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Have you ever wondered how to turn on ESP8266 using external interrupt? Build a battery powered amazon dash button or a 18650 lipo powered door bell using ESP8266 without putting the device in deep sleep? Here is your answer. Idea Keep ESP8266 on OFF mode as default External 3.3V signal (can be short or long) arrives and turns ON ESP8266 ESP8266 wakes up and keeps itself awake until a task is perfomed Send MQTT data to server Put ESP8266 back to power OFF state Implementation RST pin is always HIGH/3.3V using 10k resistor ESP8266 is in OFF state, GPIO0 is low 3.3V signal arrives externally, GPIO0 and CH_PD are high, turn ON ESP8266 First thing ESP8266 does is turns GPIO0 to high, which means CH_PD remain high. So ESP8266 remains ON until GPIO0 is high GPIO12 is used to read value of external interupt If there is 3.3V external interrupt, GPIO is high and a MQTT message is sent as “Signal Received” or “ON” and keep ESP8266 ON until 0V signal is received. If there is 0V external interrupt, GPIO0 goes low and MQTT message is sent as “Signal Vanished” or “OFF” and turns OFF ESP8266 Software This project is built using ideas at http://www.esp8266.com/viewtopic.php?f=11&t=4458 ...

Wouldn’t it be nice to know if your dog’s water bowl is empty? Let us build a sensor that measures the water level every 5 minutes. This value is sent to MQTT server and Home Assistant automation takes care of the rest. This sensor connects to MQTT and Home Assistant. See dogsensor.yaml for adding this to HA. Assumes that one has set up various notification sensors available in HA. ...

Lets turn on and off low powered fan running at low (<20V) DC voltages. We shall use a MOSFET to achieve this. Hardware IRLML0030PBF ATTiny85 2-pin 12V Fan Wiring MOSFETs have three terminals Drain (D), Source (S) and Gate (G), where source is connected to ground and the +12V or +5V along with load (Fan) is connected to drain. The MOSFET is on when gate voltage is higher than 1.7V and turned off when gate voltage is 0V. ...

Here are the instructions to wire a stable AMS1117-3.3 voltage regulator properly. This can power an ESP8266 or any 3.3V micro-controller reliably supporting current draws up to 1A. Hardware AMS 1117-3.3 10 uF Electrolytic Capacitor 104 Ceramic Capacitor Wiring AMS1117-3.3 (right to left) Pin 1: GND Pin 2: Vout Pin 3: Vin Connections 5-12V -> Vin GND -> GND 10 uF Electrolytic Capacitor +ve -> Vout 10 uF Electrolytic Capacitor GND -> GND 104 Ceramic Capacitor +ve -> Vin 104 Ceramic Capacitor GND -> GND

Let’s say that you don’t have your smartphone around and someone mentions you on twitter. Wouldn’t it be nice to have a display that automatically reads your twitter mentions and show it on a scrolling display? So let’s build a internet controlled (IoT) dot-matrix display that does this for us using an ESP8266. ...