for: ESP8266 + DHTXX + deepsleep + battery monitor + OTA + Blynk by: Truglodite
Deepsleeps, wakes after "sleepMicros" (10min default), and sends Temperature (F), Humidity (%), Heat Index (F), Wifi RSSI (dBm), and battery level (V) to a Blynk server. When battery voltage drops below "vbattLow", data and a notification are sent every 70min. When the battery voltage drops below a set critical threshold, data and a notification are sent, and the esp goes to deepsleep until battery is removed/replaced (deepsleep(0)).
If the app Firmware button is turned on and battery is not low, when the esp next awakens it will send a notification and stay on to wait for an ArduinoOTA upload. Do not turn the firmware button off while uploading. You may turn off the firmware button to resume normal operation after upload/reboot and second notification is sent. If you accidentally hit the firmware button, you may turn it off before uploading... it will send current data and resume normal operation. If the FW button is on longer than "otaTimeout", it will restart to send a reminder notification. If b
Power to the DHT sensor is controlled by io5. The DHT is turned off while asleep to save battery. Note that the DHT is an appreciable capacitive load, so low quiescent LDO's may have trouble with voltage spike resets. A somewhat large bypass cap may be required for stability; note that some candidate capacitors (ie: electrolytic) have very large leakage current, which can drastically reduce battery life.
Note that you must add a notification widget to the Blynk app for low battery and OTA ready notifications to work. Additional notifications can be added for convenience (ie a 'freezing' alert).
Maximize deepsleep time (sleepMinutes) to preserve battery. My experiments lean towards Blynk.begin() as the faster connect. Eliminating unnecessary peripherals (ie LEDs and USB/UART chips), and using low quiescent LDO's (ADP160AU is good) and low leakage capacitors can achieve extreme battery life. For example a 10min sleep time, static IP, and 3000mAh lion can last nearly one year.
| Vpin | Data Output (all user optional... no BLYNK_WRITE()'s here) |
|---|---|
| V0 | Temperature [F] |
| V1 | Relative Humidity [%] |
| V2 | Heat Index [F] |
| V3 | Wifi RSSI [dBm] with 'extraOutput' |
| V4 | Battery Voltage [V] |
| V5 | Firmware Upload Button |
| V6 | Last awake time [msec] |
| V7 | Dew Point [F] |
| ESPpin | Description |
|---|---|
| io4 | DHT sensor data pin |
| io5 | DHT Vcc pin |
| A0 | Battery voltage divider output (default 330k/100k with 1s Li-Ion) |
| EN | 10k High |
| io2 | 10k High |
| io15 | 10k Low |
| io16 | RST - 220ohm resistor link for self-wake from deepsleep |