At the top left of the reTerminal is a gray button with dimples. The documentation mentions this as a way to power it on of it has been shut down by software.
If I “sudo poweroff” on the reTerminal, it does not power back on from this button. When does it work?
Is there any way to access this button in code on a running reTerminal?
Thanks very much for any help
—Raymond
I think this is how it used to be thought… According to the “Raspberry Pi Compute Module 4 datasheet”.
Quote:
“2.13. Global_EN
Pulling this pin low puts the CM4 in the lowest possible power down state. After software shutdown Global_EN needs to be pulled low for > 1ms to restart the power system on the CM4.”
But according to “reTerminal Schematics v1.6” page 15, GLOBAL_EN would be pulled HIGH on key press if R268 is populated at all (is marked DNP, I think that means “do not populate”)
hxxps://datasheets.raspberrypi.com/cm4/cm4-datasheet.pdf
hxxps://files.seeedstudio.com/wiki/ReTerminal/reTerminal-v1.6_SCH.pdf
Thanks for your reply, but I’m having trouble extracting an answer to my question from it.
My take is that it’s mislabeled as a power on, and not adressable from software on a running Pi.
if the data sheet is correct, it will not work at all… I think… 
not without modifying the hardware…
but the button should pull LOW on GPIO13
datasheet page 15
but I am not quite sure what exactly Q20 is for
Great! Thanks very much
Followup - this button is recognized by the evtest utility
Event: time 1636034007.445084, type 1 (EV_KEY), code 142 (KEY_SLEEP), value 0
Event: time 1636034007.445084, -------------- SYN_REPORT ------------
I’ve been poking around a bit… Here are my guesses…
First of all, I’d like to note that it’s pretty uncool that neither components nor connectors are labeled. however, below left seems to be the unpopulated J3. Pin13 and 14 are RUN_PG_ON and GLOBAL_EN (page 5).to switch on, GLOBAL_EN should be pulled to the level of RUN_PG_ON via MOSFET Q20 (page 15). that seems to be the plan.
but RUN_PG_ON is not strong enough to pull down GOLBAL_EN, so GOBAL_EN (+5V) is instead pulled up RUN_PG_ON to 3,8V and GLOBAL_EN never reaches LOW level. …i guess…
Translated with DeepL 