DRAWS total failure Re: DRAWS audio crosstalk? #draws #direwolf
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Brian Badger
Well, I changed it back but now the entire draws overlay is broken -- totally broken top to bottom. No udrc audio device, no gps.
here is my entire /boot/config.txt hdmi_force_hotplug=1 hdmi_group=2 hdmi_mode=82 force_turbo=1 dtoverlay=draws #dtparam=audio=on
aplay: device_list:270: no soundcards found... pi@compass:~ $ ls /dev/ttySC0
ls: cannot access '/dev/ttySC0': No such file or directory pi@compass:~ $ ls /dev/pps0
ls: cannot access '/dev/pps0': No such file or directory
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Annaliese McDermond
You forgot the line
toggle quoted messageShow quoted text
dtoverlay= Before dtoverlay=draws You should have the following as the end of your file: dtoverlay= dtoverlay=draws dtparam=audio=on —Anna
On Dec 12, 2018, at 8:51 PM, Brian Badger <brian@...> wrote:
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Brian Badger
Thank you for the help. That resolved the issue.
Is there a configuration, installation, setup, or user guide document that you are referring to when you say "you forgot"? I assure you "forgot" isn't the problem. I can't forget something I don't know. I would love to know what else I don't know, but I can't find this stuff anywhere in the wiki. -- Brian N0KZ
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Annaliese McDermond
I’d have to demur to John on documentation as that’s more of his area. “Forgot” is probably a poor term. The only guide I’m referring to is my brain, but that’s because I’m the person who deals with drivers and systems integration. I could explain about the device tree and the raspberry pi, but not tapping it out at work on my phone :)
Much of this is standard raspian stuff. There is this thing called the device tree that describes the hardware to the Linux OS kernel. That’s what you’re playing with when you modify config.txt usually. That’s all documented by the Pi foundation. —Anna
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Brian Badger
Anna, Brian N0KZ
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I am not the expert, that would be Anna. My understanding is that dtoverlay= is basically clearing the device tree overlay list, then you can add overlays with subsequent dtoverlay parameters like dtoverlay=draws My guess is that the dtparam=audio=on comes after the draws information as it is adding an audio driver to the device tree. This is not an invention of NW Digital Radio, it is from standard Raspbian.
On Thu, Dec 13, 2018 at 3:06 PM Brian Badger <brian@...> wrote:
--
John D. Hays Edmonds, WA K7VE   
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Annaliese McDermond
On Dec 13, 2018, at 3:06 PM, Brian Badger <brian@badgerfamily.com> wrote:In the HAT spec, there’s room to put a chunk of device tree on a flash chip on the hardware itself. If the firmware sees this, it will load up that device tree overlay and merge it with the rest of the stuff it happens to be doing. With the UDRC we did this, although with changes to the kernel the HAT-embedded device tree became invalid. I’m working on a field programmer for that, but I only have a certain number of amateur time units with which to work on this kinda thing. What dtoverlay= does is clears out all device tree overlays whether they come from the HAT flash rom, or previous parameters in config.txt. We probably don’t really need it for the draws, but it’s absolutely necessary for udrc. Any dtoverlay/dtparam statements that come before this will essentially be ignored because dtoverlay= clears all of them out. So, you need to do the dtoverlay= first before you start loading other overlays or parameters. We would love to put the DRAWS overlay on the flash prom, but it slipped by us in testing that we’ve used a flash chip that’s too small to fit the overlay, hence you just have to use config.txt to load the overlay instead. Hopefully that answers some of your questions about how the firmware loads all the DT stuff. -- -- Annaliese McDermond (NH6Z) Xenotropic Systems mcdermj@xenotropic.com
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