DHT library problem

I used the example code from DHT library and the following error popped up.

Processing  dhttester.ino
Checking library DHT...
Installing library DHT 1.3.0 to lib/DHT ...
Library DHT 1.3.0 installed.
make -C ../modules/photon/user-part all
make[1]: Entering directory '/firmware/modules/photon/user-part'
make -C ../../../user 
make[2]: Entering directory '/firmware/user'
Building cpp file: src/dhttester.cpp
Invoking: ARM GCC CPP Compiler
mkdir -p ../build/target/user/platform-6-msrc/
arm-none-eabi-gcc -DSTM32_DEVICE -DSTM32F2XX -DPLATFORM_THREADING=1 -DPLATFORM_ID=6 -DPLATFORM_NAME=photon -DPLATFORM_GEN=2 -DUSBD_VID_SPARK=0x2B04 -DUSBD_PID_DFU=0xD006 -DUSBD_PID_CDC=0xC006 -DSPARK_PLATFORM -g3 -gdwarf-2 -Os -mcpu=cortex-m3 -mthumb --specs=nano.specs -DINCLUDE_PLATFORM=1 -DPRODUCT_ID=6 -DPRODUCT_FIRMWARE_VERSION=65535 -DUSE_STDPERIPH_DRIVER -DDFU_BUILD_ENABLE -DSYSTEM_VERSION_STRING=2.0.1 -DRELEASE_BUILD -I./inc -I../wiring/inc -I../system/inc -I../services/inc -I../third_party/nanopb/nanopb -I../communication/inc -I../hal/inc -I../hal/shared -I../hal/src/photon -I../hal/src/stm32f2xx -I../hal/src/stm32 -I../hal/network/util -I../hal/network -I../hal/src/photon/api -I../hal/src/photon/include -I../hal/src/photon/wiced/security/BESL/host/WICED/ -I../hal/src/photon/wiced/security/BESL/include -I../hal/src/photon/wiced/security/BESL -I../hal/src/photon/wiced/security/BESL/crypto -I../hal/src/photon/wiced/WWD/include/ -I../hal/src/photon/wiced/platform/include/ -I../hal/src/photon/wiced/platform/GCC/ -I../hal/src/photon/wiced/security/BESL/supplicant/ -I../hal/src/photon/libraries/crypto -I../hal/src/photon/libraries/daemons/DNS_redirect -I../third_party/miniz/miniz -I../platform/shared/inc -I../platform/MCU/STM32F2xx/STM32_USB_Host_Driver/inc -I../platform/MCU/STM32F2xx/STM32_USB_OTG_Driver/inc -I../platform/MCU/STM32F2xx/STM32_StdPeriph_Driver/inc -I../platform/MCU/STM32F2xx/STM32_USB_Device_Driver/inc -I../platform/MCU/STM32F2xx/SPARK_Firmware_Driver/inc -I../platform/MCU/shared/STM32/inc -I../platform/MCU/STM32F2xx/CMSIS/Include -I../platform/MCU/STM32F2xx/CMSIS/Device/ST/Include -I../dynalib/inc -Isrc -I./libraries -Ilib/DHT/src -I. -MD -MP -MF ../build/target/user/platform-6-msrc/dhttester.o.d -ffunction-sections -fdata-sections -Wall -Wno-switch -Wno-error=deprecated-declarations -fmessage-length=0 -fno-strict-aliasing -DSPARK=1 -DPARTICLE=1 -Wundef -DSTART_DFU_FLASHER_SERIAL_SPEED=14400 -DSTART_YMODEM_FLASHER_SERIAL_SPEED=28800 -DBOOTLOADER_SDK_3_3_0_PARTICLE -DPARTICLE_DCT_COMPATIBILITY -DSPARK_PLATFORM_NET=BCM9WCDUSI09 -fno-builtin-malloc -fno-builtin-free -fno-builtin-realloc  -DLOG_INCLUDE_SOURCE_INFO=1 -DPARTICLE_USER_MODULE -DUSER_FIRMWARE_IMAGE_SIZE=0x20000 -DUSER_FIRMWARE_IMAGE_LOCATION=0x80A0000 -DMODULAR_FIRMWARE=1 -DMODULE_VERSION=6 -DMODULE_FUNCTION=5 -DMODULE_INDEX=1 -DMODULE_DEPENDENCY=4,2,2011 -DMODULE_DEPENDENCY2=0,0,0 -D_GNU_SOURCE -DLOG_MODULE_CATEGORY="\"app\""  -fno-exceptions -fno-rtti -fcheck-new -std=gnu++14 -c -o ../build/target/user/platform-6-msrc/dhttester.o src/dhttester.cpp
In file included from dhttester.ino:4:
lib/DHT/src/DHT.h:9:5: warning: "ARDUINO" is not defined, evaluates to 0 [-Wundef]
    9 | #if ARDUINO >= 100
      |     ^~~~~~~

