ESP8266-12 Blynk Wireless Temperature LM35 Sensor





Introduction: ESP8266-12 Blynk Wireless Temperature LM35 Sensor

ESP8266-12 blynk wireless temperature LM35 sensor

in this project using a esp8266, to show the temperature LM35 sensor on your smartphone or tablet.

if you have available sensors DHT11 DHT22 or you can use the following Instructable

DHT11 sensor

ESP8266-12 blynk wireless temperature, humidity DHT 11 sensor

DHT22 sensor

ESP8266-12 blynk wireless temperature, humidity DHT22 sensor

Step 1: Materials

ESP8266-12 (esp8266-7, ...... , esp8266-12e)

LM35 temperature sensor (10mv /°c)

power regulator 3,3v-5v

Step 2: Connections


VCC +3,3v

CH-PD +3.3v

ADC ---- pin2 (LM35)

GND ground

GPIO5 ground


LM35 sensor

pin 1 +3,3v

pin 2 output .---- ADC (ESP8266-12)

pin 3 ground


Step 3: Blynk App


store app

Blynk Apple Store

Blynk Google Play store


configure blynk

create new project ( use hardware model esp8266 )

generate AUTH TOKEN

send E-mail TOKEN ( copy TOKEN in the esp8266 sketch)

in the app Blynk use Value Display widget or Gauge widget

Step 4: Sketch


blynk library
SimpleTimer library


to programming the ESP8266-12, I use ide arduino 1.6.5 and CP2102 3.3V USB To UART Serial Interface Module Adaptor ( do not connect the power of the CP2102 to esp8266-12).


SP8266 sketch

change the sketch in the following lines with your data

char auth[] = "xxxxxxxxxx"; //insert here your token generated by Blynk

Blynk.begin(auth, "ssid", "password!"); //insert here your SSID and password



If you use ide arduino ADC ---- pin 17

range voltage 0-1.0v

range units 0-1024

Step 5: Thanks

thanks by catoplepa

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Please be positive and constructive.




Nice one! Do you have any idea about how much power it consumes? From my understanding the ESP 12 shouldn't go above 200mA, but the ESP-01 has peeks over 300mA... and my batteries goes crazy in transmissions :(

Other wireless temperature example

My values are out of whack when I use the equation 1/1024 * 100. At 19 deg c, I get values around 12.00 for the temperature and around 125 for the analogRead on the tempPin.

The sensor works properly without the ESP on an Arduino.

Any ideas what might be causing this?

2 replies

Just some details.

The output voltage from the sensor seems to be right (~190mV at 19 deg C). However, when I measure the voltage from ADC pin to GND pin on the ESP-12F, it's around 130mV (also indicated by the analogRead function)-- which seems a bit far from the 1V-1024 conversion.

For some reason, 1.5V instead of 1V seems to be an appropriate conversion in my case but I have no idea why -- I know that ADC pin goes from 0 to 1V (or should at least).

Hi you wrote GPIO5 to GND but on the pic GPIO15 is grounded?

please make one with ds18b20 sensor on a digital pin.!!

Hello all, problem solved.

It seems that it is very important to place home made functions in front of
void setup() and
void loop()

Hi, kyuubi87

Please check that you have library SimpleTimer in the folder


Hi, clebrw

Please check that you have library SimpleTimer in the folder


1 reply

I have the same problem at compile

"error: 'sendUptime' was not declared in this scope"

i have everything in same folder :-(

Farenheit = (Celsius*1.8)+32

Yeah, it works. thank you catoplepa.

What i have to change in the code to get Celsius and not Farenheit?

OK thank's

I wish there was a sketch for DS18B20.

I'll be waiting I believe will be written.

Hi Homerruma

not because the two sensors are completely different, LM35 is an analog sensor while DS18b20 is a digital sensor.

the DS18b20 is certainly compatible with both Blynk that ESP8266 but that created a new sketch


Is it possible to replace the LM35 sensor with DS18B20?

I'm sorry but I do not know what it means


When I try to load the sketch, after a few seconds, the message appears.

I use a 3.3V 3A capable.

I tried many baud rates...

But I finally I found that the module is in 74880 bauds! Yes 74880.

When I power it I receive these 2 lines :

ets Jan 8 2013,rst cause:1, boot mode:(7,3)

waiting for host

But there is no 74880 baud rate in arduino IDE.

Any idea of what does this message means?

Thanks a lot.

Hi, whogarden

It happens while loading the sketch or after?

you can try to put the Baud rate 9600

Also check, that you have sufficient power (3.3 V).

and check your wiring


With the sketch below, I have the error :

warning: espcomm_sync failed
error: espcomm_open failed

And no answer to AT command.

Any idea about baud rate?

Something else?