juckettd wrote: ↑Fri Feb 12, 2021 3:35 amI don't think you need step 2 in this situation. You can safely power down your device by doing the software shutdown and then pulling GLOBAL_EN low.
However, you actually don't even need to pull GLOBAL_EN low if you are also pulling power to the 5V rail through some other circuit. Pulling GLOBAL_EN is about disabling the other 3.3V and 1.8V rails that is providing power to other parts of the PI so that you can get it into the lowest possible power state. However, disconnecting the 5V power source is the same as pulling the power cord on the Raspberry PI 4B affer you run the shutdown command, which most people do when they are using their PI's.
So to summarize I would do the following:
1. If you won't be able to turn off the 5V power to the CM4, then run a software shutdown followed by pulling the GLOBAL_EN pin low to get the PI into the lowest possible power state
- or -
2. If you are able to turn off the 5V power to the CM4, then run a software shutdown followed by killing the 5V power on to the CM4
Hi, thanks for your reply and advice! Btw, you’re the person who made their own CM4 handheld right that was 3D printed? I’m a huge fan, it turned out great! Hopefully this one will be just as good as yours. Can I ask how you managed to do battery monitoring? Did you just use a basic ADC reading of battery voltage and then output that value after doing some manipulation with the discharge curves? I’ve been looking into the MAX17055 as there seems to be a Linux driver available for it, but I don’t really know how trivial it would be to get a HUD display working for that.
Pretty confident we can get a basic ADC module working for battery status (full, low, shutdown) etc but it won’t be nearly as accurate as a proper fuel gauge.
Cheers! Looking forward to seeing improvements of your model