Building cpp file: lib/DHT/src/DHT.cpp
Invoking: ARM GCC CPP Compiler
mkdir -p ../build/target/user/platform-6-mDHT/src/
arm-none-eabi-gcc -DSTM32_DEVICE -DSTM32F2XX -DPLATFORM_THREADING=1 -DPLATFORM_ID=6 -DPLATFORM_NAME=photon -DPLATFORM_GEN=2 -DUSBD_VID_SPARK=0x2B04 -DUSBD_PID_DFU=0xD006 -DUSBD_PID_CDC=0xC006 -DSPARK_PLATFORM -g3 -gdwarf-2 -Os -mcpu=cortex-m3 -mthumb --specs=nano.specs -DINCLUDE_PLATFORM=1 -DPRODUCT_ID=6 -DPRODUCT_FIRMWARE_VERSION=65535 -DUSE_STDPERIPH_DRIVER -DDFU_BUILD_ENABLE -DSYSTEM_VERSION_STRING=2.0.1 -DRELEASE_BUILD -I./inc -I../wiring/inc -I../system/inc -I../services/inc -I../third_party/nanopb/nanopb -I../communication/inc -I../hal/inc -I../hal/shared -I../hal/src/photon -I../hal/src/stm32f2xx -I../hal/src/stm32 -I../hal/network/util -I../hal/network -I../hal/src/photon/api -I../hal/src/photon/include -I../hal/src/photon/wiced/security/BESL/host/WICED/ -I../hal/src/photon/wiced/security/BESL/include -I../hal/src/photon/wiced/security/BESL -I../hal/src/photon/wiced/security/BESL/crypto -I../hal/src/photon/wiced/WWD/include/ -I../hal/src/photon/wiced/platform/include/ -I../hal/src/photon/wiced/platform/GCC/ -I../hal/src/photon/wiced/security/BESL/supplicant/ -I../hal/src/photon/libraries/crypto -I../hal/src/photon/libraries/daemons/DNS_redirect -I../third_party/miniz/miniz -I../platform/shared/inc -I../platform/MCU/STM32F2xx/STM32_USB_Host_Driver/inc -I../platform/MCU/STM32F2xx/STM32_USB_OTG_Driver/inc -I../platform/MCU/STM32F2xx/STM32_StdPeriph_Driver/inc -I../platform/MCU/STM32F2xx/STM32_USB_Device_Driver/inc -I../platform/MCU/STM32F2xx/SPARK_Firmware_Driver/inc -I../platform/MCU/shared/STM32/inc -I../platform/MCU/STM32F2xx/CMSIS/Include -I../platform/MCU/STM32F2xx/CMSIS/Device/ST/Include -I../dynalib/inc -Isrc -I./libraries -Ilib/DHT/src -I. -MD -MP -MF ../build/target/user/platform-6-mDHT/src/DHT.o.d -ffunction-sections -fdata-sections -Wall -Wno-switch -Wno-error=deprecated-declarations -fmessage-length=0 -fno-strict-aliasing -DSPARK=1 -DPARTICLE=1 -Wundef -DSTART_DFU_FLASHER_SERIAL_SPEED=14400 -DSTART_YMODEM_FLASHER_SERIAL_SPEED=28800 -DBOOTLOADER_SDK_3_3_0_PARTICLE -DPARTICLE_DCT_COMPATIBILITY -DSPARK_PLATFORM_NET=BCM9WCDUSI09 -fno-builtin-malloc -fno-builtin-free -fno-builtin-realloc  -DLOG_INCLUDE_SOURCE_INFO=1 -DPARTICLE_USER_MODULE -DUSER_FIRMWARE_IMAGE_SIZE=0x20000 -DUSER_FIRMWARE_IMAGE_LOCATION=0x80A0000 -DMODULAR_FIRMWARE=1 -DMODULE_VERSION=6 -DMODULE_FUNCTION=5 -DMODULE_INDEX=1 -DMODULE_DEPENDENCY=4,2,2011 -DMODULE_DEPENDENCY2=0,0,0 -D_GNU_SOURCE -DLOG_MODULE_CATEGORY="\"app\""  -fno-exceptions -fno-rtti -fcheck-new -std=gnu++14 -c -o ../build/target/user/platform-6-mDHT/src/DHT.o lib/DHT/src/DHT.cpp
In file included from lib/DHT/src/DHT.cpp:7:
lib/DHT/src/DHT.h:9:5: warning: "ARDUINO" is not defined, evaluates to 0 [-Wundef]
    9 | #if ARDUINO >= 100
      |     ^~~~~~~

