blairfrandeen
commented
11 months ago Some measurements made with a DMM:
| Condition | Current Draw [mA] |
|---|---|
| Standby | 65.6 |
| Playing | 70-110 |
| Paused | 68.6 |
| RFID Chip present without magnet | 70.6 |
| Magnet present, no RFID | 69.5 |
| RFID, no magnet, after magnet had been activated | 74 |
| Crashed | 45 |
The 2X batteries I'm using have a capacity of 1500 mAh (3000 total). 3000 mAh / ~70 mA =~ 42 hours This operating time matches our experience with the momobox so far, although we typically get to about 24-30 hours before it turns off.
It may be promising to reduce power usage by rewriting the firmware in a lower level language that isn't constantly running an interpreter. For comparison, running "blinky" in Rust only takes 22-24 mA
The firmware runs continuously when the batteries are connected. Goal is to have the pico go into sleep mode after some amount of idle time, and then awake upon a signal from the hall sensor.
A good starting point with resources is here: https://ghubcoder.github.io/posts/deep-sleeping-the-pico-micropython/
May be better to also read this post about dormant and sleep modes: https://ghubcoder.github.io/posts/awaking-the-pico/
This is micropython based (momobox currently uses circuit python), so may not be fully applicable.
A good thing to start with is to measure the current draw from the batteries during the following operations: