Timeline for Control GPIO first thing on boot-up and last thing on shutdown
Current License: CC BY-SA 3.0
8 events
| when toggle format | what | by | license | comment | |
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| Oct 22, 2016 at 10:26 | comment | added | joan | @Jodes As far as I am aware, unless something actually uses the port (which is under your control) TXD will stay high between start-up and shutdown. | |
| Oct 22, 2016 at 9:08 | comment | added | Jayy | Ah I didn't read your answer properly - I just realised that a UART receiver in the circuit is not necessary - it just needs to monitor the level of the UART to pin and check that the pin stays low for the period of 10 bits or more, since the line stays high without data, and during data, the start/stop bits will guarantee the line will still periodically be high. | |
| Oct 19, 2016 at 20:46 | comment | added | joan |
I can't see that you can get an earlier start signal than the UART. I'm also not sure you can get a later stop signal. On the stop side perhaps look at /boot/overlays/README for gpio-poweroff.
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| Oct 19, 2016 at 20:39 | comment | added | Jayy | Very clever! Thanks! But if I wanted a simpler circuit, how early/late would regular output pins be settable? (And how might it be done?) | |
| Oct 19, 2016 at 20:37 | vote | accept | Jayy | ||
| Oct 19, 2016 at 20:19 | history | undeleted | joan | ||
| Oct 19, 2016 at 20:18 | history | deleted | joan | via Vote | |
| Oct 19, 2016 at 20:18 | history | answered | joan | CC BY-SA 3.0 |