			printf("DHT Sensor Timeout!\n");
+		case DHT_CHECKSUM_ERROR:
+			printf("CheckSum error!\n");
+		case DHT_OKAY:
+			break;
+		default :
+			printf("Dont know how you got here!\n");
+	}
+	temperature = 0;
+	humidity = 0;
+
+}
+void sendStart()
+{
+  //Send start signal from ESP32 to DHT device
+  gpio_set_direction(DHT_PIN, GPIO_MODE_OUTPUT);
+  gpio_set_level(DHT_PIN,0);
+  //vTaskDelay(36 / portTICK_RATE_MS);
+  ets_delay_us(22000);
+  gpio_set_level(DHT_PIN,1);
+  ets_delay_us(43);
+  gpio_set_direction(DHT_PIN, GPIO_MODE_INPUT);
+}
+
+int getData()
+{
+  //Variables used in this function
+  int counter = 0;
+  uint8_t bits[5];
+  uint8_t byteCounter = 0;
+  uint8_t cnt = 7;
+
+  for (int i = 0; i <5; i++)
+  {
+  	bits[i] = 0;
+  }
+
+  sendStart();
+
+  //Wait for a response from the DHT11 device
+  //This requires waiting for 20-40 us 
+  counter = 0;
+
+  while (gpio_get_level(DHT_PIN)==1)
+  {
+      if(counter > 40)
+      {
+      	return DHT_TIMEOUT_ERROR;
+      }	
+      counter = counter + 1;
+      ets_delay_us(1);
+  }
+  //Now that the DHT has pulled the line low, 
+  //it will keep the line low for 80 us and then high for 80us
+  //check to see if it keeps low
+  counter = 0;
+  while(gpio_get_level(DHT_PIN)==0)
+  {
+  	if(counter > 80)
+  	{
+  		return DHT_TIMEOUT_ERROR;
+  	}
+  	counter = counter + 1;
+  	ets_delay_us(1);
+  }
+  counter = 0;
+  while(gpio_get_level(DHT_PIN)==1)
+  {
+  	if(counter > 80)
+  	{
+  		return DHT_TIMEOUT_ERROR;
+  	}
+  	counter = counter + 1;
+  	ets_delay_us(1);
+  }
+  // If no errors have occurred, it is time to read data
+  //output data from the DHT11 is 40 bits.
+  //Loop here until 40 bits have been read or a timeout occurs
+
+  for(int i = 0; i < 40; i++)
+  {
+      //int currentBit = 0;
+      //starts new data transmission with 50us low signal
+      counter = 0;
+      while(gpio_get_level(DHT_PIN)==0)
+  	  {
+  	  	if (counter > 55)
+  	  	{
+  	  	   return DHT_TIMEOUT_ERROR; 
+  	  	}
+  	  	counter = counter + 1;
+  	  	ets_delay_us(1);
+  	  }
+
+  	  //Now check to see if new data is a 0 or a 1
+      counter = 0;
+      while(gpio_get_level(DHT_PIN)==1)
+  	  {
+  	  	if (counter > 75)
+  	  	{
+  	  	   return DHT_TIMEOUT_ERROR; 
+  	  	}
+  	  	counter = counter + 1;
+  	  	ets_delay_us(1);
+  	  }  	  
+  	  //add the current reading to the output data
+  	  //since all bits where set to 0 at the start of the loop, only looking for 1s
+  	  //look for when count is greater than 40 - this allows for some margin of error
+  	  if (counter > 40)
+  	  {
+
+  	  	bits[byteCounter] |= (1 << cnt);
+
+  	  }
+  	  //here are conditionals that work with the bit counters
+  	  if (cnt == 0)
+  	  {
+
+  	  	cnt = 7;
+  	  	byteCounter = byteCounter +1;
+  	  }else{
+
+  	  	cnt = cnt -1;
+  	  } 	  
+  }
+  humidity = bits[0];
+  temperature = bits[2];
+  Ftemperature = temperature * 1.8 + 32;
+
+  uint8_t sum = bits[0] + bits[2];
+
+  if (bits[4] != sum)
+  {
+  	return DHT_CHECKSUM_ERROR;
+  }
+  return DHT_OKAY;
+}
+
+int getFtemp()
+{
+
+	getData();
+	return Ftemperature;	
+}
+int getTemp()
+{
+	getData();
+	return temperature;
+}
+int getHumidity()
+{
+	getData();
+	return humidity;
+}

main/DHT11.h

@@ -0,0 +1,34 @@
+/* DHT11 temperature sensor library
+
+   Usage is straight forward:
+   		Ser DHT PIN using  setDHTPin(pin) command
+   		then use any of the getter functions to get temp/humidity data
+
+   Sam Johnston 
+   October 2016
+   This example code is in the Public Domain (or CC0 licensed, at your option.)
+
+   Unless required by applicable law or agreed to in writing, this
+   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+   CONDITIONS OF ANY KIND, either express or implied.
+*/
+#ifndef DHT11_H_  
+#define DHT11_H_
+
+#define DHT_TIMEOUT_ERROR -2
+#define DHT_CHECKSUM_ERROR -1
+#define DHT_OKAY  0
+
+// function prototypes
+
+//Start by using this function
+void setDHTPin(int PIN);
+//Do not need to touch these three
+void sendStart();
+int getData();
+void errorHandle(int response);
+//call each function for live temperature updates
+int getFtemp();
+int getTemp();
+int getHumidity();
+#endif

main/DHT_Testing.c

@@ -0,0 +1,34 @@
+//DHT11 sensor reading 
+
+#include <stdio.h>
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "esp_system.h"
+#include "rom/ets_sys.h"
+#include "nvs_flash.h"
+#include "driver/gpio.h"
+#include "sdkconfig.h"
+#include "DHT11.h"
+
+void DHT_task(void *pvParameter)
+{
+   setDHTPin(4);
+   printf("Starting DHT measurement!\n");
+   while(1)
+   {
+    printf("Temperature reading %d\n",getTemp());
+    printf("F temperature is %d\n", getFtemp());
+    printf("Humidity reading %d\n",getHumidity());
+    vTaskDelay(3000 / portTICK_RATE_MS);
+    //sendStart(4);
+   }
+}
+
+void app_main()
+{
+    nvs_flash_init();
+    system_init();
+    vTaskDelay(1000 / portTICK_RATE_MS);
+    xTaskCreate(&DHT_task, "DHT_task", 2048, NULL, 5, NULL);
+}
+