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by pderocco
Thu Oct 04, 2018 1:31 am
Forum: Device Tree
Topic: Order of overlay loading during boot
Replies: 6
Views: 4861

Re: Order of overlay loading during boot

Sounds good. Thanks a lot for your help.
by pderocco
Tue Oct 02, 2018 10:06 pm
Forum: Device Tree
Topic: Order of overlay loading during boot
Replies: 6
Views: 4861

Re: Order of overlay loading during boot

Actually, I have a better way. I have a Kinetis K26 in my project already, for providing a USB device port. Since it boots up almost instantly, I can have it do any kind of power-down logic I want in firmware, including pulsing the GPIO 3 on the RPi CM3 at some more reasonable rate like 4Hz. Now tha...
by pderocco
Mon Oct 01, 2018 11:43 pm
Forum: Device Tree
Topic: Order of overlay loading during boot
Replies: 6
Views: 4861

Re: Order of overlay loading during boot

The gpio-poweroff driver is built into the kernel and loaded very early. The gpio-keys driver that implements gpio-shutdown is a module and loaded after the rootfs goes read/write. Making gpio-keys load earlier may be possible, but there has to be a system process running to detect the power-off ke...
by pderocco
Mon Oct 01, 2018 8:02 am
Forum: Device Tree
Topic: Order of overlay loading during boot
Replies: 6
Views: 4861

Re: Order of overlay loading during boot

One more question: 3) Is it guaranteed that when gpio-shutdown is initialized, there is an actual shutdown procedure that will shut things down? Or is there a short period when the GPIO has been configured to invoke some code enabled by the overlay, but it isn't actually able to do the shutdown? I'm...
by pderocco
Mon Oct 01, 2018 1:59 am
Forum: Device Tree
Topic: Order of overlay loading during boot
Replies: 6
Views: 4861

Order of overlay loading during boot

I have a tentative circuit for power switching the RPi CM3 that behaves like the power switching in a PC: 1) Pressing the button while the power is off turns it on; 2) Pressing the button again in the early stages of the boot turns it off; 3) Pressing the button once the system has enabled write acc...
by pderocco
Sun May 14, 2017 6:07 am
Forum: Compute Module
Topic: WiFi chip for Compute Module 3
Replies: 22
Views: 19242

WiFi chip for Compute Module 3

I'm thinking about using a CM3 in a project, but it needs WiFi. Apparently, the RPi 3B has a BCM43143 WiFi chip, but this doesn't appear to be readily available in modest quantities. And it is probably overkill, since I don't need an FM receiver, and I probably won't need Bluetooth. So what's the ea...
by pderocco
Sun May 14, 2017 5:40 am
Forum: General discussion
Topic: What is the highest quality touch screen available?
Replies: 1
Views: 633

Re: What is the highest quality touch screen available?

If this is a low volume project, you might look into replacement iPad screens, or perhaps Samsung tablet screens. The problem may be finding documentation on the connector pinout. I was considering a Samsung Note 3 or 4 phone screen for a smaller product, which you can easily buy, but I could never ...

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