The Raspberry Pi has been a revolutionary computer in the maker space, providing a full Linux environment, GUI, and tons of GPIO and other interfacing protocols at a considerably low price. This wasn’t its original intended goal, though. Back in the early 2010s it was supposed to be an educational tool for students first, not necessarily a go-to for every electronics project imaginable. As such there are a few issues with the platform when being used this way, and [Vin] addresses his problems with its power management in his latest project.
[Vin]’s main issue is that, unlike a microcontroller, the Raspberry Pi doesn’t have a deep sleep function. That means that even when the operating system is shut down the computer is still drawing an appreciable amount of current, which will quickly drain some batteries. We’ve covered [Vin]’s farm and his use case for the Raspberry Pi in the past, but a quick summary is that these boards are being used in a very rugged environment where utility power isn’t as reliable as he would like.
In [Vin]’s post he not only outlines his design for the board but goes through his design process, starting by using discrete logic components and then trying out various microcontrollers until settling on an ATmega88. The microcontroller communicates with the Raspberry Pi over I2C where the Pi can request a power-down as well as a time for future power-on. A latching relay controlled by the microcontroller ensures the Pi doesn’t drain any battery while the ATmega can put itself into actual sleep in the meantime.
The build for this project goes into an impressive amount of detail, and not only are the designs and code available on the project’s GitHub page but [Vin] also wrote another blog post which uses this project to go over his design philosophy more broadly.
There’s a few projects like this that add a real ‘power off’ with timer / wake-on-xxx events. They are obviously fairly useful for certain use cases like intermittent monitoring. But they are far from ‘comprehensive.’ There’s a whole spectrum of power management features for other platforms. The ‘off’ setting is only one of them.
Why does the pi draw so much power when “shut down”?
I’ve been down this (power management) road before and arrived at Attiny13 instead.
Modern equivalent will be Attiny85/88, excellent upgrade to Attiny13, but as usual, if it can be done with Arduino, it can be done with 555s :- ] I just happened to find my personal equivalent of 555s : -]
Check out CH32V003 – super cheap, 32bit, i really like it. Fairly easy to use.
For any application the ch32v003 would be better than a 555 for timer stuff just because of how meh the standard 555 is.
But for low power the ATtiny13A is better as you can run it at a 1/4 the minimum clock rate compared to the ch32v003.
Also at a lower voltage and current.
DIP better than TSOP, 555 forever :)