Building cpp file: lib/DHT/src/DHT_U.cpp
Invoking: ARM GCC CPP Compiler
mkdir -p ../build/target/user/platform-6-mDHT/src/
arm-none-eabi-gcc -DSTM32_DEVICE -DSTM32F2XX -DPLATFORM_THREADING=1 -DPLATFORM_ID=6 -DPLATFORM_NAME=photon -DPLATFORM_GEN=2 -DUSBD_VID_SPARK=0x2B04 -DUSBD_PID_DFU=0xD006 -DUSBD_PID_CDC=0xC006 -DSPARK_PLATFORM -g3 -gdwarf-2 -Os -mcpu=cortex-m3 -mthumb --specs=nano.specs -DINCLUDE_PLATFORM=1 -DPRODUCT_ID=6 -DPRODUCT_FIRMWARE_VERSION=65535 -DUSE_STDPERIPH_DRIVER -DDFU_BUILD_ENABLE -DSYSTEM_VERSION_STRING=2.0.1 -DRELEASE_BUILD -I./inc -I../wiring/inc -I../system/inc -I../services/inc -I../third_party/nanopb/nanopb -I../communication/inc -I../hal/inc -I../hal/shared -I../hal/src/photon -I../hal/src/stm32f2xx -I../hal/src/stm32 -I../hal/network/util -I../hal/network -I../hal/src/photon/api -I../hal/src/photon/include -I../hal/src/photon/wiced/security/BESL/host/WICED/ -I../hal/src/photon/wiced/security/BESL/include -I../hal/src/photon/wiced/security/BESL -I../hal/src/photon/wiced/security/BESL/crypto -I../hal/src/photon/wiced/WWD/include/ -I../hal/src/photon/wiced/platform/include/ -I../hal/src/photon/wiced/platform/GCC/ -I../hal/src/photon/wiced/security/BESL/supplicant/ -I../hal/src/photon/libraries/crypto -I../hal/src/photon/libraries/daemons/DNS_redirect -I../third_party/miniz/miniz -I../platform/shared/inc -I../platform/MCU/STM32F2xx/STM32_USB_Host_Driver/inc -I../platform/MCU/STM32F2xx/STM32_USB_OTG_Driver/inc -I../platform/MCU/STM32F2xx/STM32_StdPeriph_Driver/inc -I../platform/MCU/STM32F2xx/STM32_USB_Device_Driver/inc -I../platform/MCU/STM32F2xx/SPARK_Firmware_Driver/inc -I../platform/MCU/shared/STM32/inc -I../platform/MCU/STM32F2xx/CMSIS/Include -I../platform/MCU/STM32F2xx/CMSIS/Device/ST/Include -I../dynalib/inc -Isrc -I./libraries -Ilib/DHT/src -I. -MD -MP -MF ../build/target/user/platform-6-mDHT/src/DHT_U.o.d -ffunction-sections -fdata-sections -Wall -Wno-switch -Wno-error=deprecated-declarations -fmessage-length=0 -fno-strict-aliasing -DSPARK=1 -DPARTICLE=1 -Wundef -DSTART_DFU_FLASHER_SERIAL_SPEED=14400 -DSTART_YMODEM_FLASHER_SERIAL_SPEED=28800 -DBOOTLOADER_SDK_3_3_0_PARTICLE -DPARTICLE_DCT_COMPATIBILITY -DSPARK_PLATFORM_NET=BCM9WCDUSI09 -fno-builtin-malloc -fno-builtin-free -fno-builtin-realloc  -DLOG_INCLUDE_SOURCE_INFO=1 -DPARTICLE_USER_MODULE -DUSER_FIRMWARE_IMAGE_SIZE=0x20000 -DUSER_FIRMWARE_IMAGE_LOCATION=0x80A0000 -DMODULAR_FIRMWARE=1 -DMODULE_VERSION=6 -DMODULE_FUNCTION=5 -DMODULE_INDEX=1 -DMODULE_DEPENDENCY=4,2,2011 -DMODULE_DEPENDENCY2=0,0,0 -D_GNU_SOURCE -DLOG_MODULE_CATEGORY="\"app\""  -fno-exceptions -fno-rtti -fcheck-new -std=gnu++14 -c -o ../build/target/user/platform-6-mDHT/src/DHT_U.o lib/DHT/src/DHT_U.cpp
In file included from lib/DHT/src/DHT_U.cpp:22:
lib/DHT/src/DHT_U.h:25:10: fatal error: Adafruit_Sensor.h: No such file or directory
   25 | #include <Adafruit_Sensor.h>
      |          ^~~~~~~~~~~~~~~~~~~
compilation terminated.
../build/module.mk:286: recipe for target '../build/target/user/platform-6-mDHT/src/DHT_U.o' failed
make[2]: *** [../build/target/user/platform-6-mDHT/src/DHT_U.o] Error 1
make[2]: Leaving directory '/firmware/user'
../../../build/recurse.mk:11: recipe for target 'user' failed
make[1]: *** [user] Error 2
make[1]: Leaving directory '/firmware/modules/photon/user-part'
../build/recurse.mk:11: recipe for target 'modules/photon/user-part' failed
make: *** [modules/photon/user-part] Error 2

The code I used:

// Example testing sketch for various DHT humidity/temperature sensors
// Written by ladyada, public domain

#include "DHT.h"

#define DHTPIN 2     // what digital pin we're connected to

// Uncomment whatever type you're using!
//#define DHTTYPE DHT11   // DHT 11
#define DHTTYPE DHT22   // DHT 22  (AM2302), AM2321
//#define DHTTYPE DHT21   // DHT 21 (AM2301)

// Connect pin 1 (on the left) of the sensor to +5V
// NOTE: If using a board with 3.3V logic like an Arduino Due connect pin 1
// to 3.3V instead of 5V!
// Connect pin 2 of the sensor to whatever your DHTPIN is
// Connect pin 4 (on the right) of the sensor to GROUND
// Connect a 10K resistor from pin 2 (data) to pin 1 (power) of the sensor

// Initialize DHT sensor.
// Note that older versions of this library took an optional third parameter to
// tweak the timings for faster processors.  This parameter is no longer needed
// as the current DHT reading algorithm adjusts itself to work on faster procs.
DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(9600);
  Serial.println("DHTxx test!");

  dht.begin();
}

void loop() {
  // Wait a few seconds between measurements.
  delay(2000);

  // Reading temperature or humidity takes about 250 milliseconds!
  // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
  float h = dht.readHumidity();
  // Read temperature as Celsius (the default)
  float t = dht.readTemperature();
  // Read temperature as Fahrenheit (isFahrenheit = true)
  float f = dht.readTemperature(true);

  // Check if any reads failed and exit early (to try again).
  if (isnan(h) || isnan(t) || isnan(f)) {
    Serial.println("Failed to read from DHT sensor!");
    return;
  }

  // Compute heat index in Fahrenheit (the default)
  float hif = dht.computeHeatIndex(f, h);
  // Compute heat index in Celsius (isFahreheit = false)
  float hic = dht.computeHeatIndex(t, h, false);

  Serial.print("Humidity: ");
  Serial.print(h);
  Serial.print(" %\t");
  Serial.print("Temperature: ");
  Serial.print(t);
  Serial.print(" *C ");
  Serial.print(f);
  Serial.print(" *F\t");
  Serial.print("Heat index: ");
  Serial.print(hic);
  Serial.print(" *C ");
  Serial.print(hif);
  Serial.println(" *F");
}

I used web editor to verify the example code.

If you #include “Particle.h” before the include for “DHT.h” then the ARDUINO not defined should disappear.

With the DHT I believe the pierretech library works/works better than the Adafruit version.

I did #include “Particle.h” the same error popped up. I used PietteTech_DHT library instead and it is working fine now.

Good to hear. Can you please mark as Solved.