Pro mini and low power mode

Projects General Guidance
1

I want to make a thermometer with a DS18B20. I will use either a 1602 LCD or a small OLED to display the temperature. I would like this thing to be connected to a capacitive touch sensor to turn the unit on for x amount of time to view then go back to low power mode.

Is this project feasible to be powered by a 2S LiPo and not have to worry about charging the unit every few days? I'm thinking somewhere between 500 and 1000mAh capacity LiPo.

2

A Pro Mini can be powered by a single LiPo cell, or less efficiently, using two.

See this excellent tutorial on low power operation:

3
  • SSD1306 needs about 20mA.
  • Sounds reasonable, the Arduino can be put to sleep to save power.
    A MOSFET can control power to I/O when the Arduino is sleeping.
4

Can you explain what controlling the I/O with a mosfet means? Is this for the OLED?

5

  • When the Arduino goes to sleep, the Arduino current draw is very small.

  • While the Arduino is sleeping, I/O devices such as the OLED still draws power.
    We can turn off power to the OLED using a MOSFET, then turn OLED power back on when the Arduino wakes up.

6

I have a couple Pro Mini boards, one with 168A and the other with 328P chips. Will the low power mode work differently in each? Is one more efficient?

7

The "P" in ATmega328P means it has improved low power performance. All you need to know about that is presented in the tutorial linked in post #2.

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8

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